Amazon EBS FAQs

Q: Are Amazon EBS volume and snapshot ID lengths changing in 2018?

Yes, please visit the EC2 FAQs page for more details.

Q: What happens to my data when an Amazon EC2 instance terminates?

Unlike the data stored on a local instance store (which persists only as long as that instance is alive), data stored on an Amazon EBS volume can persist independently of the life of the instance. Therefore, we recommend that you use the local instance store only for temporary data. For data requiring a higher level of durability, we recommend using Amazon EBS volumes or backing up the data to Amazon S3. If you are using an Amazon EBS volume as a root partition, set the Delete on termination flag to "No" if you want your Amazon EBS volume to persist outside the life of the instance.

Q: What kind of performance can I expect from Amazon EBS volumes?

Amazon EBS provides four volume types: Provisioned IOPS SSD (io1), General Purpose SSD (gp2), Throughput Optimized HDD (st1) and Cold HDD (sc1). These volume types differ in performance characteristics and price, allowing you to tailor your storage performance and cost to the needs of your applications. The average latency between EC2 instances and EBS is single digit milliseconds. For more performance information see the EBS product details page.

For more information about Amazon EBS performance guidelines, see Increasing EBS Performance.

Q: Which volume should I choose?

Amazon EBS includes two major categories of storage: SSD-backed storage for transactional workloads (performance depends primarily on IOPS, latency, and durability) and HDD-backed storage for throughput workloads (performance depends primarily on throughput, measured in MB/s). SSD-backed volumes are designed for transactional, IOPS-intensive database workloads, boot volumes, and workloads that require high IOPS. SSD-backed volumes include Provisioned IOPS SSD (io1) and General Purpose SSD (gp2). HDD-backed volumes are designed for throughput-intensive and big-data workloads, large I/O sizes, and sequential I/O patterns. HDD-backed volumes include Throughput Optimized HDD (st1) and Cold HDD (sc1).

Q: How do I modify the capacity, performance, or type of an existing EBS volume?

Changing a volume configuration is easy. The Elastic Volumes feature allows you to increase capacity, tune performance, or change your volume type with a single CLI call, API call or a few console clicks. For more information about Elastic Volumes, see the Elastic Volumes documentation.

Q: Are EBS Standard Volumes still available?

EBS Standard Volumes have been renamed to EBS Magnetic volumes. Any existing volumes will not have been changed as a result of this and there are no functional differences in the EBS Magnetic offering compared to EBS Standard. The name of this offering was changed to avoid confusion with our General Purpose SSD (gp2) volume type which is our recommended default volume type.

Q: Are Provisioned IOPS SSD (io1) volumes available for all Amazon EC2 instance types?

Yes, Provisioned IOPS SSD (io1) volumes are available for all Amazon EC2 Instance Types. Use EBS optimized EC2 instances to deliver consistent and predictable IOPS on io1 volumes. EBS-optimized instances deliver dedicated throughput between Amazon EC2 and Amazon EBS, with options between 62.5 MB/s and 4,750 MB/s depending on the instance type used. To achieve the limit of 64,000 IOPS and 1,000 MB/s throughput, the volume must be attached to a Nitro System-based EC2 instance.

Q: What level of performance consistency can I expect to see from my Provisioned IOPS SSD (io1) volumes?

When attached to EBS-optimized instances, Provisioned IOPS SSD (io1) volumes are designed to deliver within 10% of the provisioned IOPS performance 99.9% of the time in a given year. Your exact performance depends on your application’s I/O requirements.

Q: What level of performance latency can I expect to see from my Provisioned IOPS SSD (io1) volumes?

When attached to EBS-optimized instances, Provisioned IOPS volumes can achieve single digit millisecond latencies. Your exact performance depends on your application’s I/O requirements.

Q: Does the I/O size of my application reads and writes affect the rate of IOPS I get from my Provisioned IOPS SSD (io1) volumes?

Yes, it does. When you provision IOPS for io1 volumes, the IOPS rate you get depends on the I/O size of your application reads and writes. Provisioned IOPS volumes have a base I/O size of 16KB. So, if you have provisioned a volume with 40,000 IOPS for an I/O size of 16KB, it will achieve up to 40,000 IOPS at that size. If the I/O size is increased to 32 KB, then you will achieve up to 20,000 IOPS, and so on. For more details, please visit technical documentation on Provisioned IOPS volumes. You can use Amazon CloudWatch to monitor your throughput and I/O sizes.

