EVS UMN UPDATE

Reviewed-by: Muller, Martin <martin.muller@t-systems.com>
Co-authored-by: Zaoxu, Li <lizaoxu@huawei.com>
Co-committed-by: Zaoxu, Li <lizaoxu@huawei.com>

docs/evs/umn/en-us_topic_0032860759.html

@@ -1,36 +1,36 @@
 <a name="en-us_topic_0032860759"></a><a name="en-us_topic_0032860759"></a>
 
-<h1 class="topictitle1">Shared EVS Disks and Usage Instructions</h1>
-<div id="body1506325324297"><div class="section" id="en-us_topic_0032860759__section14853146154645"><h4 class="sectiontitle">What Are Shared EVS Disks?</h4><p id="en-us_topic_0032860759__p23931035154645">Shared EVS disks are block storage devices that support concurrent read/write operations and can be attached to multiple <span id="en-us_topic_0032860759__text1202456375165636">servers</span>. Shared EVS disks feature multiple attachments, high-concurrency, high-performance, and high-reliability. They are usually used for enterprise business-critical applications that require cluster deployment and high availability (HA). Multiple <span id="en-us_topic_0032860759__text4727122119232">servers</span> can access the same shared EVS disk at the same time.</p>
-<p id="en-us_topic_0032860759__p34083125112">A shared EVS disk can be attached to a maximum of 16 <span id="en-us_topic_0032860759__text18175184004110">servers</span>. Servers that EVS supports include ECSs and BMSs. To share files, you need to deploy a shared file system or a cluster management system, such as Windows MSCS, Veritas VCS, or CFS.</p>
-<div class="notice" id="en-us_topic_0032860759__note1821913121217"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="en-us_topic_0032860759__p12821713141210">You must set up a shared file system or cluster management system before using shared EVS disks. If you directly attach a disk to multiple <span id="en-us_topic_0032860759__text1888310409388">server</span>s, the sharing function will not work and data may be overwritten.</p>
+<h1 class="topictitle1">Disk Sharing</h1>
+<div id="body8662426"><div class="section" id="en-us_topic_0032860759__en-us_topic_0078247522_section14853146154645"><h4 class="sectiontitle">What Is Disk Sharing?</h4><p id="en-us_topic_0032860759__en-us_topic_0078247522_p23931035154645">Disk sharing allows you to create shared EVS disks. Shared EVS disks are block storage devices that support concurrent read/write operations and can be attached to multiple <span id="en-us_topic_0032860759__text1202456375165636">servers</span>. Shared EVS disks provide multiple attachments, high concurrency, high performance, and high reliability. They are usually used for enterprise business-critical applications that require cluster deployment and high availability (HA). Multiple <span id="en-us_topic_0032860759__en-us_topic_0078247522_text4727122119232">servers</span> can access the same shared EVS disk at the same time.</p>
+<p id="en-us_topic_0032860759__en-us_topic_0078247522_p34083125112">A shared EVS disk can be attached to a maximum of 16 <span id="en-us_topic_0032860759__en-us_topic_0078247522_text18175184004110">servers</span>, including ECSs or BMSs. To share files, you need to deploy a shared file system or a cluster management system, such as Windows MSCS, Veritas VCS, or CFS.</p>
+<div class="notice" id="en-us_topic_0032860759__en-us_topic_0078247522_note1821913121217"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="en-us_topic_0032860759__en-us_topic_0078247522_p12821713141210">A shared file system or cluster management system must be set up before you can properly use a shared disk. If you simply attach a shared disk to multiple <span id="en-us_topic_0032860759__text3635181521716">server</span>s, data cannot be shared between those servers and may be overwritten.</p>
 </div></div>
 </div>
-<div class="fignone" id="en-us_topic_0032860759__fig186617301262"><span class="figcap"><b>Figure 1 </b>Application scenario of shared EVS disks</span><br><span><img id="en-us_topic_0032860759__image086623019618" src="en-us_image_0197136031.png"></span></div>
-<div class="section" id="en-us_topic_0032860759__section20091124154758"><h4 class="sectiontitle">Usage Precautions</h4><p id="en-us_topic_0032860759__p680541418427">Because most cluster applications, such as Windows MSCS, Veritas VCS, and Veritas CFS, require SCSI reservations, you are advised to use shared EVS disks with SCSI. If a SCSI EVS disk is attached to a Xen ECS, you must install the driver. For details, see <a href="en-us_topic_0052554220.html">Device Types and Usage Instructions</a>.</p>
-<div class="p" id="en-us_topic_0032860759__p133731412155317">You can create shared VBD disks or shared SCSI disks. It is recommended that you attach a shared disk to the ECSs in the same ECS group to improve service reliability.<ul id="en-us_topic_0032860759__evs_01_0010_ul290254221927"><li id="en-us_topic_0032860759__evs_01_0010_li54944535221927">Shared VBD disks: The device type of a newly created shared disk is VBD by default. Such disks can be used as virtual block storage devices, but do not support SCSI reservations. If SCSI reservations are required for your applications, create shared SCSI EVS disks.</li><li id="en-us_topic_0032860759__evs_01_0010_li59684574221927">Shared SCSI disks: Such disks support SCSI reservations.<div class="notice" id="en-us_topic_0032860759__evs_01_0010_note57683778221927"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="en-us_topic_0032860759__evs_01_0010_ul8479164912431"><li id="en-us_topic_0032860759__evs_01_0010_li34792499432">To improve data security, you are advised to use SCSI reservations together with the anti-affinity policy of an ECS group. That said, ensure that shared SCSI disks are only attached to ECSs in the same anti-affinity ECS group.</li><li id="en-us_topic_0032860759__evs_01_0010_li67215539435">If an ECS does not belong to any anti-affinity ECS group, you are advised not to attach shared SCSI disks to this ECS. Otherwise, SCSI reservations may not work properly, which may put your data at risk.</li></ul>
