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From Ben Chobot <>
Subject Re: lots of extra bytes on disk
Date Thu, 28 Mar 2013 18:31:12 GMT
Sorry to make it confusing. I didn't have snapshots on some nodes; I just made a snapshot on
a node with this problem. 

So to be clear, on this one example node....
 Cassandra reports ~250GB of space used
 In a CF data directory (before snapshots existed), du -sh showed ~550GB
 After the snapshot, du in the same directory still showed ~550GB (they're hard links, so
that's correct)
 du in the snapshot directory for that CF shows ~250GB, and ls shows ~50 fewer files.

On Mar 28, 2013, at 11:10 AM, Hiller, Dean wrote:

> I am confused.  I thought you said you don't have a snapshot.  Df/du
> reports space used by existing data AND the snapshot.  Cassandra only
> reports on space used by actual data........if you move the snapshots, does
> df/du match what cassandra says?
> Dean
> On 3/28/13 12:05 PM, "Ben Chobot" <> wrote:
>> .....though interestingly, the snapshot of these CFs have the "right"
>> amount of data in them (i.e. it agrees with the live SSTable size
>> reported by cassandra). Is it total insanity to remove the files from the
>> data directory not included in the snapshot, so long as they were created
>> before the snapshot?
>> On Mar 28, 2013, at 10:54 AM, Hiller, Dean wrote:
>>> Have you cleaned up your snapshotsÅ those take extra space and don't just
>>> go away unless you delete them.
>>> Dean
>>> On 3/28/13 11:46 AM, "Ben Chobot" <> wrote:
>>>> Are you also running 1.1.5? I'm wondering (ok hoping) that this might
>>>> be
>>>> fixed if I upgrade.
>>>> On Mar 28, 2013, at 8:53 AM, Lanny Ripple wrote:
>>>>> We occasionally (twice now on a 40 node cluster over the last 6-8
>>>>> months) see this.  My best guess is that Cassandra can fail to mark an
>>>>> SSTable for cleanup somehow.  Forced GC's or reboots don't clear them
>>>>> out.  We disable thrift and gossip; drain; snapshot; shutdown; clear
>>>>> data/Keyspace/Table/*.db and restore (hard-linking back into place to
>>>>> avoid data transfer) from the just created snapshot; restart.
>>>>> On Mar 28, 2013, at 10:12 AM, Ben Chobot <>
>>>>> wrote:
>>>>>> Some of my cassandra nodes in my 1.1.5 cluster show a large
>>>>>> discrepancy between what cassandra says the SSTables should sum up
>>>>>> to,
>>>>>> and what df and du claim exist. During repairs, this is almost always
>>>>>> pretty bad, but post-repair compactions tend to bring those numbers
>>>>>> to
>>>>>> within a few percent of each other... usually. Sometimes they remain
>>>>>> much further apart after compactions have finished - for instance,
>>>>>> I'm
>>>>>> looking at one node now that claims to have 205GB of SSTables, but
>>>>>> actually has 450GB of files living in that CF's data directory. No
>>>>>> pending compactions, and the most recent compaction for this CF
>>>>>> finished just a few hours ago.
>>>>>> nodetool cleanup has no effect.
>>>>>> What could be causing these extra bytes, and how to get them to go
>>>>>> away? I'm ok with a few extra GB of unexplained data, but an extra
>>>>>> 245GB (more than all the data this node is supposed to have!) is
>>>>>> little extreme.

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