# Large-Memory ECSs

#### Overview

Large-memory ECSs provide an even larger amount of memory than memory-optimized ECSs. They are used for applications that require a large amount of memory, rapid data switching, low latency, and process large volumes of data. Large-memory ECSs provide large memory and high computing, storage, and network performance.

- Applications

  Large-memory ECSs are suitable for applications that require a large amount of memory, rapid data switching, and low latency, and process large volumes of data.

- Application scenarios

  E3 ECSs: OLAP and OLTP applications with hyper-threading enabled

#### Specifications

Table 1 E3 ECS specifications
Flavor | vCPUs | Memory (GiB) | Maximum/Assured Bandwidth (Gbit/s) | Maximum PPS (10,000) | NIC Multi-Queue | Virtualization Type | Hardware
--- | --- | --- | --- | --- | --- | --- | ---
e3.7xlarge.12 | 28 | 348 | 25/12 | 280 | 8 | KVM | CPU: Intel® Xeon® Skylake 6151
e3.14xlarge.12 | 56 | 696 | 25/25 | 500 | 16 | KVM

#### Notes

- Large-memory ECSs do not support NIC hot swapping.
- E3 ECSs support the following OSs that have been verified:

  SUSE Enterprise Linux Server 12 SP2 64bit

  SUSE Enterprise Linux Server 12 SP3 64bit

- E3 ECSs can use ultra-high I/O EVS disks as the system disk and data disks.
- The primary and extension NICs of a large-memory ECS have specified application scenarios. For details, see Table 2.

  Table 2 Application scenarios of the NICs of a large-memory ECS
  NIC Type | Application Scenario | Remarks
  --- | --- | ---
  Primary NIC | Vertical layer 3 communication | N/A
  Extension NIC | Horizontal layer 2 communication | To improve network performance, you can set the MTU of an extension NIC to 8888.

- An ECS can have a maximum of 60 attached disks, including the system disk. For details about constraints, see Can I Attach Multiple Disks to an ECS?

  An example is provided as follows:

  An E3 ECS is to be created. It can have a maximum of 60 attached disks, where:

  - The number of system disks is 1.
  - The number of EVS disks is at most 59.

  The maximum number of disks attached to an existing large-memory ECS remains unchanged. To attach 60 disks, enable advanced disk. For details, see Enabling Advanced Disk.

Parent topic: ECS Specifications and Types