+<div class="fignone" id="en-us_topic_0032860759__en-us_topic_0078247522_fig186617301262"><span class="figcap"><b>Figure 1 </b>Application scenario of shared EVS disks</span><br><span><img id="en-us_topic_0032860759__en-us_topic_0078247522_image086623019618" src="en-us_image_0000002049223182.png"></span></div>
+<div class="section" id="en-us_topic_0032860759__en-us_topic_0078247522_section20091124154758"><h4 class="sectiontitle">Important Notes on Using Shared EVS Disks</h4><p id="en-us_topic_0032860759__en-us_topic_0078247522_p680541418427">Because most cluster applications, such as Windows MSCS, Veritas VCS, and Veritas CFS, require SCSI reservations, you are advised to use shared EVS disks with SCSI. If a SCSI EVS disk is attached to a Xen ECS, you must install the driver. For details, see <a href="en-us_topic_0052554220.html">Device Types</a>.</p>
+<div class="p" id="en-us_topic_0032860759__en-us_topic_0078247522_p133731412155317">You can create shared VBD disks or shared SCSI disks. It is recommended that you attach a shared disk to ECSs in the same ECS group to improve service reliability.<ul id="en-us_topic_0032860759__en-us_topic_0077504313_ul290254221927"><li id="en-us_topic_0032860759__en-us_topic_0077504313_li54944535221927">Shared VBD disks: The device type of a newly created shared disk is VBD by default. Such disks can be used as virtual block storage devices, but do not support SCSI reservations. If SCSI reservations are required for your applications, create shared SCSI EVS disks.</li><li id="en-us_topic_0032860759__en-us_topic_0077504313_li59684574221927">Shared SCSI disks: Such disks support SCSI reservations.<div class="notice" id="en-us_topic_0032860759__en-us_topic_0077504313_note57683778221927"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="en-us_topic_0032860759__en-us_topic_0077504313_ul8479164912431"><li id="en-us_topic_0032860759__en-us_topic_0077504313_li34792499432">To improve data security, you are advised to use SCSI reservations together with the anti-affinity policy of an ECS group. That said, ensure that shared SCSI disks are only attached to ECSs in the same anti-affinity ECS group.</li><li id="en-us_topic_0032860759__en-us_topic_0077504313_li67215539435">If an ECS does not belong to any anti-affinity ECS group, you are advised not to attach shared SCSI disks to this ECS. Otherwise, SCSI reservations may not work properly, which may put your data at risk.</li></ul>
 </div></div>
-<p id="en-us_topic_0032860759__evs_01_0010_p25421542202933">Concepts of the anti-affinity ECS group and SCSI reservations:</p>
-<ul id="en-us_topic_0032860759__evs_01_0010_ul25591981221927"><li id="en-us_topic_0032860759__evs_01_0010_li61712662221927">The anti-affinity policy of an ECS group allows ECSs to be created on different physical servers to improve service reliability.<p id="en-us_topic_0032860759__evs_01_0010_p10472930123111"><a name="en-us_topic_0032860759__evs_01_0010_li61712662221927"></a><a name="evs_01_0010_li61712662221927"></a>For details about ECS groups, see <span class="wintitle" id="en-us_topic_0032860759__evs_01_0010_wintitle38764784314438"><b>Managing ECS Groups</b></span> in the <em id="en-us_topic_0032860759__evs_01_0010_i842352697144323">Elastic Cloud Server User Guide</em>.</p>
-</li><li id="en-us_topic_0032860759__evs_01_0010_li18543049221927">The SCSI reservation mechanism uses a SCSI reservation command to perform SCSI reservation operations. If an ECS sends such a command to an EVS disk, the disk is displayed as locked to other ECSs, preventing the data damage that may be caused by simultaneous read/write operations to the disk from multiple ECSs.</li><li id="en-us_topic_0032860759__evs_01_0010_li32669715221927">ECS groups and SCSI reservations have the following relationship: A SCSI reservation on a single EVS disk cannot differentiate multiple ECSs on the same physical host. For that reason, if multiple ECSs that use the same shared EVS disk are running on the same physical host, SCSI reservations will not work properly. So you are advised to use SCSI reservations only on ECSs that are in the same ECS group, thus having a working anti-affinity policy. </li></ul>
+<p id="en-us_topic_0032860759__en-us_topic_0077504313_p25421542202933">Concepts of the anti-affinity ECS group and SCSI reservations:</p>
+<ul id="en-us_topic_0032860759__en-us_topic_0077504313_ul25591981221927"><li id="en-us_topic_0032860759__en-us_topic_0077504313_li61712662221927">The anti-affinity policy of an ECS group allows ECSs to be created on different physical servers to improve service reliability.<p id="en-us_topic_0032860759__en-us_topic_0077504313_p10472930123111"><a name="en-us_topic_0032860759__en-us_topic_0077504313_li61712662221927"></a><a name="en-us_topic_0077504313_li61712662221927"></a>For details about ECS groups, see <span class="wintitle" id="en-us_topic_0032860759__en-us_topic_0077504313_wintitle38764784314438"><b>Managing ECS Groups</b></span> in the <em id="en-us_topic_0032860759__en-us_topic_0077504313_i842352697144323">Elastic Cloud Server User Guide</em>.</p>
+</li><li id="en-us_topic_0032860759__en-us_topic_0077504313_li18543049221927">The SCSI reservation mechanism uses a SCSI reservation command to perform SCSI reservation operations. If an ECS sends such a command to an EVS disk, the disk is displayed as locked to other ECSs, preventing the data damage that may be caused by simultaneous reads/writes to the disk from multiple ECSs.</li><li id="en-us_topic_0032860759__en-us_topic_0077504313_li32669715221927">ECS groups and SCSI reservations have the following relationship: A SCSI reservation on a single EVS disk cannot differentiate multiple ECSs on the same physical host. For that reason, if multiple ECSs that use the same shared EVS disk are running on the same physical host, SCSI reservations will not work properly. So you are advised to use SCSI reservations only on ECSs that are in the same ECS group, thus having a working anti-affinity policy. </li></ul>
