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From Paul Pollack <>
Subject Re: Drastic increase in disk usage after starting repair on 3.7
Date Thu, 21 Sep 2017 11:58:11 GMT
Thanks for the suggestions guys.

Nicolas, I just checked nodetool listsnapshots and it doesn't seem like
those are causing the increase:

Snapshot Details:
Snapshot name                            Keyspace name Column family
name         True size Size on disk
1479343904106-statistic_segment_timeline klaviyo
statistic_segment_timeline 91.73 MiB 91.73 MiB
1479343904516-statistic_segment_timeline klaviyo
statistic_segment_timeline 69.42 MiB 69.42 MiB
1479343904607-statistic_segment_timeline klaviyo
statistic_segment_timeline 69.43 MiB 69.43 MiB

Total TrueDiskSpaceUsed: 91.77 MiB

Kurt, we definitely do have a large backlog of compactions, but I would
expect only the currently running compactions to take up 2x extra space,
and for that space to be freed up after its completion, is that an
inaccurate idea of how compaction actually works? When the disk was almost
full at 2TB I increased the EBS volume to 3TB, and now it's using 2.6TB so
I think it's only a matter of hours before it takes up the space on the
rest of the volume. The largest files on disk are *-big-Data.db files. Is
there anything else I can check that might indicate whether or not the
repair is really the root cause of this issue?


On Thu, Sep 21, 2017 at 4:02 AM, Nicolas Guyomar <>

> Hi Paul,
> This might be a long shot, but some repairs might fail to clear their
> snapshot (not sure if its still the case with C* 3.7 however, I had the
> problem on 2.X branche).
> What does nodetool listsnapshot indicate ?
> On 21 September 2017 at 05:49, kurt greaves <> wrote:
>> repair does overstream by design, so if that node is inconsistent you'd
>> expect a bit of an increase. if you've got a backlog of compactions that's
>> probably due to repair and likely the cause of the increase. if you're
>> really worried you can rolling restart to stop the repair, otherwise maybe
>> try increasing compaction throughput.

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