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From Ramzi Rabah <rra...@playdom.com>
Subject Re: Removes increasing disk space usage in Cassandra?
Date Fri, 04 Dec 2009 19:55:37 GMT
Just to be clear what I meant is that I ran the deletions and
compaction with GCGraceSeconds set to 1 hour, so there was enough time
for the tombstones to expire.
Anyway I will try to make a simpler test case to hopefully reproduce
this, and I will share the code if I can reproduce.

Ray

On Fri, Dec 4, 2009 at 11:04 AM, Ramzi Rabah <rrabah@playdom.com> wrote:
> Hi Jonathan I have changed that to 3600(one hour) based on your
> recommendation before.
>
> On Fri, Dec 4, 2009 at 11:01 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
>> 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.
>>  -->
>>  <GCGraceSeconds>864000</GCGraceSeconds>
>>
>> On Fri, Dec 4, 2009 at 12:51 PM, Ramzi Rabah <rrabah@playdom.com> 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 <jbellis@gmail.com> 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 <rrabah@playdom.com> 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 <rrabah@playdom.com>
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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