Q: What factors can affect the performance consistency I see with Provisioned IOPS SSD (io1) volumes?

Provisioned IOPS SSD (io1) volumes attached to EBS-optimized instances are designed to offer consistent performance, delivering within 10% of the provisioned IOPS performance 99.9% of the time over a given year. For maximum performance consistency with new volumes created from a snapshot, we recommend enabling Fast Snapshot Restore (FSR) on your snapshots. EBS volumes restored from FSR-enabled snapshots instantly receive their full performance.

Another factor that can impact your performance is if your application isn’t sending enough I/O requests. This can be monitored by looking at your volume’s queue depth. The queue depth is the number of pending I/O requests from your application to your volume. For maximum consistency, a Provisioned IOPS volume must maintain an average queue depth (rounded to the nearest whole number) of one for every 1000 provisioned IOPS in a minute. For example, for a volume provisioned with 3000 IOPS, the queue depth average must be 3. For more information about ensuring consistent performance of your volumes, see Increasing EBS Performance.

Q: What level of performance consistency can I expect to see from my HDD-backed volumes?

When attached to EBS-optimized instances, Throughput Optimized HDD (st1) and Cold HDD (sc1) volumes are designed to deliver within 10% of the expected throughput performance 99% of the time in a given year. Your exact performance depends on your application’s I/O requirements and the performance of your EC2 instance.

Q: Does the I/O size of my application reads and writes affect the rate of throughput I get from my HDD-backed volumes?

Yes. The throughput rate you get depends on the I/O size of your application reads and writes. HDD-backed volumes process reads and writes in I/O sizes of 1MB. Sequential I/Os are merged and processed as 1 MB units while each non-sequential I/O is processed as 1MB even if the actual I/O size is smaller. Thus, while a transactional workload with small, random IOs, such as a database, won't perform well on HDD-backed volumes, sequential I/Os and large I/O sizes will achieve the advertised performance of st1 and sc1 for a longer period of time.

Q: What factors can affect the performance consistency of my HDD-backed volumes?

Throughput Optimized HDD (st1) and Cold HDD (sc1) volumes attached to EBS-optimized instances are designed to offer consistent performance, delivering within 10% of the expected throughput performance 99% of the time in a given year. There are several factors that could affect the level of consistency you see. For example, the relative balance between random and sequential I/O operations on the volume can impact your performance. Too many random small I/O operations will quickly deplete your I/O credits and lower your performance down to the baseline rate. Your throughput rate may also be lower depending on the instance selected. Although st1 can drive throughput up to 500 MB/s, performance will be limited by the separate instance-level limit for EBS traffic. Another factor is taking a snapshot which will decrease expected write performance down to the baseline rate, until the snapshot completes. This is specific to st1 and sc1.

Your performance can also be impacted if your application isn’t sending enough I/O requests. This can be monitored by looking at your volume’s queue depth and I/O size. The queue depth is the number of pending I/O requests from your application to your volume. For maximum consistency, HDD-backed volumes must maintain an average queue depth (rounded to the nearest whole number) of four or more for every 1 MB sequential I/O. For more information about ensuring consistent performance of your volumes, see Increasing EBS Performance.

Q: Can I stripe multiple volumes together to get better performance?

Yes. You can stripe multiple volumes together to achieve up to 80,000 IOPS or 2,375 MiB/s when attached to larger EC2 instances. However, performance for st1 and sc1 scales linearly with volume size so there may not be as much of a benefit to stripe these volumes together.

Q: How does Amazon EBS handle issues like storage contention?

EBS is a multi-tenant block storage service. We employ rate limiting as a mechanism to avoid resource contention. This starts with having defined performance criteria for the volumes – our volume types (gp2, PIOPS, st1, and sc1) all have defined performance characteristics in terms of IOPS and throughput. The next step is defining performance at the instance level. Each EBS Optimized instance has defined performance (both throughput and IOPS) for the set of EBS volumes attached to the instance. A customer can, therefore, size instances and volumes to get the desired level of performance. In addition, customers can use our reported metrics to observe instance level and volume level performance. They can set alarms to determine if what they are seeing does not match the expected performance – the metrics can also help determine if customers are configured at the right type of instance with the right amount of performance at the volume level or not. On the EBS end, we use the configured performance to inform how we allocate the appropriate instance and EBS infrastructure to support the volumes. By appropriately allocating infrastructure, we avoid resource contention. Additionally, we constantly monitor our infrastructure. This monitoring allows us to detect infrastructure failure (or imminent infrastructure failure) and therefore, move the volumes pro-actively to functioning hardware while the underlying infrastructure is either repaired or replaced (as appropriate).

