From: Andre Noll <maan@tuebingen.mpg.de>
To: Dave Chinner <david@fromorbit.com>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>,
linux-raid@vger.kernel.org, linux-nfs@vger.kernel.org,
linux-block@vger.kernel.org, linux-xfs@vger.kernel.org,
it+linux-raid@molgen.mpg.de
Subject: Re: How to debug intermittent increasing md/inflight but no disk activity?
Date: Thu, 11 Jul 2024 13:23:12 +0200 [thread overview]
Message-ID: <Zo_AoEPrCl0SfK1Z@tuebingen.mpg.de> (raw)
In-Reply-To: <Zo8VXAy5jTavSIO8@dread.disaster.area>
On Thu, Jul 11, 09:12, Dave Chinner wrote
> > Of course it’s not reproducible, but any insight how to debug this next time
> > is much welcomed.
>
> Probably not a lot you can do short of reconfiguring your RAID6
> storage devices to handle small IOs better. However, in general,
> RAID6 /always sucks/ for small IOs, and the only way to fix this
> problem is to use high performance SSDs to give you a massive excess
> of write bandwidth to burn on write amplification....
FWIW, our approach to mitigate the write amplification suckage of large
HDD-backed raid6 arrays for small I/Os is to set up a bcache device
by combining such arrays with two small SSDs (configured as raid1).
Best
Andre
--
Max Planck Institute for Biology
Tel: (+49) 7071 601 829
Max-Planck-Ring 5, 72076 Tübingen, Germany
http://people.tuebingen.mpg.de/maan/
next prev parent reply other threads:[~2024-07-11 11:47 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-10 11:46 How to debug intermittent increasing md/inflight but no disk activity? Paul Menzel
2024-07-10 11:54 ` Roger Heflin
2024-07-23 10:33 ` Paul Menzel
2024-07-10 23:12 ` Dave Chinner
2024-07-11 8:51 ` Johannes Truschnigg
2024-07-11 11:23 ` Andre Noll [this message]
2024-07-11 22:26 ` Dave Chinner
2024-07-13 15:47 ` Andre Noll
2024-07-23 15:13 ` Paul Menzel
2024-07-12 3:54 ` Dragan Milivojević
2024-07-12 23:45 ` Dave Chinner
2024-07-13 17:44 ` Dragan Milivojević
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