Local SSDs are no longer available for purchase. This topic is intended for users who still use local SSDs.

Local SSDs

Local SSDs are located on the physical servers that host their associated Elastic Compute Service (ECS) instances. Local SSDs provide block-level data access capabilities for the instances and feature low latency, high random IOPS, and high throughput.

When you use local SSDs, take note of the following items:
  • Local SSDs bring risks of single points of failure (SPOFs) because they are located on the physical servers that host their associated instances. We recommend that you implement data redundancy at the application layer to ensure the availability of data.
  • After you purchase an instance that uses local SSDs, you cannot upgrade or downgrade the configurations of the instance, such as the number of CPU cores, the memory size, and the specifications of the local SSDs.

Parameters

Parameter Local SSD
Maximum capacity 800 GB
Maximum IOPS 12000
Maximum throughput 250 MBps~300 MBps
Performance formula N/A
Access latency 0.5ms~2ms
Data durability The durability of data stored on local disks is determined by the reliability of the associated physical server. No service level agreement (SLA) compliance is guaranteed.
API parameter value ephemeral_ssd
Price For more information, seethe Pricing tab on the Elastic Compute Service product page.
Use scenario Distributed applications that require high reliability, low latency, and high storage I/O performance, such as Hadoop and NoSQL.

*The price described in the preceding table is the price in the China (Hangzhou) region. For more information, seethe Pricing tab on the Elastic Compute Service product page.

Features

Local SSDs are located on the physical servers that host their associated instances and provide storage capacities for the instances. Local SSDs have the following features:
  • Low latency: Local SSDs offer latency within microseconds.
  • High random I/O: Local SSDs deliver up to 12,000 random IOPS.
  • High throughput: Local SSDs provide I/O throughput of up to 300 MB/s.
  • Limited data durability: The durability of data stored on local SSDs is determined by the reliability of the associated physical server. In this case, risks of SPOFs may arise. We recommend that you implement data redundancy at the application layer to ensure the availability of data.
  • Storage capacity of up to 800 GB: A single local SSD can provide a storage capacity of up to 800 GB.
  • Local SSDs are located on physical servers and cannot be separately attached to or unattached from instances.
  • After you purchase an instance that uses local SSDs, you cannot upgrade or downgrade the configurations of the instance, such as the number of CPU cores, the memory size, and the specifications of the local SSDs.

Use scenarios

Local SSDs feature low latency, high random I/O, and high throughput. Local SSDs are applicable to distributed, I/O-intensive applications with redundancy capabilities and scenarios that do not require high data durability.
  • You can use local SSDs for distributed, I/O-intensive applications such as NoSQL databases, massively parallel processing (MPP) data warehouses, and distributed file systems. Data redundancy is implemented on the applications in a distributed manner. Local SSDs can provide low latency, high random I/O, and high I/O throughput for the applications.
  • You can use local SSDs to store the logs of large online applications. The applications can produce a large amount of log data and require high-performance storage. In addition, log data does not require highly reliable storage.
  • You can also use local SSDs as swap partitions in instances. When applications that run on a Linux instance require more memory but the amount of memory allocated to the applications is exhausted, you can enable the swap space. After the swap space is enabled, the Linux system can frequently swap in-use memory pages from the physical memory to the swap spaces regardless of whether they are dedicated partitions of the existing file systems or swap files. The Linux system can also free up space for memory pages that require high access speeds.

Local SSDs

Local SSDs are no longer available for purchase. If you have purchased and are still using local SSDs, note that local SSDs bring risks of SPOFs because they are located on the physical servers that host their associated instances. We recommend that you implement data redundancy at the application layer to ensure the availability of data.