This topic describes the performance metrics and specifications of various Elastic Block Storage (EBS) devices, such as cloud disks and local disks.

Performance metrics

The key metrics used to measure the performance of EBS devices include input/output operations per second (IOPS), throughput, and latency. Some EBS devices also have capacity requirements. For example, enhanced SSDs (ESSDs) at different performance levels (PLs) have different capacity ranges.

  • IOPS

    IOPS measures the number of read/write operations that can be performed per second. High IOPS is critical for transaction-intensive applications such as databases. A standard SSD can deliver the committed IOPS performance only when it is attached to an I/O optimized instance. For more information about I/O optimized instances, see Instance families. The following table describes the common IOPS metrics.

    Metric Description Data access method
    Total IOPS The total number of I/O operations per second. Access locations on storage devices in a continuous or non-continuous manner.
    Random read IOPS The average number of random read I/O operations per second. Access locations on storage devices in a non-continuous manner.
    Random write IOPS The average number of random write I/O operations per second.
    Sequential read IOPS The average number of sequential read I/O operations per second. Access locations on storage devices in a continuous manner.
    Sequential write IOPS The average number of sequential write I/O operations per second.
  • Throughput

    Throughput measures the amount of data transferred per second. Unit: MB/s. High throughput is critical for applications such as Hadoop offline computing applications that require a large number of sequential read/write operations.

  • Latency
    Latency measures the amount of time required for an EBS device to process an I/O request. Unit: seconds, milliseconds, or microseconds. High latency may cause performance to degrade or lead to errors in applications that require low latency.
    • For latency-sensitive applications such as databases, we recommend that you use ESSDs, standard SSDs, or local SSDs.
    • For applications such as Hadoop offline computing applications that require high throughput but not low latency, we recommend that you use Elastic Compute Service (ECS) instances of the d1 or d1ne instance family that have local SATA HDDs attached.
  • Capacity

    Capacity is the size of storage space. Unit: TiB, GiB, MiB, or KiB. EBS capacity is measured in binary units. For example, 1 GiB equals 1,024 MiB.

    You cannot use capacity as a metric to measure the performance of EBS devices. However, the performance of EBS devices varies based on their capacity. The larger the capacity of an EBS device is, the stronger its processing capabilities are. EBS devices of the same type have the same I/O performance per unit capacity. However, the performance of each cloud disk increases based on capacity until the maximum performance of a single disk of the corresponding category is reached. ESSDs of different capacity ranges have different PLs.

For more information about how to test the performance of different types of EBS devices, see Test the performance of Elastic Block Storage devices or Test the IOPS performance of an ESSD.

Disk performance

The following table describes the performance and typical use scenarios of different categories of disks.
Item ESSD Standard SSD Ultra disk Basic disk
PL PL3 PL2 PL1 PL0 N/A N/A N/A
Maximum capacity of a single disk (GiB) 1,261 to 32,768 461 to 32,768 20 to 32,768 40 to 32,768 32,768 32,768 2,000
Maximum IOPS 1,000,000 100,000 50,000 10,000 25,000 5,000 Several hundreds
Maximum throughput (MB/s) 4,000 750 350 180 300 140 30 to 40
Formula used to calculate the IOPS of a single disk min{1800 + 50 × Capacity, 1000000} min{1800 + 50 × Capacity, 100000} min{1800 + 50 × Capacity, 50000} min{1800 + 12 × Capacity, 10000} min{1800 + 30 × Capacity, 25000} min{1800 + 8 × Capacity, 5000} None
Formula used to calculate the throughput of a single disk (MB/s) min{120 + 0.5 × Capacity, 4000} min{120 + 0.5 × Capacity, 750} min{120 + 0.5 × Capacity, 350} min{100 + 0.25 × Capacity, 180} min{120 + 0.5 × Capacity, 300} min{100 + 0.15 × Capacity, 140} None
Data durability 99.9999999% 99.9999999% 99.9999999% 99.9999999% 99.9999999% 99.9999999% 99.9999999%
Average single-channel random write latency in milliseconds, with a block size of 4 KB 0.2 0.3 to 0.5 0.5 to 2 1 to 3 5 to 10
API parameter value cloud_essd cloud_ssd cloud_efficiency cloud
Use scenario
  • Large online transaction processing (OLTP) databases: relational databases such as MySQL, PostgreSQL, Oracle, and SQL Server databases
  • NoSQL databases: non-relational databases such as MongoDB, HBase, and Cassandra databases
  • Elasticsearch distributed logs: Elasticsearch, Logstash, and Kibana (ELK) log analysis
  • I/O-intensive applications
  • Small and medium-sized relational databases
  • NoSQL databases
  • Development and test business
  • System disks
  • Applications that are not frequently accessed or have low I/O loads
  • Applications that require low costs and random I/O operations

The performance of standard SSDs varies based on the sizes of data blocks. Smaller data blocks result in lower throughput and higher IOPS, as described in the following table.

Data block size (KiB) Maximum IOPS Throughput (MB/s)
4 Approximately 25,000 Approximately 100
16 Approximately 17,200 Approximately 260
32 Approximately 9,600 Approximately 300
64 Approximately 4,800 Approximately 300

In the following examples, a standard SSD is used to describe how to calculate the performance of a single disk:

  • Maximum IOPS: The baseline IOPS is 1,800. The performance increases by 30 IOPS per additional GiB of storage. The maximum IOPS is 25,000.
  • Maximum throughput: The baseline throughput is 120 MB/s. The performance increases by 0.5 MB/s per additional GiB of storage. The maximum throughput is 300 MB/s.

Basic disks are part of a previous generation of disks and are no longer available for purchase.

Performance of local disks

For more information about the performance of local NVMe SSDs and SATA HDDs, see Local disks.