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From Mike Yeap <wkk1...@gmail.com>
Subject Re: [Marketing Mail] Cassandra 2.1: Snapshot data changing while transferring
Date Tue, 31 May 2016 15:11:41 GMT
Hi Paul, what is the value of the snapshot_before_compaction property in
your cassandra.yaml?

Say if another snapshot is being taken (because compaction kicked in and
snapshot_before_compaction property is set to TRUE) and at this moment
you're tarring the snapshot folders......

Maybe can take a look at the records in system.compaction:

select * from system.compaction_history;


Regards,
Mike Yeap



On Tue, May 31, 2016 at 5:21 PM, Paul Dunkler <paul@uplex.de> wrote:

> And - as an addition:
>
> Shoudln't that be documented that even snapshot files can change?
>
> I guess this might come from the incremental repairs...
>
> The repair time is stored in the sstable (RepairedAt timestamp metadata).
>
>
> ok, that sounds interesting.
> Could that also happen to incremental backup files as well? I had another
> case where incremental backup files were totally deleted automagically.
>
> And - what is the suggested way to solve that problem? Should i try again
> tar-ing the snapshot until it doesn't happen anymore that something changes
> in between?
> Or is there a way to "pause" the incremental repairs?
>
>
> Cheers,
> Reynald
>
> On 31/05/2016 11:03, Paul Dunkler wrote:
>
> Hi there,
>
> i am sometimes running in very strange errors while backing up snapshots
> from a cassandra cluster.
>
> Cassandra version:
> 2.1.11
>
> What i basically do:
> 1. nodetool snapshot
> 2. tar all snapshot folders into one file
> 3. transfer them to another server
>
> What happens is that tar just sometimes give the error message "file
> changed as we read it" while its adding a .db-file from the folder of the
> previously created snapshot.
> If i understand everything correct, this SHOULD never happen. Snapshots
> should be totally immutable, right?
>
> Am i maybe hitting a bug or is there some rare case with running repair
> operations or what-so-ever which can change snapshotted data?
> I already searched through cassandra jira but couldn't find a bug which
> looks related to this behaviour.
>
> Would love to get some help on this.
>
> —
> Paul Dunkler
>
>
>
> —
> Paul Dunkler
>
> ** * * UPLEX - Nils Goroll Systemoptimierung
>
> Scheffelstraße 32
> 22301 Hamburg
>
> tel +49 40 288 057 31
> mob +49 151 252 228 42
> fax +49 40 429 497 53
>
> xmpp://pauldunkler@jabber.ccc.de
>
> http://uplex.de/
>
>
> —
> Paul Dunkler
>
> ** * * UPLEX - Nils Goroll Systemoptimierung
>
> Scheffelstraße 32
> 22301 Hamburg
>
> tel +49 40 288 057 31
> mob +49 151 252 228 42
> fax +49 40 429 497 53
>
> xmpp://pauldunkler@jabber.ccc.de
>
> http://uplex.de/
>
>

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