Amazon EBS Vs S3 – Some Comparisons
Versus
Have any of you IT folks out there ever wondered how Amazon Elastic Block Storage (EBS), a new type of storage designed specifically for EC2 instances, measures up to Amazon S3 on the elastic cloud? Here are some key differences in cloud performance that I ran across in a recent article:
- For a 20 Gigabyte volume, Amazon estimates an annual failure range for EBS volumes from 1-in-200 to 1-in-1000, increasing as the volume rises. So, that means, you should keep a current snapshot on S3, or back-up the contents elsewhere and get to it so that you can restore quickly.
- EBS accounts can have a maximum of 20 volumes unless Amazon requests a higher limit. The maximum size of a volume is 1 TB, and the storage on a volume is limited to the provisioned size. It cannot be changed. EBS volumes can only be accessed from an EC2 instance in the same availability zone. Meanwhile, snapshots on S3 can be accessed from any availability zone.
- While S3 is subject to “eventual consistency” (delays in writes appearing in the system), EBS has no delays. Also EBS can only be accessed by one machine at a time, while S3 snapshots can be shared.
- Where performance is concerned, S3 has the higher latency and also has higher variation in latency. In addition, S3 write latency can also be more frequent than read latency. EBS, on the other hand, has lower latency with less variation. It also has writeback caching for very low-write latency.
- Throughput: S3 has maximum throughput (single threaded ) of approximately 20 MB/s (or 25 MB/s for multithreaded). This is on a small scale. Throughput rises to 50 MB/s on the large and extra-large instances. In comparison, EBS has a maximum throughput limited only by the network, This is approximately 25 MB/s on a small instance and 50 MB/s on large instances, and 100 MB/s on extra-large instances. Yet, as both S3 and EBS are shared resources, they are subject to slowdown under heavy traffic.
- For file listing, S3 is slow and search is by prefix only, whereas EBS has fast directory listing and searching.
See also Monitis S3 Monitoring Debuts