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Re: Sudden Query slowdown on our Postgresql Server

From: Yeb Havinga <yebhavinga(at)gmail(dot)com>
To: Sebastian Melchior <webmaster(at)mailz(dot)de>
Cc: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Sudden Query slowdown on our Postgresql Server
Date: 2012-03-23 07:10:37
Message-ID: 4F6C21ED.903@gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 2012-03-23 05:53, Sebastian Melchior wrote:
> Hi,
>
> we already used iostat and iotop during times of the slowdown, there is no sudden drop in I/O workload in the times of the slowdown. Also the iowait does not spike and stays as before.
> So i do not think that this is I/O related. As the disks are SSDs there also still is some "head room" left.

I've seen a ssd completely lock up for a dozen seconds or so after 
giving it a smartctl command to trim a section of the disk. I'm not sure 
if that was the vertex 2 pro disk I was testing or the intel 710, but 
enough reason for us to not mount filesystems with -o discard.

regards,
Yeb




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