From: Aryeh Gregor <Simetrical+list@gmail.com>
To: MRK <mrk@shiftmail.org>
Cc: CoolCold <coolthecold@gmail.com>, Mario <mgiammarco@gmail.com>,
linux-raid@vger.kernel.org
Subject: Re: It is possible to put write cache on ssd?
Date: Wed, 9 Jun 2010 12:21:29 -0400 [thread overview]
Message-ID: <AANLkTimMBOtusTb2GQjziBEt5XoFEBEmZmQfhWsB6Xig@mail.gmail.com> (raw)
In-Reply-To: <4C0F75B8.7020306@shiftmail.org>
On Wed, Jun 9, 2010 at 7:06 AM, MRK <mrk@shiftmail.org> wrote:
> Same problem with write-mostly/write-behind I think. I don't know how long
> is the queue that holds data already committed to the SSD and not yet
> committed to the HDD but it can't be too long. I'm reading the "man md"
> right now and it's not extremely clear on this. I have the impression the
> queue between the two it's either the /sys/block/hdddevice/queue/nr_requests
> or it uses the write-intent bitmap (if set). In case of the nr_requests,
> it's gonna be very short so the SSD can give you quick bursts but continuous
> performance will be that of the HDD.
I tried this once and posted some bonnie++ results:
https://kerneltrap.org/mailarchive/linux-raid/2010/1/31/6742263
next prev parent reply other threads:[~2010-06-09 16:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-04 8:52 It is possible to put write cache on ssd? Mario
2010-06-07 19:14 ` Bill Davidsen
2010-06-08 4:54 ` Ian Dall
2010-06-08 19:28 ` Bill Davidsen
2010-06-08 22:48 ` David Rees
2010-06-09 9:31 ` Ian Dall
2010-06-08 7:31 ` Mario
2010-06-08 12:23 ` CoolCold
2010-06-09 7:49 ` Mario
2010-06-09 11:06 ` MRK
2010-06-09 16:21 ` Aryeh Gregor [this message]
2010-06-10 12:08 ` MRK
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