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From aaron morton <aa...@thelastpickle.com>
Subject Re: weird behavior with RAID 0 on EC2
Date Sun, 31 Mar 2013 10:03:03 GMT
> Ok, if you're going to look into it, please keep me/us posted.
It's not on my radar.

Cheers

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

@aaronmorton
http://www.thelastpickle.com

On 28/03/2013, at 2:43 PM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:

> Ok, if you're going to look into it, please keep me/us posted.
> 
> It happen twice for me, the same day, within a few hours on the same node and only happened
to 1 node out of 12, making this node almost unreachable.
> 
> 
> 2013/3/28 aaron morton <aaron@thelastpickle.com>
> 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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