Elastic Block Store
EBS is the Elastic Block Store. EBS volumes are network attached storage that can be attached to EC2 instances.
EBS volume data persists independently of the life of the instance. EBS volumes do not need to be attached to an instance. You can attach multiple EBS volumes to an instance. You cannot attach an EBS volume to multiple instances (use Elastic File Store instead).
EBS volume data is replicated across multiple servers in an AZ. EBS volumes must be in the same AZ as the instances they are attached to.
EBS is designed for an annual failure rate of 0.1%-0.2% & an SLA of
99.95%.
Termination protection is turned off by default and must be manually
enabled (keeps the volume/data when the instance is terminated).
Root EBS volumes are deleted on termination by default.
Extra non-boot volumes are not deleted on termination by default. The behavior can be changed by altering the “DeleteOnTermination” attribute.
You can now create AMIs with encrypted root/boot volumes as well as data volumes (you can also use separate CMKs per volume). Volume sizes and types can be upgraded without downtime (except for magnetic standard). Elastic Volumes allow you to increase volume size, adjust performance, or change the volume type while the volume is in use. To migrate volumes between AZ’s create a snapshot then create a volume in another AZ from the snapshot (possible to change size and type). Auto-enable IO setting prevents the stopping of IO to a disk when AWS detects inconsistencies.
The root device is created under /dev/sda1 or /dev/xvda. Magnetic EBS is for workloads that need throughput rather than IOPS. Throughput optimized EBS volumes cannot be a boot volume. Each instance that you launch has an associated root device volume, either an Amazon EBS volume or an instance store volume.
You can use block device mapping to specify additional EBS volumes or instance store volumes to attach to an instance when it’s launched. You can also attach additional EBS volumes to a running instance. You cannot decrease an EBS volume size.
When changing volumes, the new volume must be at least the size of the current volume’s snapshot. Images can be made public but not if they’re encrypted. AMIs can be shared with other accounts. You can have up to 5,000 EBS volumes by default. You can have up to 10,000 snapshots by default.
