From: Ray Morris <support@bettercgi.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] mirror_region_size default: 4096 six times faster than 512?
Date: Mon, 27 Feb 2012 14:40:29 -0600 [thread overview]
Message-ID: <20120227144029.49ebea1a@bettercgi.com> (raw)
In-Reply-To: <CAOAgVpyHgVjaubZGH3kwfBqiYyU7vBNCBHmQjPMnrT_F6otZbQ@mail.gmail.com>
> copying chunks of a few MBs seems to always beat copying
> > bytes or KB per chunk.
> What kind of RAID? Anything that involves parity is going to require
> small writes to read and merge the new data into blocks and rewrite
> the parity.
At least mdadm RAID1 and RAID5. Hardware raid5 was slow with 512,
but not yet tested with 4096 or higher. I'll test it in a few days
after a migration completes.
--
Ray Morris
support@bettercgi.com
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On Fri, 24 Feb 2012 09:57:30 -0600
Les Mikesell <lesmikesell@gmail.com> wrote:
> On Thu, Feb 23, 2012 at 10:46 AM, Ray Morris <support@bettercgi.com>
> wrote:
> > 512 byte sector consumer SATA drives from Seagate and Hitachi.
> > Drives attached to a 9560 RAID card exhibited more difference than
> > drives in a different system attached to the motherboard directly.
> > As I mentioned, I haven't done extensive or highly scientific
> > testing, but in general, across various hardware using various
> > software, copying chinks of a few MBs seems to always beat copying
> > bytes or KB per chunk.
>
>
> What kind of RAID? Anything that involves parity is going to require
> small writes to read and merge the new data into blocks and rewrite
> the parity.
>
prev parent reply other threads:[~2012-02-27 20:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-21 16:29 [linux-lvm] mirror_region_size default: 4096 six times faster than 512? Ray Morris
2012-02-21 16:50 ` Alasdair G Kergon
2012-02-21 17:01 ` Les Mikesell
2012-02-23 16:46 ` Ray Morris
2012-02-24 15:57 ` Les Mikesell
2012-02-27 20:40 ` Ray Morris [this message]
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