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From: Carsten Aulbert <Carsten.Aulbert@aei.mpg.de>
To: Stan Hoeppner <stan@hardwarefreak.com>
Cc: xfs@oss.sgi.com
Subject: Re: extremely slow file creation/deletion after xfs ran full
Date: Wed, 14 Jan 2015 07:07:00 +0100	[thread overview]
Message-ID: <54B60784.5090505@aei.mpg.de> (raw)
In-Reply-To: <54B58367.1070008@hardwarefreak.com>

Hi Stan

On 01/13/2015 09:43 PM, Stan Hoeppner wrote:
> With your file sizes that seems a recipe for hotspots.  What do the
> controller metrics tell you about IOs per drive, bytes per drive?  Are
> they balanced?
> 

They looked ok from 10000ft, but unfortunately, the controller is not
that talkative :(

>> After the arrival of "advanced format" HDD and SSDs we usually try to
>> align everything to full 1 MByte or larger, just to be sure any
>> combination of 512b, 4kb, ... will eventually align :)
> 
> It's not that simple with striping.  Partitions need to start and end on
> stripe boundaries, not simply multiples of 4KB or 1MB as with single
> disks. If you use non power of 2 drive counts in a stripe, aligning at
> multiples of 1MB will screw ya, e.g. 12 drives * 64KB is a 768KB stripe.

At the moment there are 16 disks (or 8 "data" disks), so here, power of
2 still prevails. But still, very valid remark!

Cheers

Carsten

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  reply	other threads:[~2015-01-14  6:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-12  8:36 extremely slow file creation/deletion after xfs ran full Carsten Aulbert
2015-01-12 12:44 ` Brian Foster
2015-01-12 13:30 ` Carsten Aulbert
2015-01-12 15:52   ` Brian Foster
2015-01-12 16:09     ` Carsten Aulbert
2015-01-12 16:37       ` Brian Foster
2015-01-12 17:33         ` Carsten Aulbert
2015-01-13 20:06           ` Stan Hoeppner
2015-01-13 20:13             ` Carsten Aulbert
2015-01-13 20:43               ` Stan Hoeppner
2015-01-14  6:07                 ` Carsten Aulbert [this message]
2015-01-13 20:33           ` Dave Chinner
2015-01-14  6:12             ` Carsten Aulbert
2015-01-16 15:35               ` Carlos Maiolino

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