From: Roberto Spadim <rspadim@gmail.com>
To: struhlo@centrum.sk
Cc: Linux-RAID <linux-raid@vger.kernel.org>
Subject: Re: raid1 read io balancing algorithm
Date: Thu, 8 Aug 2013 11:27:37 -0300 [thread overview]
Message-ID: <CAH3kUhF+JwO6KX2sWE+psVbBugx3nGfTiB_-jAvoPCj2vr77dw@mail.gmail.com> (raw)
In-Reply-To: <20130808110452.464E2097@centrum.sk>
hi, from what i remember, it's done only with device "last position"
AKA "disk head position"
the device with head position near to position being read is "selected"
on sequencial reads, the last used device is used, considering that
for sequencial reads a single disk is faster, because we don't waste
3ms to positioning head to sector, that's near true if you don't have
diferent devices speed (7200rpm + 10000rpm + 15000rpm + ssd)
the best source of this information is source code of raid1.c
it's a function (i don't remember the name, but something like read_balancing)
sorry many emails the mail list denied HTML emails
prev parent reply other threads:[~2013-08-08 14:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-08 9:04 raid1 read io balancing algorithm struhlo
2013-08-08 14:26 ` Roberto Spadim
2013-08-08 14:27 ` Roberto Spadim [this message]
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