From: Jens Axboe <jaxboe@fusionio.com>
To: Spelic <spelic@shiftmail.org>
Cc: fio@vger.kernel.org
Subject: Re: Again on IOPS higher than expected in randwrite 4k
Date: Mon, 3 Jan 2011 12:05:33 +0100 [thread overview]
Message-ID: <4D21AD7D.7090707@fusionio.com> (raw)
In-Reply-To: <4D1FFB1B.1010000@shiftmail.org>
On 2011-01-02 05:12, Spelic wrote:
> Hello, I just subscribed, I noticed that some 20 days ago there was a
> thread on "IOPS higher than expected on randwrite, direct=1 tests" on
> this ML. It's curious because I subscribed to report basically the
> same thing.
>
> With Hitachi 7k1000 HDS721010KLA330 (maybe the same drives as
> Sebastian) I am seeing the same problem of IOPS too high with FIO, up
> to 300 IOPS per disk (up to 500 per disk with storsave=performance on
> my 3ware but that's probably cheating). I am doing 4k random writes.
>
> I followed the discussion, I don't really agree with the point at the
> end of the discussion, so I'd like to bump this thread again.
>
> My impression is that these drives do not honor the flush or FUA.
> (Directio uses flush or FUA right? you can be sure that data is on the
> platters after directio right? Anyway I also set fsync=1 and nothing
> changed)
O_DIRECT does not imply flush of FUA, I'm afraid. It arguably should use
FUA, but currently it does not.
--
Jens Axboe
next prev parent reply other threads:[~2011-01-03 11:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-02 4:12 Again on IOPS higher than expected in randwrite 4k Spelic
2011-01-03 11:05 ` Jens Axboe [this message]
2011-01-03 11:26 ` Spelic
2011-01-03 14:10 ` Jens Axboe
2011-01-05 11:45 ` Spelic
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