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From aaron morton <aa...@thelastpickle.com>
Subject Re: weird behavior with RAID 0 on EC2
Date Thu, 28 Mar 2013 02:26:40 GMT
I noticed this on an m1.xlarge (cassandra 1.1.10) instance today as well, 1 or 2 disks in a
raid 0 running at 85 to 100% the others 35 to 50ish. 

Have not looked into it. 

Cheers

-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 26/03/2013, at 11:57 PM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:

> We use C* on m1.xLarge AWS EC2 servers, with 4 disks xvdb, xvdc, xvdd, xvde parts of
a logical Raid0 (md0).
> 
> I use to see their use increasing in the same way. This morning there was a normal minor
compaction followed by messages dropped on one node (out of 12).
> 
> Looking closely at this node I saw the following:
> 
> http://img69.imageshack.us/img69/9425/opscenterweirddisk.png
> 
> On this node, one of the four disks (xvdd) started working hardly while other worked
less intensively.
> 
> This is quite weird since I always saw this 4 disks being used the exact same way at
every moment (as you can see on 5 other nodes or when the node ".239" come back to normal).
> 
> Any idea on what happened and on how it can be avoided ?
> 
> Alain


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