From: Eric Sandeen <sandeen@sandeen.net>
To: Helmut Tessarek <tessarek@evermeet.cx>,
Stan Hoeppner <stan@hardwarefreak.com>,
xfs@oss.sgi.com
Subject: Re: How to format RAID1 correctly
Date: Wed, 24 Sep 2014 11:18:18 -0500 [thread overview]
Message-ID: <5422EECA.10301@sandeen.net> (raw)
In-Reply-To: <5422E912.1000708@evermeet.cx>
On 9/24/14 10:53 AM, Helmut Tessarek wrote:
> On 2014-09-24 0:09, Stan Hoeppner wrote:
>> If you create any striped arrays, especially parity arrays, with md make
>> sure to manually specify chunk size and match it to your workload. The
>> current default is 512KB. This is too large for a great many workloads,
>> specifically those that are metadata heavy or manipulate many small
>> files. 512KB wastes space and with parity arrays causes RMW, hammering
>> throughput and increasing latency.
>
> Thanks again for the valueable information.
>
> I used to work with databases on storage subsystems, so placing GBs of
> database containers for tableapaces on arrays with a larger stripe size
> was actually beneficial.
> For log files and other data I usually used different cache settings and
> strip sizes.
>
> So how does this work with SW RAID?
>
> Does the XFS chunk size equal the amount of data touched by a single r/w
> operation?
It has more to do with where allocations start, so that allocations
don't cross stripe boundaries if possible.
-Eric
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next prev parent reply other threads:[~2014-09-24 16:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-24 0:46 How to format RAID1 correctly Helmut Tessarek
2014-09-24 2:05 ` Helmut Tessarek
2014-09-24 2:07 ` Eric Sandeen
2014-09-24 2:11 ` Helmut Tessarek
2014-09-24 2:21 ` Eric Sandeen
2014-09-24 2:30 ` Helmut Tessarek
2014-09-24 3:05 ` stan hoeppner
2014-09-24 3:15 ` Helmut Tessarek
2014-09-24 4:09 ` Stan Hoeppner
2014-09-24 15:53 ` Helmut Tessarek
2014-09-24 16:18 ` Eric Sandeen [this message]
2014-09-24 19:06 ` Stan Hoeppner
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