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I read the Alibaba Cloud documentation referenced here. Alibaba implements Triplicate Technology for maintaining data. Also here they mentioned that

When the maximum number of automatic snapshots has been reached, the oldest automatic snapshot will be deleted.

I didn't really understand as Triplicate Technology doesn't allow the snapshots to delete which are referenced.But as per the quote, Snapshots deletes the oldest snapshot once the maximum number of snapshots is reached.

Since The initial snapshot is referrenced by all snapshots, will it be deleted?

John Hanley
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Sai Sarath C P
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1 Answers1

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The answer is yes, the oldest snapshot will be deleted.

Note: Triplicate Technology is not really related to snapshots. It is technology that maintains "state" for replicating data in three locations. This could equally apply to to disk storage, OSS as well as snapshots.

Below is an Alibaba article that describes what happens when an older snapshot is deleted and a newer snapshot depend on the older snapshot.

Basically data held in the snapshot being deleted is copied to the next newer snapshot.

In reality, no data is actually copied. There are reference pointers to multiple-time-versions of a data block. The pointers get updated and the reference counters are changed. Once a data block is no longer referenced by any snapshots its snapshot storage space is released.

Incremental snapshot mechanism

John Hanley
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