Performance - AWS Storage Services Overview

Performance

The instance store volumes that are not SSD-based in most EC2 instance families have performance characteristics similar to standard EBS volumes. Because the EC2 instance virtual machine and the local instance store volumes are located on the same physical server, interaction with this storage is very fast, particularly for sequential access. To increase aggregate IOPS, or to improve sequential disk throughput, multiple instance store volumes can be grouped together using RAID 0 (disk striping) software. Because the bandwidth of the disks is not limited by the network, aggregate sequential throughput for multiple instance volumes can be higher than for the same number of EBS volumes.

Because of the way that EC2 virtualizes disks, the first write operation to any location on an instance store volume performs more slowly than subsequent writes. For most applications, amortizing this cost over the lifetime of the instance is acceptable. However, if you require high disk performance, we recommend that you prewarm your drives by writing once to every drive location before production use. The i2, r3, and hi1 instance types use direct-attached SSD backing that provides maximum performance at launch time without prewarming.

Additionally, r3 and i2 instance store-backed volumes support the TRIM command on Linux instances. For these volumes, you can use TRIM to notify the SSD controller whenever you no longer need data that you've written. This notification lets the controller free space, which can reduce write amplification and increase performance.

The SSD instance store volumes in EC2 high I/O instances provide from tens of thousands to hundreds of thousands of low-latency, random 4 KB random IOPS. Because of the I/O characteristics of SSD devices, write performance can be variable. For more information, see High I/O Instances in the Amazon EC2 User Guide.

The instance store volumes in EC2 high-storage instances provide very high storage density and high sequential read and write performance. For more information, see High Storage Instances in the Amazon EC2 User Guide.