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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Can Cassandra make real use of several DataFileDirectories?
Date Mon, 26 Apr 2010 18:10:55 GMT
http://wiki.apache.org/cassandra/CassandraHardware

On Mon, Apr 26, 2010 at 1:06 PM, Edmond Lau <edmond@ooyala.com> wrote:
> Ryan -
>
> You (or maybe someone else) mentioned using RAID-0 instead of multiple
> data directories at the Cassandra hackathon as well.  Could you
> explain the motivation behind that?
>
> Thanks,
> Edmond
>
> On Mon, Apr 26, 2010 at 9:53 AM, Ryan King <ryan@twitter.com> wrote:
>> I would recommend using RAID-0 rather that multiple data directories.
>>
>> -ryan
>>
>> 2010/4/26 Roland Hänel <roland@haenel.me>:
>>> I have a configuration like this:
>>>
>>>   <DataFileDirectories>
>>>       <DataFileDirectory>/storage01/cassandra/data</DataFileDirectory>
>>>       <DataFileDirectory>/storage02/cassandra/data</DataFileDirectory>
>>>       <DataFileDirectory>/storage03/cassandra/data</DataFileDirectory>
>>>   </DataFileDirectories>
>>>
>>> After loading a big chunk of data into cassandra, I end up wich some 70GB in
>>> the first directory, and only about 10GB in the second and third one. All
>>> rows are quite small, so it's not just some big rows that contain the
>>> majority of data.
>>>
>>> Does Cassandra have the ability to 'see' the maximum available space in
>>> these directory? I'm asking myself this question since my limit is 100GB,
>>> and the first directory is approaching this limit...
>>>
>>> And, wouldn't it be better if Cassandra tried to 'load-balance' the files
>>> inside the directories because this will result in better (read) performance
>>> if the directories are on different disks (which is the case for me)?
>>>
>>> Any help is appreciated.
>>>
>>> Roland
>>>
>>>
>>
>

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