 </li></ul>
 </div>
 </div>
-<div class="section" id="en-us_topic_0032860759__section14238006154818"><h4 class="sectiontitle">Advantages</h4><ul id="en-us_topic_0032860759__ul9580578154818"><li id="en-us_topic_0032860759__li17861603154818">Multiple attachments: A shared EVS disk can be attached to a maximum of 16 <span id="en-us_topic_0032860759__text1908525931165848">servers</span>.</li><li id="en-us_topic_0032860759__li37750119154818">High-performance: The random read/write IOPS of a shared ultra-high I/O disk can reach up to 160,000.</li><li id="en-us_topic_0032860759__li21255070154818">High-reliability: Shared EVS disks support both manual and automatic backup, delivering highly reliable data storage.</li><li id="en-us_topic_0032860759__li62322105154818">Wide range of use: Shared EVS disks can be used for Linux RHCS clusters where only VBD EVS disks are needed. They can also be used for Windows MSCS and Veritas VCS clusters that require SCSI reservations.</li></ul>
+<div class="section" id="en-us_topic_0032860759__en-us_topic_0078247522_section14238006154818"><h4 class="sectiontitle">Advantages</h4><ul id="en-us_topic_0032860759__en-us_topic_0078247522_ul9580578154818"><li id="en-us_topic_0032860759__en-us_topic_0078247522_li17861603154818">Multiple attachments: A shared EVS disk can be attached to a maximum of 16 <span id="en-us_topic_0032860759__text1908525931165848">servers</span>.</li><li id="en-us_topic_0032860759__en-us_topic_0078247522_li37750119154818">High-performance: The random read/write IOPS of a shared ultra-high I/O disk can reach up to 160,000.</li><li id="en-us_topic_0032860759__en-us_topic_0078247522_li21255070154818">High-reliability: Shared EVS disks support both manual and automatic backup, delivering highly reliable data storage.</li><li id="en-us_topic_0032860759__en-us_topic_0078247522_li62322105154818">Wide range of use: Shared EVS disks can be used for Linux RHCS clusters where only shared VBD disks are needed. They can also be used for Windows MSCS and Veritas VCS clusters that require SCSI reservations.</li></ul>
 </div>
-<div class="section" id="en-us_topic_0032860759__section2163128202216"><h4 class="sectiontitle">Specifications and Performance</h4><p id="en-us_topic_0032860759__p1779261542215">Shared EVS disks have the same specifications and performance as non-shared EVS disks.</p>
+<div class="section" id="en-us_topic_0032860759__en-us_topic_0078247522_section2163128202216"><h4 class="sectiontitle">Specifications and Performance</h4><p id="en-us_topic_0032860759__en-us_topic_0078247522_p1779261542215">Shared EVS disks have the same specifications and performance as non-shared EVS disks.</p>
 </div>
-<div class="section" id="en-us_topic_0032860759__section23510620221927"><h4 class="sectiontitle">Data Sharing Principle and Common Usage Mistakes</h4><p id="en-us_topic_0032860759__p3186456916184">A shared EVS disk is essentially the disk that can be attached to multiple <span id="en-us_topic_0032860759__text176062173819384">servers</span> for use, which is similar to a physical disk in that the disk can be attached to multiple physical servers, and each server can read data from and write data into any space on the disk. If the data read/write rules, such as the read/write sequence and meaning, between these servers are not defined, data read/write interference between servers or other unpredictable errors may occur.</p>
-<p id="en-us_topic_0032860759__p885410333452">Though shared EVS disks are block storage devices that provide shared access for <span id="en-us_topic_0032860759__text1369390954191359">servers</span>, shared EVS disks do not have the cluster management capability. Therefore, you need to deploy a cluster system to manage shared EVS disks. Common cluster management systems include Windows MSCS, Linux RHCS, Veritas VCS, and Veritas CFS.</p>
-<div class="p" id="en-us_topic_0032860759__p51411880161521">If shared EVS disks are not managed by a cluster system, the following issues may occur:<ul id="en-us_topic_0032860759__ul12861420163611"><li id="en-us_topic_0032860759__li66334774163611">Data inconsistency caused by read/write conflicts<p id="en-us_topic_0032860759__p1449952152546"><a name="en-us_topic_0032860759__li66334774163611"></a><a name="li66334774163611"></a>When a shared EVS disk is attached to two <span id="en-us_topic_0032860759__text1431929819172447">servers</span> (<span id="en-us_topic_0032860759__text833991954172538">server</span> A and <span id="en-us_topic_0032860759__text1227918281172538">server</span> B), <span id="en-us_topic_0032860759__text127370268717265">server</span> A cannot recognize the disk spaces allocated to <span id="en-us_topic_0032860759__text1577214107173018">server</span> B, vice versa. That said, a disk space allocated to <span id="en-us_topic_0032860759__text3224160517311">server</span> A may be already used by <span id="en-us_topic_0032860759__text1531578381173151">server</span> B. In this case, repeated disk space allocation occurs, which leads to data errors.</p>
-<p id="en-us_topic_0032860759__p4915808612232">For example, a shared EVS disk has been formatted into the ext3 file system and attached to <span id="en-us_topic_0032860759__text1760168219173916">server</span> A and <span id="en-us_topic_0032860759__text1394632296173916">server</span> B. Server A has written metadata into the file system in space R and space G. Then <span id="en-us_topic_0032860759__text136414404174339">server</span> B has written metadata into space E and space G. In this case, the data written into space G by <span id="en-us_topic_0032860759__text363828490174658">server</span> A will be replaced. When the metadata in space G is read, an error will occur.</p>
