What is Elastic Block Store and What we should know about?

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What is Block Store ? — Concept of cloud hosted data persistence (such as physical hard drive, form of network-attached-storage[NAS]).

1. Storage in such is organized as blocks (physical record, is sequence of bytes,bits).
2. This Behavior are seen in Traditional disk or tape storage.(Blocks are identified by which they may be stored and retrieved).

Example : Amazon Elastic Block Store (EBS) — Which offers replication of reliability or backup services.

Amazon EBS : — provides block level storage volumes as a service that works in conjunction with EC2 Instance (were more number of volumes can be attached to ec2 instance in the same availability region).

1. Unlike EC2 Instances which stores are ephemeral or lose any data when they terminated but EBS volumes maintains their state when stopped or detached from an instance.(Persist independently from the life of instance).

Features of Amazon EBS :

1. EBS volumes are created in a specific availability zone (can be attached to any instance in same availability zone) —“ To make available outside of availability zone — were we can create snapshot and restore the snapshot to a new volume anywhere in the region”.
2. Volume Types : Offer 2 Types SSD (transactional workloads)& HDD (large streaming workloads)

• General Purpose SSD (gp2) — offers base performance of 3 IOPS/GiB , with ability to burst to 3000IOPS for extended period of time. These volumes are ideal for broad ranges such as test,boot and development volumes.
• Provisioned IOPS SSD (io1) — volume supports to 64,000 IOPS and 1000 MiB/s of throughput.This allows you to predictably scale to ten of thousand of IOPS per EC2 Instance.
• Throughput Optimized HDD (st1) — Provides low cost magnetic storage defines performance in terms of throughput rather than IOPS. These volumes are ideal for large ,sequential workloads.
• Cold HDD (sc1) — Same as Throughput Optimized HDD — Infrequent access of date this kind of HDD can be used.

3. Benefits of EBS Volumes :

• Data availability — when we create an EBS volume in an availability zone,it is automatically replicated in same zone to Prevent data loss due to failure of any hardware component.
• Data Persistence — off-instance storage that can persist independently from the life of an instance.By default , root EBS volumes that created and attached to instance is deleted when the instance in terminated.
• Data Encryption — we can create EBS volumes with encryption feature to EBS volumes to meet a wide range of data-at-rest encryption requirements for regulated/audited data and applications.
• Snapshots — Amazon EBS provides the ability to create snapshots (backups) of any EBS volume and write a copy of the data in the volume to Amazon S3, where it is stored redundantly in multiple Availability Zones.
• Flexibility — EBS volumes support live configuration changes while in production. You can modify volume type, volume size, and IOPS capacity without service interruptions.

EBS Performance : I/O Characteristics and Monitoring

1. IOPS : IOPS are unit of measure representing i/o operations per second.(Operations measured in KiB).The maximum amount of data that a volume type counts as a single I/O. I/O size is capped at 256 KiB for SSD volumes and 1,024 KiB for HDD volumes because SSD volumes handle small or random I/O much more efficiently than HDD volumes.
2. Volume Queue Length and Latency : — Number of Pending I/O requests for a device.Latency is the true end-to-end client time of an I/O operation, in other words, the time elapsed between sending an I/O to EBS and receiving an acknowledgement from EBS that the I/O read or write is complete. Queue length must be correctly calibrated with I/O size and latency to avoid creating bottlenecks either on the guest operating system or on the network link to EBS.

Monitor I/O Characteristics with CloudWatch :

1. BurstBalance — displays the burst bucket balance for gp2, st1, and sc1 volumes as a percentage of the remaining balance. When your burst bucket is depleted, volume I/O (for gp2 volumes) or volume throughput (for st1 and sc1 volumes) is throttled to the baseline
2. VolumeReadBytes/VolumeWriteBytes— Provides information on the read/write operations in a specified period of time. (Units: Bytes)
3. VolumeReadOps /VoumeWriteOps— The total number of read/write operations in a specified period of time.(Units: Count)
4. VoulmeTotalReadTime/VoulmeTotalWriteTime — The total number of seconds spent by all read/write operations that completed in a specified period of time.(Unit : Seconds)
5. VolumeIdleTime- The total number of seconds in a specified period of time when no read or write operations were submitted.(Units: Seconds)
6. VolumeQueueLength — The number of read and write operation requests waiting to be completed in a specified period of time.(Units: Count)
7. VolumeThroughputPercentage - Used with Provisioned IOPS SSD volumes only. The percentage of I/O operations per second (IOPS) delivered of the total IOPS provisioned for an Amazon EBS volume.(Units: Percent)
8. VolumeConsumedReadWriteOps — Used with Provisioned IOPS SSD volumes only. The total amount of read and write operations (normalized to 256K capacity units) consumed in a specified period of time.(Units: Count)

These are Basics things to know about EBS.

Thanks for Reading!.

Resources:

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AmazonEBS.html

https://www.datadoghq.com/blog/amazon-ebs-monitoring/