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From Wayne <wav...@gmail.com>
Subject Re: Node OOM Problems
Date Tue, 24 Aug 2010 06:55:08 GMT
Thanks for the confirmation this is NOT the way to go. I will stick with 4
disks raid 0 with a single data directory.


On Mon, Aug 23, 2010 at 9:24 PM, Rob Coli <rcoli@digg.com> wrote:

> On 8/22/10 12:00 AM, Wayne wrote:
>
>> Due to compaction being so expensive in terms of disk resources, does it
>> make more sense to have 2 data volumes instead of one? We have 4 data
>> disks in raid 0, would this make more sense to be 2 x 2 disks in raid 0?
>> That way the reader and writer I assume would always be a different set
>> of spindles?
>>
>
> Cassandra supports multiple data directories via specifying multiple
> DataFileDirectory items in the DataFileDirectories block. Unfortunately due
> to the way that compaction currently works, this often results in one or the
> other drive being much hotter than the other and lots of inter-disk
> shuffling of data.
>
> https://issues.apache.org/jira/browse/CASSANDRA-897
>
> Is a JIRA which refers to these issues. I am not aware of anyone who has
> successfully improved their overall performance via multiple data
> directories. I am, however, aware of people who have encountered negative
> consequences as a result of doing so. As such, I do not recommend it.
>
> =Rob
>
>

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