-</li><li id="en-us_topic_0032860759__li3634842616506">Data inconsistency caused by data caching<p id="en-us_topic_0032860759__p62996035164415"><a name="en-us_topic_0032860759__li3634842616506"></a><a name="li3634842616506"></a>When a shared EVS disk is attached to two <span id="en-us_topic_0032860759__text862876140185720">servers</span> (<span id="en-us_topic_0032860759__text797923257185720">server</span> A and <span id="en-us_topic_0032860759__text652386341185720">server</span> B), the application on <span id="en-us_topic_0032860759__text116818292185837">server</span> A has read the data in space R and space G, then cached the data. At that time, other processes and threads on <span id="en-us_topic_0032860759__text206936123819142">server</span> A would then read this data directly from the cache. At the same time, if the application on <span id="en-us_topic_0032860759__text2290166181935">server</span> B has modified the data in space R and space G, the application on <span id="en-us_topic_0032860759__text181129823019428">server</span> A cannot detect this data change and still reads this data from the cache. As a result, the user cannot view the modified data on <span id="en-us_topic_0032860759__text10758688219823">server</span> A.</p>
-<p id="en-us_topic_0032860759__p64639998152256">For example, a shared EVS disk has been formatted into the ext3 file system and attached to <span id="en-us_topic_0032860759__text8378937071994">server</span> A and <span id="en-us_topic_0032860759__text7722401061994">server</span> B. Both <span id="en-us_topic_0032860759__text149132857619924">servers</span> have cached the metadata in the file system. Then <span id="en-us_topic_0032860759__text92088787319952">server</span> A has created a new file (file F) on the shared disk, but <span id="en-us_topic_0032860759__text646572161191039">server</span> B cannot detect this modification and still reads data from its cached data. As a result, the user cannot view file F on <span id="en-us_topic_0032860759__text4066463219110">server</span> B.</p>
+<div class="section" id="en-us_topic_0032860759__en-us_topic_0078247522_section23510620221927"><h4 class="sectiontitle">Data Sharing Principles and Common Usage Mistakes</h4><p id="en-us_topic_0032860759__en-us_topic_0078247522_p3186456916184">A shared EVS disk is essentially the disk that can be attached to multiple <span id="en-us_topic_0032860759__text176062173819384">servers</span> for use. It is similar to a physical disk in that the disk can be attached to multiple physical servers, and each server can read data from and write data to any space on the disk. If no data read/write rules, such as the read/write sequence and meaning, between these servers are defined, data reads and writes between these servers may conflict, or other unpredictable errors may occur.</p>
+<p id="en-us_topic_0032860759__en-us_topic_0078247522_p885410333452">Though shared EVS disks are block storage devices that provide shared access for <span id="en-us_topic_0032860759__text1369390954191359">servers</span>, shared EVS disks do not have the cluster management capability. You need to deploy a cluster system to manage shared EVS disks. Common cluster management systems include Windows MSCS, Linux RHCS, Veritas VCS, and Veritas CFS.</p>
+<div class="p" id="en-us_topic_0032860759__en-us_topic_0078247522_p51411880161521">If shared EVS disks are not managed by a cluster system, the following issues may occur:<ul id="en-us_topic_0032860759__en-us_topic_0078247522_ul12861420163611"><li id="en-us_topic_0032860759__en-us_topic_0078247522_li66334774163611">Data inconsistency caused by read/write conflicts<p id="en-us_topic_0032860759__en-us_topic_0078247522_p1449952152546"><a name="en-us_topic_0032860759__en-us_topic_0078247522_li66334774163611"></a><a name="en-us_topic_0078247522_li66334774163611"></a>When a shared EVS disk is attached to two <span id="en-us_topic_0032860759__text1431929819172447">servers</span> (<span id="en-us_topic_0032860759__text833991954172538">server</span> A and <span id="en-us_topic_0032860759__text1227918281172538">server</span> B), <span id="en-us_topic_0032860759__text127370268717265">server</span> A cannot recognize the disk spaces allocated to <span id="en-us_topic_0032860759__text1577214107173018">server</span> B, vice versa. That said, a disk space allocated to <span id="en-us_topic_0032860759__text3224160517311">server</span> A may be already used by <span id="en-us_topic_0032860759__text1531578381173151">server</span> B. In this case, repeated disk space allocation occurs, which leads to data errors.</p>
+<p id="en-us_topic_0032860759__en-us_topic_0078247522_p4915808612232">For example, a shared EVS disk has been formatted into an ext3 file system and attached to <span id="en-us_topic_0032860759__text1760168219173916">server</span> A and <span id="en-us_topic_0032860759__text1394632296173916">server</span> B. Server A has written metadata into the file system in space R and space G. Then <span id="en-us_topic_0032860759__text136414404174339">server</span> B has written metadata into space E and space G. In this case, the data written into space G by <span id="en-us_topic_0032860759__text363828490174658">server</span> A will be replaced. When the metadata in space G is read, an error will occur.</p>
