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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Cassandra 1.0.0 - Node Load Bug
Date Thu, 20 Oct 2011 17:58:01 GMT
On Thu, Oct 20, 2011 at 12:53 PM, Dan Hendry <dan.hendry.junk@gmail.com>wrote:

> I have been playing around with Cassandra 1.0.0 in our test environment it
> seems pretty sweet so far. I have however come across what appears to be a
> bug tracking node load. I have enabled compression and levelled compaction
> on all CFs (scrub  + snapshot deletion) and the nodes have been operating
> normally for a day or two. I started getting concerned when the load as
> reported by nodetool ring kept increasing (it seems monotonically) despite
> seeing a compression ratio of ~2.5x (as a side note, I find it strange
> Cassandra does not provide the compression ratio via jmx or in the logs). I
> initially thought there might be a bug in cleaning up obsolete SSTables but
> I then noticed the following discrepancy:
>
>
>
> Nodetool ring reports:
>
>                 10.112.27.65    datacenter1 rack1       Up     Normal  8.64
> GB         50.00%  170141183460469231731687303715884105727
>
>
>
> Yet du . –h reports: only 2.4G in the data directory.
>
>
>
> After restarting the node, nodetool ring reports a more accurate:
>
> 10.112.27.65    datacenter1 rack1       Up     Normal  2.35 GB
> 50.00%  170141183460469231731687303715884105727
>
>
>
> Again, both compression and levelled compaction have been enabled on all
> CFs. Is this a known issue or has anybody else observed a similar pattern?
>
>
>
> Dan Hendry
>
> (403) 660-2297
>
>
>


In 0.7.8 known bug. Scrub would 'orphan' files that way and the counts would
be off like this. If you restart the node and the counts like equal again it
might be some type of regression.

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