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From Aaron McCurry <>
Subject Re: Ideal configuration for given hardware
Date Mon, 24 May 2010 19:27:36 GMT
Thanks, a lot!  So for RAID 10, is the thought that the node can survive a
single disk failure and keep going until a normal maintain cycle?  Also are
you saying that you would configure a single RAID 10 for the whole box?  OS
included?  I have 8 x 500 Gig drives, so that would leave me with 2T per
box, which I think is fine.  But I do have one question, in this
configuration would commit log writing and data directory
compaction interfere with one another?  Just based on what I read, it seems
as though you want at least disks/partitions, one for commit log and one for
data.  Thanks again for the feedback!


On Mon, May 24, 2010 at 3:12 PM, Ian Soboroff <> wrote:

> My data disks on two of my nodes are RAID-5, just because of
> circumstances.  My other nodes are JBOD.  I don't notice any real
> difference, but I haven't strongly benched it.
> Ian
> On Mon, May 24, 2010 at 2:45 PM, Jonathan Ellis <> wrote:
>> I can think of at least 2 clusters running 32GB boxes with single
>> Cassandra processes on each.  (16 seems to be more common.)  At 64 I
>> would seriously consider multiple processes per machine.  You'd want
>> to configure a Snitch such that same-machine boxes were considered the
>> same rack, there is no separate closeness level of same machine.
>> At 32 I think you're fine with one process.  Watch for latency spikes
>> and see how it goes.
>> I would run raid 10 on the data disks if you can afford giving up the
>> space, otherwise raid0.  I don't know that anyone's tested raid5.
>> On Sun, May 23, 2010 at 3:30 PM, Aaron McCurry <>
>> wrote:
>> > I am planning on setting up a Cassandra cluster on a small 16 node
>> cluster
>> > (possibly 32 way).  Each machine has 8 cores 32 Gig of ram and 8 hds.
>>  My
>> > first thought is to setup one of those hds for the commit log, 6 for
>> data
>> > and leave one for the OS.  However I do have a concern about best
>> utilizing
>> > my memory, should I run a larger heap?  Should I run several cassandra
>> > processes on the same box?
>> > My concern about the larger heap is because GC's typically get slower.
>>  And
>> > if I run several procs, does cassandra realize that it's the same box
>> for
>> > replication purposes?
>> > I do have other hd conf options, hardware RAID 0,1,or 5.
>> > Just looking for some general configuration options as well as some real
>> > world successes with similarly sized hardware.  Thanks!
>> > Aaron
>> --
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of Riptano, the source for professional Cassandra support

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