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From Edmond Lau <>
Subject Re: Can Cassandra make real use of several DataFileDirectories?
Date Mon, 26 Apr 2010 18:06:37 GMT
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?


On Mon, Apr 26, 2010 at 9:53 AM, Ryan King <> wrote:
> I would recommend using RAID-0 rather that multiple data directories.
> -ryan
> 2010/4/26 Roland Hänel <>:
>> 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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