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Zlatan
Zlatan

Reputation: 31

How EBS snapshots are stored in S3? EBS = Block store, S3 = Object store

I get the whole point that EBS snapshots are stored on S3 and they are not visible through the console. But how EBS snapshots are stored on S3? Since S3 is and object based store? Does the snapshot stays on S3 similar to a DB dump file? And EBS snapshots are incremental. And does S3 add all the incremental snapshots and store them as a one snapshot on S3 ?

Upvotes: 1

Views: 123

Answers (1)

jarmod
jarmod

Reputation: 78860

EBS snapshots are block-based. If a given block is 'dirty' then a snapshot of that block is taken and stored to S3. That's the 'incremental' part of the process - only those blocks that have changed get copied.

At a higher-level, a specific snapshot of an EBS volume is just an ordered list of pointers to blocks that comprise the original EBS volume at the time of the snapshot. A background process reaps blocks that are no longer referenced.

This information was derived from details of an old EC2/EBS service outage.

Upvotes: 2

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