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From Ryan King <r...@twitter.com>
Subject Re: Can Cassandra make real use of several DataFileDirectories?
Date Mon, 26 Apr 2010 19:11:33 GMT
2010/4/26 Roland Hänel <roland@haenel.me>:
> Hm... I understand that RAID0 would help to create a bigger pool for
> compactions. However, it might impact read performance: if I have several
> CF's (with their SSTables), random read requests for the CF files that are
> on separate disks will behave nicely - however if it's RAID0 then a random
> read on any file will create a random read on all of the hard disks.
> Correct?

Without RAID0 you will end up with host spots (a compaction could end
up putting a large SSTable on one disk, while the others have smaller
SSTables). If you have many CFs this might average out, but it might
not and there are no guarantees here. I'd reccomend RAID0 unless you
have reason to do something else.

-ryan

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