From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 42939] hv_storvsc - write cache enabled by default and cannot
be disabled
Date: Mon, 19 Mar 2012 19:33:30 GMT
Message-ID: <201203191933.q2JJXU7i027495@bugzilla.kernel.org>
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https://bugzilla.kernel.org/show_bug.cgi?id=42939
--- Comment #1 from Mark 2012-03-19 19:33:29 ---
Additional information:
trying to disable the writecache leads to the partition on the SCSI device
getting remounted read-only due to device errors.
Additional information (2):
I get 5.000 to 6.000 random reads per second even when manually creating the
fiometer file using random data from /dev/urandom (ie. fio doesn't access
zeroes in that case).
Additional information (3):
The host doesn't seem to cache anything: "dd iflag=direct if=/dev/sda bs=1M
of=/dev/null count=10" always and repeatedly gives me around 30-60 MB/s.
Additional information (4):
I did a simple MySQL InnoDB ACID transaction test where subsequent transactions
are done via a remote mysql client as fast as possible. I crashed the host
hardware and checked if all transactions reported as completed had been
committed to disk: no obvious problems there -- seemingly the reported
writecache has no writecache-effects at all...??
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