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From Jonathan Ellis <>
Subject Re: Removes increasing disk space usage in Cassandra?
Date Fri, 04 Dec 2009 19:01:59 GMT
this is what I was referring to by "the period specified in your config file":

   ~ Time to wait before garbage-collection deletion markers.  Set this to
   ~ a large enough value that you are confident that the deletion marker
   ~ will be propagated to all replicas by the time this many seconds has
   ~ elapsed, even in the face of hardware failures.  The default value is
   ~ ten days.

On Fri, Dec 4, 2009 at 12:51 PM, Ramzi Rabah <> wrote:
> I think there might be a bug in the deletion logic. I removed all the
> data on the cluster by running remove on every single key I entered,
> and I run major compaction
> nodeprobe -host hostname compact on a certain node, and after the
> compaction is over, I am left with one data file/ one index file and
> the bloom filter file,
> and they are the same size of data as before I started doing the deletes.
> On Thu, Dec 3, 2009 at 6:09 PM, Jonathan Ellis <> wrote:
>> cassandra never modifies data in-place.  so it writes tombstones to
>> supress the older writes, and when compaction occurs the data and
>> tombstones get GC'd (after the period specified in your config file).
>> On Thu, Dec 3, 2009 at 8:07 PM, Ramzi Rabah <> wrote:
>>> Looking at jconsole I see a high number of writes when I do removes,
>>> so I am guessing these are tombstones being written? If that's the
>>> case, is the data being removed and replaced by tombstones? and will
>>> they all be deleted eventually when compaction runs?
>>> On Thu, Dec 3, 2009 at 3:18 PM, Ramzi Rabah <> wrote:
>>>> Hi all,
>>>> I ran a test where I inserted about 1.2 Gigabytes worth of data into
>>>> each node of a 4 node cluster.
>>>> I ran a script that first calls a get on each column inserted followed
>>>> by a remove. Since I was basically removing every entry
>>>> I inserted before, I expected that the disk space occupied by the
>>>> nodes will go down and eventually become 0. The disk space
>>>> actually goes up when I do the bulk removes to about 1.8 gigs per
>>>> node. Am I missing something here?
>>>> Thanks a lot for your help
>>>> Ray

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