Q: What level of performance consistency can I expect to see from my General Purpose SSD (gp3 and gp2) volumes?

When attached to EBS-optimized instances, General Purpose SSD (gp3 and gp2) volumes are designed to deliver within 10% of the provisioned IOPS performance 99% of the time in a given year. Your exact performance depends on your application’s I/O requirements.

Q: What level of performance latency can I expect to see from my General Purpose SSD (gp3 and gp2) volumes?

When attached to EBS-optimized instances, General Purpose SSD (gp3 and gp2) volumes can achieve single digit millisecond latencies. Your exact performance depends on your application’s I/O requirements.

Q: Do General Purpose SSD (gp3) volumes have burst?

No. All General Purpose SSD (gp3) volumes include 3,000 IOPS and 125 MB/s of consistent performance at no additional cost. Volumes can sustain the full 3,000 IOPS and 125 MB/s indefinitely.

Q: How does burst work on General Purpose SSD (gp2) volumes?

General Purpose SSD (gp2) volumes that are under 1,000 GB receive burst IOPS performance up to 3,000 IOPS for at least 30 min of sustained performance. Additionally, gp2 volumes deliver consistent performance of 3 IOPS per provisioned GB. For example, a 500 GB volume is capable of driving 1,500 IOPS consistently, and bursting to 3,000 IOPS for 60 minutes (3,000 IOPS * 60 seconds * 30 minutes / 1,500 IOPS / 60 seconds).

Q: How can I use EBS direct APIs for Snapshots?

This feature can be used via the following APIs that can be called using Amazon CLI or via Amazon SDK.

• List Snapshot Blocks: The ListSnapshotBlocks API operation returns the block indexes and block tokens for blocks in the specified snapshot.
• List Changed Blocks: The ListChangedBlocks API operation returns the block indexes and block tokens for blocks that are different between two specified snapshots of the same volume/snapshot lineage.
• Get Snapshot Blocks: The GetSnapshotBlock API operation returns the data in a block for the specified snapshot ID, block index, and block token.
• Start Snapshot: The StartSnapshot operation starts a snapshot, either as an incremental snapshot of an existing one or as a new snapshot. The started snapshot remains in a pending state until it is completed using the CompleteSnapshot action.
• Put Snapshot Block: The PutSnapshot operation adds data in the form of individual blocks to a started snapshot that is in a pending state. You must specify a Base64-encoded SHA256 checksum for the block of data transmitted. The service validates the checksum after the transmission is completed. The request fails if the checksum computed by service doesn’t match what you specified.
• Complete Snapshot: The CompleteSnapshot operation completes a started snapshot that is in a pending state. The snapshot is then changed to a completed state.

For more information, please refer to technical documentation.

Q: What block sizes are supported by GetSnapshotBlock and PutSnapshotBlock APIs?

GetSnapshotBlock and PutSnapshotBlock APIs support 512KiB block size.

Q: Will I be able to access my snapshots using the regular Amazon S3 API?

No, snapshots are only available through the Amazon EC2 API.

Q: Do volumes need to be un-mounted to take a snapshot?

No, snapshots can be done in real time while the volume is attached and in use. However, snapshots only capture data that has been written to your Amazon EBS volume, which might exclude any data that has been locally cached by your application or OS. To ensure consistent snapshots on volumes attached to an instance, we recommend detaching the volume cleanly, issuing the snapshot command, and then reattaching the volume. For Amazon EBS volumes that serve as root devices, we recommend shutting down the machine to take a clean snapshot.

Q: Does it take longer to snapshot an entire 16 TB volume as compared to an entire 1 TB volume?

By design, an EBS Snapshot of an entire 16 TB volume should take no longer than the time it takes to snapshot an entire 1 TB volume. However, the actual time taken to create a snapshot depends on several factors including the amount of data that has changed since the last snapshot of the EBS volume.