+</li><li id="en-us_topic_0032860759__en-us_topic_0078247522_li3634842616506">Data inconsistency caused by data caching<p id="en-us_topic_0032860759__en-us_topic_0078247522_p62996035164415"><a name="en-us_topic_0032860759__en-us_topic_0078247522_li3634842616506"></a><a name="en-us_topic_0078247522_li3634842616506"></a>When a shared EVS disk is attached to two <span id="en-us_topic_0032860759__text862876140185720">servers</span> (<span id="en-us_topic_0032860759__text797923257185720">server</span> A and <span id="en-us_topic_0032860759__text652386341185720">server</span> B), the application on <span id="en-us_topic_0032860759__text116818292185837">server</span> A has read the data in space R and space G, then cached the data. At that time, other processes and threads on <span id="en-us_topic_0032860759__text206936123819142">server</span> A would then read this data directly from the cache. At the same time, if the application on <span id="en-us_topic_0032860759__text2290166181935">server</span> B has modified the data in space R and space G, the application on <span id="en-us_topic_0032860759__text181129823019428">server</span> A cannot detect this data change and still reads this data from the cache. As a result, the modified data cannot be viewed on <span id="en-us_topic_0032860759__text10758688219823">server</span> A.</p>
+<p id="en-us_topic_0032860759__en-us_topic_0078247522_p64639998152256">For example, a shared EVS disk has been formatted into an ext3 file system and attached to <span id="en-us_topic_0032860759__text8378937071994">server</span> A and <span id="en-us_topic_0032860759__text7722401061994">server</span> B. Both <span id="en-us_topic_0032860759__text149132857619924">servers</span> have cached the metadata in the file system. Then <span id="en-us_topic_0032860759__text92088787319952">server</span> A has created a new file (file F) on the shared disk, but <span id="en-us_topic_0032860759__text646572161191039">server</span> B cannot detect this modification and still reads data from its cached data. As a result, file F cannot be viewed on <span id="en-us_topic_0032860759__text4066463219110">server</span> B.</p>
 </li></ul>
 </div>
-<p id="en-us_topic_0032860759__p53108593165417">Before you attach a shared EVS disk to multiple <span id="en-us_topic_0032860759__text183449198819124">servers</span>, the disk device type needs to be determined. The device type can be either VBD or SCSI. Shared SCSI EVS disks support SCSI reservations. Before using SCSI reservations, you need to install a driver in <span id="en-us_topic_0032860759__text885114752191336">the server</span> OS and ensure that the OS image is included in the compatibility list.</p>
-<p id="en-us_topic_0032860759__p48653461174019">For details about the usages of shared EVS disks, see <a href="evs_01_0010.html">Managing Shared EVS Disks</a>.</p>
-<div class="notice" id="en-us_topic_0032860759__note60886722162923"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="en-us_topic_0032860759__p11109594162923">If you simply attach a shared EVS disk to multiple <span id="en-us_topic_0032860759__text1879706293191451">servers</span>, files cannot be shared between the <span id="en-us_topic_0032860759__text1342408225191536">servers</span> as shared EVS disks do not have the cluster capability. Therefore, build a shared file system or deploy a cluster management system if you need to share files between <span id="en-us_topic_0032860759__text1454148709191822">servers</span>.</p>
+<p id="en-us_topic_0032860759__en-us_topic_0078247522_p53108593165417">Before you buy a shared EVS disk, determine its device type (VBD or SCSI) based on the applications that will use the shared disk. Shared SCSI EVS disks support SCSI reservations. Before using SCSI reservations, you need to install a driver in <span id="en-us_topic_0032860759__text885114752191336">the server</span> OS and ensure that the OS image is included in the compatibility list.</p>
+<p id="en-us_topic_0032860759__en-us_topic_0078247522_p48653461174019">For details about how to use shared EVS disks, see <a href="evs_01_0010.html">Managing Shared EVS Disks</a>.</p>
+<div class="notice" id="en-us_topic_0032860759__en-us_topic_0078247522_note60886722162923"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="en-us_topic_0032860759__en-us_topic_0078247522_p11109594162923">If you simply attach a shared disk to multiple <span id="en-us_topic_0032860759__text973812851920">servers</span>, data or files cannot be shared between the servers, because the shared disk does not have the cluster management capability. To share files between <span id="en-us_topic_0032860759__text1273817851918">servers</span>, build a shared file system or deploy a cluster management system.</p>
 </div></div>
 </div>
 </div>

docs/evs/umn/en-us_topic_0052554220.html

@@ -1,43 +1,43 @@
 <a name="en-us_topic_0052554220"></a><a name="en-us_topic_0052554220"></a>
 
-<h1 class="topictitle1">Device Types and Usage Instructions</h1>
-<div id="body1506325324297"><div class="section" id="en-us_topic_0052554220__section4216899312115"><h4 class="sectiontitle">What Device Types Are Available?</h4><div class="p" id="en-us_topic_0052554220__p61039812154429">There are two EVS device types: Virtual Block Device (VBD) and Small Computer System Interface (SCSI).<ul id="en-us_topic_0052554220__ul30912861154429"><li id="en-us_topic_0052554220__li28903436154429">VBD is the default EVS device type. VBD EVS disks support only basic read/write SCSI commands.</li><li id="en-us_topic_0052554220__li19624421154429">SCSI EVS disks support transparent SCSI command transmission and allow the <span id="en-us_topic_0052554220__text63384940152857">server</span> OS to directly access the underlying storage media. Besides basic read/write SCSI commands, SCSI disks support advanced SCSI commands.</li></ul>
+<h1 class="topictitle1">Device Types</h1>
