From: Roman Mamedov <rm@romanrm.ru>
To: stan@hardwarefreak.com
Cc: tomas.hodek@volny.cz, linux-raid@vger.kernel.org
Subject: Re: raid1 read balance with write mostly
Date: Sun, 3 Feb 2013 04:07:58 +0600 [thread overview]
Message-ID: <20130203040758.5e2e7f3c@natsu> (raw)
In-Reply-To: <510D8A8C.5090505@hardwarefreak.com>
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On Sat, 02 Feb 2013 15:52:12 -0600
Stan Hoeppner <stan@hardwarefreak.com> wrote:
> So under heavy read load, in this case we'd probably want the slow 3TB drive
> to contribute to the workload.
No, it should behave as documented.
-W, --write-mostly
subsequent devices listed in a --build, --create, or --add com‐
mand will be flagged as 'write-mostly'. This is valid for RAID1
only and means that the 'md' driver will avoid reading from
these devices if at all possible.
if at all possible = if there is any other mirror still alive, do not read from
this one.
BTW I also run an SSD+HDD array, and after a brief testing today I did notice
some reads from the HDD on reading from the array showing up in iostat. So I
can confirm the bug.
--
With respect,
Roman
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next prev parent reply other threads:[~2013-02-02 22:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-02 17:38 raid1 read balance with write mostly tomas.hodek
2013-02-02 21:52 ` Stan Hoeppner
2013-02-02 22:07 ` Roman Mamedov [this message]
2013-02-02 22:16 ` Tommy Apel Hansen
2013-02-03 9:02 ` tomas.hodek
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