Q: Are snapshots versioned? Can I read an older snapshot to do a point-in-time recovery?

Each snapshot is given a unique identifier, and customers can create volumes based on any of their existing snapshots.

Q: How can I discover Amazon EBS snapshots that are shared with me?

You can find snapshots that are shared with you by selecting Private Snapshots from the list in the Snapshots section of the Amazon Web Services Management Console. This section lists both snapshots that you own and snapshots that are shared with you.

Q: How can I find which Amazon EBS snapshots are shared globally?

You can find snapshots that are shared globally by selecting Public Snapshots from the list in the Snapshots section of the Amazon Web Services Management Console. You can also restrict public access to snapshots in an account by enabling Block Public Access for EBS Snapshots. 

Q: How can I find a list of Amazon public datasets stored in Amazon EBS Snapshots?

You can use the Amazon Web Services Management Console to find public datasets stored as Amazon Snapshots. Log into the console, select the Amazon EC2 Service, select Snapshots and then filter on Public Snapshots.

Q: When would I use Fast Snapshot Restore (FSR)?

You should enable FSR on snapshots if you are concerned about latency of data access when you restore data from a snapshot to a volume and want to avoid the initial performance hit during initialization. FSR is intended to help with use cases such as virtual desktop infrastructure (VDI), backup & restore, test/dev volume copies, and booting from custom AMIs. By enabling FSR on your snapshot, you will see improved and predictable performance whenever you need to restore data from that snapshot.

Q: Does enabling FSR for my snapshot speed up snapshot creation?

No. FSR-enabled snapshots improve restoring backup data from your snapshot to your volumes. FSR-enabled snapshots do not speed up snapshot creation time.

Q: How do I enable Fast Snapshot Restore (FSR)?

To use the feature, invoke the new enable-fast-snapshot-restores API on a snapshot within the availability zone (AZ) where initialized volumes are to be restored.
The FSR-enabled snapshot may be in any one of the following states: enabling, optimizing, enabled, disabling, disabled. State transitions are published as CloudWatch events and the FSR state can be checked via the describe-fast-snapshot-restores API.
Enabling FSR on a snapshot does not change any existing snapshot API interactions, and existing workflows will not need to change. FSR can be enabled or disabled on account-owned snapshots only. FSR cannot be applied to shared snapshots. You can view the list of your FSR-enabled snapshots via API or the console.

Q: How do I use Fast Snapshot Restore (FSR)?

Volumes created from an FSR-enabled snapshot are fully initialized. However, there are limits on the number of volumes that can be created with immediate full performance. These limits are expressed in the form of a credit bucket that is associated with an FSR-enabled snapshot in a given AZ. The important things to know regarding credits:

1. A single volume create operation consumes a single credit
2. The number of credits is a function of the FSR-enabled snapshot size
3. Credits refill over time
4. Maximum credit bucket size is 10

To estimate your credit bucket size and fill rate, divide 1,024 by your snapshot size. For example, a 100 GiB FSR-enabled snapshot will have the maximum balance of 10 credits with a fill rate of 10 credits every hour. A 4 TiB snapshot will have a maximum balance of 1 with a fill rate of 1 credit every 4 hours.
It's important to note that the credit bucket size is a function of the FSR-enabled snapshot size, not the size of the volumes that are created. For example, it is possible to create up to ten 1TiB volumes from a 100GiB snapshot at once.

Lastly, each AZ in which the snapshot is FSR-enabled gets its own credit bucket independent of other AZs.

Q: How many concurrent volumes can I create and what happens when I surpass this limit?

The size of the create credit bucket represents the maximum number and the balance of the credit bucket represents the number of creates available. When filled, up to 10 initialized volumes can be created from an FSR-enabled snapshot at once. Both the maximum size of the credit bucket and the credit bucket balance are published as CloudWatch metrics. Volume creations beyond the limit will proceed as if FSR is not enabled on the snapshot.

Q: How do I know when a volume was created from an FSR-enabled snapshot?

When using FSR, a new EBS-specific attribute (fastRestored) is added in the DescribeVolumes API to denote the status at create time. When a volume is created from an FSR-enabled snapshot without sufficient volume-create credits, the create will succeed but the volume will not be initialized.

Q: What happens to FSR when I delete a snapshot?

When you delete a snapshot, the FSR for your snapshot is automatically disabled and FSR billing for the snapshot will be terminated.