+<div id="body8662426"><div class="section" id="en-us_topic_0052554220__en-us_topic_0078247521_section4216899312115"><h4 class="sectiontitle">What Device Types Are Available?</h4><div class="p" id="en-us_topic_0052554220__en-us_topic_0078247521_p61039812154429">There are two EVS device types: Virtual Block Device (VBD) and Small Computer System Interface (SCSI).<ul id="en-us_topic_0052554220__en-us_topic_0078247521_ul30912861154429"><li id="en-us_topic_0052554220__en-us_topic_0078247521_li28903436154429">VBD is the default EVS device type. VBD EVS disks support only basic read/write SCSI commands.</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li19624421154429">SCSI EVS disks support transparent SCSI command transmission and allow the <span id="en-us_topic_0052554220__en-us_topic_0078247521_text63384940152857">server</span> OS to directly access the underlying storage media. Besides basic read/write SCSI commands, SCSI disks support advanced SCSI commands.</li></ul>
 </div>
-<p id="en-us_topic_0052554220__p1669516467462">Device type is configured during creation. It cannot be changed after the disk has been created.</p>
+<p id="en-us_topic_0052554220__en-us_topic_0078247521_p1669516467462">Device type is configured during creation. It cannot be changed after the disk has been created.</p>
 </div>
-<div class="section" id="en-us_topic_0052554220__section5554506411"><h4 class="sectiontitle">Common Application Scenarios and Usage Instructions of SCSI EVS Disks</h4><ul id="en-us_topic_0052554220__ul649313366412"><li id="en-us_topic_0052554220__li16493193619415">BMSs support only SCSI EVS disks.</li><li id="en-us_topic_0052554220__li72111959105511">Shared SCSI EVS disks: Shared SCSI EVS disks must be used together with a distributed file system or cluster software. Because most cluster applications, such as Windows MSCS, Veritas VCS, and Veritas CFS, require SCSI reservations, you are advised to use shared EVS disks with SCSI.<p id="en-us_topic_0052554220__p2086018215561"><a name="en-us_topic_0052554220__li72111959105511"></a><a name="li72111959105511"></a>SCSI reservations take effect only when shared SCSI EVS disks are attached to ECSs in the same ECS group. For more information about shared EVS disks, see <a href="en-us_topic_0032860759.html">Shared EVS Disks and Usage Instructions</a>.</p>
+<div class="section" id="en-us_topic_0052554220__en-us_topic_0078247521_section5554506411"><h4 class="sectiontitle">Common Application Scenarios and Usage Instructions of SCSI EVS Disks</h4><ul id="en-us_topic_0052554220__en-us_topic_0078247521_ul649313366412"><li id="en-us_topic_0052554220__en-us_topic_0078247521_li16493193619415">BMSs support only SCSI EVS disks.</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li72111959105511">Shared SCSI EVS disks: Shared SCSI EVS disks must be used together with a distributed file system or cluster software. Because most cluster applications, such as Windows MSCS, Veritas VCS, and Veritas CFS, require SCSI reservations, you are advised to use shared EVS disks with SCSI.<p id="en-us_topic_0052554220__en-us_topic_0078247521_p2086018215561"><a name="en-us_topic_0052554220__en-us_topic_0078247521_li72111959105511"></a><a name="en-us_topic_0078247521_li72111959105511"></a>SCSI reservations take effect only when shared SCSI EVS disks are attached to ECSs in the same ECS group.</p>
 </li></ul>
 </div>
-<div class="section" id="en-us_topic_0052554220__section1071245115370"><h4 class="sectiontitle">Do I Need to Install a Driver for SCSI EVS Disks?</h4><p id="en-us_topic_0052554220__p188631912362">To use SCSI EVS disks, a cloud server must have a SCSI driver installed. If the SCSI driver is not pre-installed, you need to install it manually.</p>
-<div class="p" id="en-us_topic_0052554220__p07141451113718">Check whether you need to manually install the driver based on the server type.<ul id="en-us_topic_0052554220__ul16715115193714"><li id="en-us_topic_0052554220__li1071685113714">Bare Metal Server (BMS)<p id="en-us_topic_0052554220__p5219775328"><a name="en-us_topic_0052554220__li1071685113714"></a><a name="li1071685113714"></a>Both the Windows and Linux images for BMSs are pre-installed with the required SDI card driver. Therefore, no driver needs to be installed.</p>
-</li><li id="en-us_topic_0052554220__li171965111371">KVM ECS<p id="en-us_topic_0052554220__p3966175719482"><a name="en-us_topic_0052554220__li171965111371"></a><a name="li171965111371"></a>You are advised to use SCSI EVS disks with KVM ECSs. Linux images and Windows images for KVM ECSs already have the required driver. Therefore, no driver needs to be installed for KVM ECSs.</p>
-<div class="note" id="en-us_topic_0052554220__note159311959182312"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="en-us_topic_0052554220__p1165651172712">ECS virtualization types are categorized into KVM and Xen. For details, see <a href="https://docs.otc.t-systems.com/en-us/usermanual/ecs/en-us_topic_0035470096.html" target="_blank" rel="noopener noreferrer">ECS Types</a>.</p>
+<div class="section" id="en-us_topic_0052554220__en-us_topic_0078247521_section1071245115370"><h4 class="sectiontitle">Do I Need to Install a Driver for SCSI EVS Disks?</h4><p id="en-us_topic_0052554220__en-us_topic_0078247521_p188631912362">To use SCSI EVS disks, a cloud server must have a SCSI driver installed. If the SCSI driver is not pre-installed, you need to install it manually.</p>
+<div class="p" id="en-us_topic_0052554220__en-us_topic_0078247521_p07141451113718">Check whether you need to manually install the driver based on the server type.<ul id="en-us_topic_0052554220__en-us_topic_0078247521_ul16715115193714"><li id="en-us_topic_0052554220__en-us_topic_0078247521_li1071685113714">Bare Metal Server (BMS)<p id="en-us_topic_0052554220__en-us_topic_0078247521_p5219775328"><a name="en-us_topic_0052554220__en-us_topic_0078247521_li1071685113714"></a><a name="en-us_topic_0078247521_li1071685113714"></a>Both the Windows and Linux images for BMSs are pre-installed with the required SDI card driver. Therefore, no driver needs to be installed.</p>
