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Amazon Elastic Compute Cloud
User Guide for Linux Instances

Amazon EC2 Instance Store

An instance store provides temporary block-level storage for your instance. This storage is located on disks that are physically attached to the host computer. Instance store is ideal for temporary storage of information that changes frequently, such as buffers, caches, scratch data, and other temporary content, or for data that is replicated across a fleet of instances, such as a load-balanced pool of web servers.

An instance store consists of one or more instance store volumes exposed as block devices. The size of an instance store varies by instance type. The virtual devices for instance store volumes are ephemeral[0-23]. Instance types that support one instance store volume have ephemeral0. Instance types that support two instance store volumes have ephemeral0 and ephemeral1, and so on. While an instance store is dedicated to a particular instance, the disk subsystem is shared among instances on a host computer.

Amazon EC2 instance storage

Instance Store Lifetime

You can specify instance store volumes for an instance only when you launch it, though you may be able to resize an instance and add additional ephemeral storage during that process. For information about resizing instances, see Resizing Your Instance.

The data in an instance store persists only during the lifetime of its associated instance. If an instance reboots (intentionally or unintentionally), data in the instance store persists. However, data in the instance store is lost under the following circumstances:

  • The underlying disk drive fails

  • The instance stops

  • The instance terminates

Therefore, do not rely on instance store for valuable, long-term data. Instead, you can build a degree of redundancy (for example, RAID 1/5/6), or use a file system (for example, HDFS and MapR-FS) that supports redundancy and fault tolerance. You can also back up data periodically to more durable data storage solutions such as Amazon S3 or Amazon EBS.

You can't detach an instance store volume from one instance and attach it to a different instance. If you create an AMI from an instance, the data on its instance store volumes isn't preserved and isn't present on the instance store volumes of the instances that you launch from the AMI.

Instance Store Volumes

The instance type determines the size of the instance store available and the type of hardware used for the instance store volumes. Instance store volumes are included as part of the instance's hourly cost. You must specify the instance store volumes that you'd like to use when you launch the instance, and then format and mount them before using them. You can't make an instance store volume available after you launch the instance. For more information, see Add Instance Store Volumes to Your EC2 Instance.

Some instance types use solid state drives (SSD) to deliver very high random I/O performance. This is a good option when you need storage with very low latency, but you don't need the data to persist when the instance terminates or you can take advantage of fault-tolerant architectures. For more information, see SSD Instance Store Volumes.

The following table provides the quantity, size, type, and performance optimizations of instance store volumes available on each supported instance type. For a complete list of instance types, including EBS-only types, see Amazon EC2 Instance Types.

Instance TypeInstance Store VolumesTypeNeeds Initialization*TRIM Support**

c1.medium

1 x 350 GB

HDD 

c1.xlarge

4 x 420 GB (1,680 GB)

HDD 

c3.large

2 x 16 GB (32 GB)

SSD 

c3.xlarge

2 x 40 GB (80 GB)

SSD 

c3.2xlarge

2 x 80 GB (160 GB)

SSD 

c3.4xlarge

2 x 160 GB (320 GB)

SSD 

c3.8xlarge

2 x 320 GB (640 GB)

SSD 

cc2.8xlarge

4 x 840 GB (3,360 GB)

HDD 

cg1.4xlarge

2 x 840 GB (1,680 GB)

HDD 

cr1.8xlarge

2 x 120 GB (240 GB)

SSD 

d2.xlarge

3 x 2,000 GB (6 TB)

HDD  

d2.2xlarge

6 x 2,000 GB (12 TB)

HDD  

d2.4xlarge

12 x 2,000 GB (24 TB)

HDD  

d2.8xlarge

24 x 2,000 GB (48 TB)

HDD  
g2.2xlarge1 x 60 GBSSD 
g2.8xlarge2 x 120 GB (240 GB)SSD 

hi1.4xlarge

2 x 1,024 GB (2,048 GB)

SSD  

hs1.8xlarge

24 x 2,000 GB (48 TB)

HDD 

i2.xlarge

1 x 800 GB

SSD 

i2.2xlarge

2 x 800 GB (1,600 GB)

SSD 

i2.4xlarge

4 x 800 GB (3,200 GB)

SSD 

i2.8xlarge

8 x 800 GB (6,400 GB)

SSD 

m1.small

1 x 160 GB

HDD 

m1.medium

1 x 410 GB

HDD 

m1.large

2 x 420 GB (840 GB)

HDD 

m1.xlarge

4 x 420 GB (1,680 GB)

HDD 

m2.xlarge

1 x 420 GB

HDD 

m2.2xlarge

1 x 850 GB

HDD 

m2.4xlarge

2 x 840 GB (1,680 GB)

HDD 

m3.medium

1 x 4 GB

SSD 

m3.large

1 x 32 GB

SSD 

m3.xlarge

2 x 40 GB (80 GB)

SSD 

m3.2xlarge

2 x 80 GB (160 GB)

SSD 

r3.large

1 x 32 GB

SSD 

r3.xlarge

1 x 80 GB

SSD 

r3.2xlarge

1 x 160 GB

SSD 

r3.4xlarge

1 x 320 GB

SSD 

r3.8xlarge

2 x 320 GB (640 GB)

SSD 
x1.16xlarge1 x 1,920 GBSSD  
x1.32xlarge2 x 1,920 GB (3,840 GB)SSD  

* Volumes attached to certain instances will suffer a first-write penalty unless initialized. For more information about initializing instance store volumes, see Optimizing Disk Performance for Instance Store Volumes.

** SSD-based instance store volumes that support TRIM instructions are not pre-formatted with any file system. However, you can format volumes with the file system of your choice after you launch your instance. For more information, see Instance Store Volume TRIM Support.

† The c1.medium and m1.small instance types also include a 900 MB instance store swap volume, which may not be automatically enabled at boot time. For more information, see Instance Store Swap Volumes.