IT 4100 : File Systems and Storage Technologies

Cloud - EBS

Cloud Storage - EBS

• Overview
• elastic block store
• provides persistent block storage volumes for EC2
  • independent of ec2 instance
• replicated within AZ

Cloud Storage - EBS

Block vs object storage: If you want to change 1 char of a 1GB file, for object you have to re-update the entire file. With block storage we only update the block that contains the char.

Block storage are typically faster and use less bandwidth, but can cost more.

Cloud Storage - EBS

• Can make backups to S3
• Can choose from SSD or HDD
  • ssd
  • general purpose: most workloads, virtual desktops, low-latency apps, boot volume
  • provisioned iops: critical apps requiring higher iops, large db workloads
  • hdd
  • throughput optimized: streaming workloads requiring low price, big data, data warehouse,
  • cold: lowest cost storage, throughput-oriented storage for large volumes of data that are infrequently accessed

Cloud Storage - EBS

• Can take point-in-time snapshots of volume (store in s3)
• Only can be mounted to an instance in same AZ

Cloud Storage - IOPS vs throughput

• IOPS measures the number of read/write ops per second
• Throughput is the number of bits read or written per second (usually measures in MB/s)

Cloud Storage - analogy

• You have 4 buckets (Disk blocks) of the same size that you want to fill or empty water.
• You’ll be using a jug to transfer the water into the buckets. Now your question will be :
  • At a given time (per second), how many jugs of water can you pour(write) or withdraw (read)? This is IOPS
  • At a given time (per second) what’s the amount(bit, kb, mb, ect) of water the jug can transfer into/out of the bucket continuously? This is throughput.
• Additionally, there is a delay in the process of you pouring and or withdrawing the water. This is Latency.

Cloud Storage - EBS - Snapshots

• They are incremental
  • only the blocks that have changed after your most recent snapshot are saved