+</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li171965111371">KVM ECS<p id="en-us_topic_0052554220__en-us_topic_0078247521_p3966175719482"><a name="en-us_topic_0052554220__en-us_topic_0078247521_li171965111371"></a><a name="en-us_topic_0078247521_li171965111371"></a>You are advised to use SCSI EVS disks with KVM ECSs. Linux images and Windows images for KVM ECSs already have the required driver. Therefore, no driver needs to be installed for KVM ECSs.</p>
+<div class="note" id="en-us_topic_0052554220__en-us_topic_0078247521_note159311959182312"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="en-us_topic_0052554220__en-us_topic_0078247521_p1165651172712">ECS virtualization types are categorized into KVM and Xen. For details, see <a href="https://docs.otc.t-systems.com/en-us/usermanual/ecs/en-us_topic_0035470096.html" target="_blank" rel="noopener noreferrer">ECS Types</a>.</p>
 </div></div>
-</li><li id="en-us_topic_0052554220__li150525682717">Xen ECS<p id="en-us_topic_0052554220__p187715594275"><a name="en-us_topic_0052554220__li150525682717"></a><a name="li150525682717"></a>Due to driver limitations, you are advised not to use SCSI EVS disk with Xen ECSs.</p>
-<div class="p" id="en-us_topic_0052554220__p1138811165919">However, a few images support SCSI EVS disks on Xen ECSs. For the supported images, see <a href="#en-us_topic_0052554220__table36381951181116">Table 1</a>.<div class="note" id="en-us_topic_0052554220__note225774621212"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="en-us_topic_0052554220__p343064525713">After confirming that the OS images of Xen ECSs support SCSI EVS disks, determine whether you need to install the driver:</p>
-<ul id="en-us_topic_0052554220__ul125718469126"><li id="en-us_topic_0052554220__li112551546101214">Public Windows images are preinstalled with the Paravirtual SCSI (PVSCSI) driver. Therefore, no driver needs to be installed.</li><li id="en-us_topic_0052554220__li1925720462125">Private Windows images are not preinstalled with the PVSCSI driver. You need to download and install it explicitly.<p id="en-us_topic_0052554220__p1125774601215"><a name="en-us_topic_0052554220__li1925720462125"></a><a name="li1925720462125"></a>For details, see <strong id="en-us_topic_0052554220__b197472496177">(Optional) Optimizing Windows Private Images</strong> in the <em id="en-us_topic_0052554220__i1873689544203436">Image Management Service User Guide</em>.</p>
-</li><li id="en-us_topic_0052554220__li132574468125">Linux images are not preinstalled with the PVSCSI driver. You need to obtain the source code of the open-source Linux driver at <a href="https://github.com/UVP-Tools/SAP-HANA-Tools" target="_blank" rel="noopener noreferrer">https://github.com/UVP-Tools/SAP-HANA-Tools</a>, compile the code, and then install the driver.<p id="en-us_topic_0052554220__p19795173199">Note that this driver is different from the PVSCSI drivers attached to some Linux distributions.</p>
+</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li150525682717">Xen ECS<p id="en-us_topic_0052554220__en-us_topic_0078247521_p187715594275"><a name="en-us_topic_0052554220__en-us_topic_0078247521_li150525682717"></a><a name="en-us_topic_0078247521_li150525682717"></a>Due to driver limitations, you are advised not to use SCSI EVS disk with Xen ECSs.</p>
+<div class="p" id="en-us_topic_0052554220__en-us_topic_0078247521_p1138811165919">However, a few Windows and Linux images support SCSI EVS disks on Xen ECSs. For the supported images, see <a href="#en-us_topic_0052554220__en-us_topic_0078247521_table36381951181116">Table 1</a>.<div class="note" id="en-us_topic_0052554220__en-us_topic_0078247521_note225774621212"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="en-us_topic_0052554220__en-us_topic_0078247521_p343064525713">After confirming that the OS images of Xen ECSs support SCSI EVS disks, determine whether you need to install the driver:</p>
+<ul id="en-us_topic_0052554220__en-us_topic_0078247521_ul125718469126"><li id="en-us_topic_0052554220__en-us_topic_0078247521_li112551546101214">Public Windows images are preinstalled with the Paravirtual SCSI (PVSCSI) driver. Therefore, no driver needs to be installed.</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li1925720462125">Private Windows images are not preinstalled with the PVSCSI driver. You need to download and install it explicitly.<p id="en-us_topic_0052554220__en-us_topic_0078247521_p1125774601215"><a name="en-us_topic_0052554220__en-us_topic_0078247521_li1925720462125"></a><a name="en-us_topic_0078247521_li1925720462125"></a>For details, see <strong id="en-us_topic_0052554220__en-us_topic_0078247521_b197472496177">(Optional) Optimizing Windows Private Images</strong> in the <em id="en-us_topic_0052554220__en-us_topic_0078247521_i1873689544203436">Image Management Service User Guide</em>.</p>
+</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li132574468125">Linux images are not preinstalled with the PVSCSI driver. You need to obtain the source code of the open-source Linux driver at <a href="https://github.com/UVP-Tools/SAP-HANA-Tools" target="_blank" rel="noopener noreferrer">https://github.com/UVP-Tools/SAP-HANA-Tools</a>, compile the code, and then install the driver.<p id="en-us_topic_0052554220__en-us_topic_0078247521_p19795173199">Note that this driver is different from the PVSCSI drivers attached to some Linux distributions.</p>
 </li></ul>
 </div></div>
 </div>
-<div class="p" id="en-us_topic_0052554220__p368524671211">
-<div class="tablenoborder"><a name="en-us_topic_0052554220__table36381951181116"></a><a name="table36381951181116"></a><table cellpadding="4" cellspacing="0" summary="" id="en-us_topic_0052554220__table36381951181116" frame="border" border="1" rules="all"><caption><b>Table 1 </b>OSs supporting SCSI EVS disks</caption><thead align="left"><tr id="en-us_topic_0052554220__row763875110110"><th align="left" class="cellrowborder" valign="top" id="mcps1.3.3.3.1.3.3.1.2.4.1.1"><p id="en-us_topic_0052554220__p563819518115">Virtualization Type</p>