Q: Can I enable FSR for public and private snapshots shared with me?

Yes, you can enable FSR for public snapshots as well as all private snapshots shared with your account. To enable FSR for shared snapshots, you can use the same set of API calls that you use for enabling FSR on snapshots you own.

Q: How am I billed for enabling FSR on a snapshot shared with me?

When you enable FSR on your shared snapshot, you will be billed at standard FSR rates (see pricing pages). Note that only your account will be billed for the FSR of the shared snapshot. The owner of the snapshot will not get billed when you enable FSR on the shared snapshot.

Q: What happens to the FSR for a shared snapshot when the owner of the snapshot stops sharing the snapshot or deletes it?

When the owner of your shared snapshot deletes the snapshot, or stops sharing the snapshot with you by revoking your permissions to create volumes from this snapshot, the FSR for your shared snapshot is automatically disabled and FSR billing for the snapshot will be terminated.

Q: What is Amazon EBS encryption?

Amazon EBS encryption offers seamless encryption of EBS data volumes, boot volumes and snapshots, eliminating the need to build and maintain a secure key management infrastructure. EBS encryption enables data at rest security by encrypting your data using Amazon-managed keys, or keys you create and manage using the Amazon Key Management Service (KMS). The encryption occurs on the servers that host EC2 instances, providing encryption of data as it moves between EC2 instances and EBS storage. For more details, see Amazon EBS encryption in the Amazon EC2 User Guide.

Q: What is the Amazon Key Management Service (KMS)?

Amazon KMS is a managed service that makes it easy for you to create and control the encryption keys used to encrypt your data. Amazon Key Management Service is integrated with other Amazon Web Services services including Amazon EBS, Amazon S3, and Amazon Redshift, to make it simple to encrypt your data with encryption keys that you manage. Amazon Key Management Service is also integrated with Amazon CloudTrail to provide you with logs of all key usage to help meet your regulatory and compliance needs. To learn more about KMS, visit the Amazon Key Management Service product page.

Q: Why should I use EBS encryption?

You can use Amazon EBS encryption to meet security and encryption compliance requirements for data at rest encryption in the cloud. Pairing encryption with existing IAM access control policies improves your company’s defense-in-depth strategy.

Q: How are my Amazon EBS encryption keys managed?

Amazon EBS encryption handles key management for you. Each newly created volume gets a unique 256-bit AES key; Volumes created from the encrypted snapshots share the key. These keys are protected by our own key management infrastructure, which implements strong logical and physical security controls to prevent unauthorized access. Your data and associated keys are encrypted using the industry-standard AES-256 algorithm.

Q: Does EBS encryption support boot volumes?

Yes.

Q: Can I create an encrypted data volume at the time of instance launch?

Yes, using customer master keys (CMKs) that are either Amazon Web Services-managed or customer-managed. You can specify the volume details and encryption through a RunInstances API call with the BlockDeviceMapping parameter or through the Launch Wizard in the EC2 Console.

Q: Can I create additional encrypted data volumes at the time of instance launch that are not part of the AMI?

Yes, you can create encrypted data volume with either default or custom CMK encryption at the time of instances launch. You can specify the volume details and encryption through BlockDeviceMapping object in RunInstances API call or through Launch Wizard in EC2 Console.

Q: Can I launch an encrypted EBS instance from an unencrypted AMI?

Yes. See technical documentation for details.

Q: Can I share encrypted snapshots and AMIs with other accounts?

Yes. You can share encrypted snapshots and AMIs using a customer-managed customer master key (CMK) with other Amazon Web Services accounts in China. See technical documentation for details.

Q: Can I ensure that all new volumes created are always encrypted?

Yes, you can enable EBS encryption by default with a single setting per region. This ensures that all new volumes are always encrypted. Refer to technical documentation for more details.

Q: Will I be billed for the IOPS provisioned on a Provisioned IOPS volume when it is disconnected from an instance?

Yes, you will be billed for the IOPS provisioned when it is disconnected from an instance. When a volume is detached, we recommend you consider creating a snapshot and deleting the volume to reduce costs. For more information, see the "Underutilized Amazon EBS Volumes" cost optimization check in Trusted Advisor. This item checks your Amazon Elastic Block Store (Amazon EBS) volume configurations and warns when volumes appear to be underused.