+<div class="p" id="en-us_topic_0052554220__en-us_topic_0078247521_p368524671211">
+<div class="tablenoborder"><a name="en-us_topic_0052554220__en-us_topic_0078247521_table36381951181116"></a><a name="en-us_topic_0078247521_table36381951181116"></a><table cellpadding="4" cellspacing="0" summary="" id="en-us_topic_0052554220__en-us_topic_0078247521_table36381951181116" frame="border" border="1" rules="all"><caption><b>Table 1 </b>OSs supporting SCSI EVS disks</caption><thead align="left"><tr id="en-us_topic_0052554220__en-us_topic_0078247521_row763875110110"><th align="left" class="cellrowborder" valign="top" id="mcps1.3.3.3.1.3.3.1.2.4.1.1"><p id="en-us_topic_0052554220__en-us_topic_0078247521_p563819518115">Virtualization Type</p>
 </th>
-<th align="left" class="cellrowborder" colspan="2" valign="top" id="mcps1.3.3.3.1.3.3.1.2.4.1.2"><p id="en-us_topic_0052554220__p1063875115119">OS</p>
+<th align="left" class="cellrowborder" colspan="2" valign="top" id="mcps1.3.3.3.1.3.3.1.2.4.1.2"><p id="en-us_topic_0052554220__en-us_topic_0078247521_p1063875115119">OS</p>
 </th>
 </tr>
 </thead>
-<tbody><tr id="en-us_topic_0052554220__row11638105113112"><td class="cellrowborder" rowspan="2" valign="top" width="19.89%" headers="mcps1.3.3.3.1.3.3.1.2.4.1.1 "><p id="en-us_topic_0052554220__p7638195161116">Xen</p>
+<tbody><tr id="en-us_topic_0052554220__en-us_topic_0078247521_row11638105113112"><td class="cellrowborder" rowspan="2" valign="top" width="19.89%" headers="mcps1.3.3.3.1.3.3.1.2.4.1.1 "><p id="en-us_topic_0052554220__en-us_topic_0078247521_p7638195161116">Xen</p>
 </td>
-<td class="cellrowborder" valign="top" width="15.129999999999999%" headers="mcps1.3.3.3.1.3.3.1.2.4.1.2 "><p id="en-us_topic_0052554220__p263835113111">Windows</p>
+<td class="cellrowborder" valign="top" width="15.129999999999999%" headers="mcps1.3.3.3.1.3.3.1.2.4.1.2 "><p id="en-us_topic_0052554220__en-us_topic_0078247521_p263835113111">Windows</p>
 </td>
-<td class="cellrowborder" valign="top" width="64.98%" headers="mcps1.3.3.3.1.3.3.1.2.4.1.2 "><p id="en-us_topic_0052554220__p18638165141112">See the Windows images listed on the <strong id="en-us_topic_0052554220__b842352706163839">Public Images</strong> page.</p>
-<p id="en-us_topic_0052554220__p3638145181116">Log in to the management console, choose <strong id="en-us_topic_0052554220__b842352706114953">Image Management Service</strong>, click the <strong id="en-us_topic_0052554220__b84235270611508">Public Images</strong> tab, and select <strong id="en-us_topic_0052554220__b842352706164154">ECS image</strong> and <strong id="en-us_topic_0052554220__b842352706164159">Windows</strong> from the drop-down lists, respectively.</p>
+<td class="cellrowborder" valign="top" width="64.98%" headers="mcps1.3.3.3.1.3.3.1.2.4.1.2 "><p id="en-us_topic_0052554220__en-us_topic_0078247521_p18638165141112">See the Windows images listed on the <strong id="en-us_topic_0052554220__en-us_topic_0078247521_b842352706163839">Public Images</strong> page.</p>
+<p id="en-us_topic_0052554220__en-us_topic_0078247521_p3638145181116">Log in to the management console, choose <strong id="en-us_topic_0052554220__en-us_topic_0078247521_b842352706114953">Image Management Service</strong>, click the <strong id="en-us_topic_0052554220__en-us_topic_0078247521_b84235270611508">Public Images</strong> tab, and select <strong id="en-us_topic_0052554220__en-us_topic_0078247521_b842352706164154">ECS image</strong> and <strong id="en-us_topic_0052554220__en-us_topic_0078247521_b842352706164159">Windows</strong> from the drop-down lists, respectively.</p>
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-<tr id="en-us_topic_0052554220__row16638165131113"><td class="cellrowborder" valign="top" headers="mcps1.3.3.3.1.3.3.1.2.4.1.1 "><p id="en-us_topic_0052554220__p1163845116114">Linux</p>
+<tr id="en-us_topic_0052554220__en-us_topic_0078247521_row16638165131113"><td class="cellrowborder" valign="top" headers="mcps1.3.3.3.1.3.3.1.2.4.1.1 "><p id="en-us_topic_0052554220__en-us_topic_0078247521_p1163845116114">Linux</p>
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-<td class="cellrowborder" valign="top" headers="mcps1.3.3.3.1.3.3.1.2.4.1.2 "><ul id="en-us_topic_0052554220__ul18638135151113"><li id="en-us_topic_0052554220__li19638165115119">SUSE Linux Enterprise Server 11 SP4 64bit (The kernel version is 3.0.101-68-default or 3.0.101-80-default.)</li><li id="en-us_topic_0052554220__li166381851111116">SUSE Linux Enterprise Server 12 64bit (The kernel version is 3.12.51-52.31-default.)</li><li id="en-us_topic_0052554220__li106381951201118">SUSE Linux Enterprise Server 12 SP1 64bit (The kernel version is 3.12.67-60.64.24-default.)</li><li id="en-us_topic_0052554220__li1663825131115">SUSE Linux Enterprise Server 12 SP2 64bit (The kernel version is 4.4.74-92.35.1-default.)</li></ul>
+<td class="cellrowborder" valign="top" headers="mcps1.3.3.3.1.3.3.1.2.4.1.2 "><ul id="en-us_topic_0052554220__en-us_topic_0078247521_ul18638135151113"><li id="en-us_topic_0052554220__en-us_topic_0078247521_li19638165115119">SUSE Linux Enterprise Server 11 SP4 64bit (The kernel version is 3.0.101-68-default or 3.0.101-80-default.)</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li166381851111116">SUSE Linux Enterprise Server 12 64bit (The kernel version is 3.12.51-52.31-default.)</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li106381951201118">SUSE Linux Enterprise Server 12 SP1 64bit (The kernel version is 3.12.67-60.64.24-default.)</li><li id="en-us_topic_0052554220__en-us_topic_0078247521_li1663825131115">SUSE Linux Enterprise Server 12 SP2 64bit (The kernel version is 4.4.74-92.35.1-default.)</li></ul>
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