Date: Mon, 30 Oct 2006 17:38:09 +1030 From: Greg 'groggy' Lehey <grog@FreeBSD.org> To: "R. B. Riddick" <arne_woerner@yahoo.com> Cc: performance@freebsd.org Subject: Re: gvinum raid5 performance seems slow Message-ID: <20061030070809.GJ1052@wantadilla.lemis.com> In-Reply-To: <20061030070532.5495.qmail@web30309.mail.mud.yahoo.com> References: <20061030051913.GG1052@wantadilla.lemis.com> <20061030070532.5495.qmail@web30309.mail.mud.yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
--4vpci17Ql0Nrbul2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sunday, 29 October 2006 at 23:05:32 -0800, R. B. Riddick wrote: > --- Greg 'groggy' Lehey <grog@FreeBSD.org> wrote: >> "Sufficiently large data blocks" equates to several megabytes. >> Currently MAXPHYS, the largest transfer request that would get to the >> bio layer, is 131072 bytes. This would imply a stripe size of not >> more than 32 kB for a five disk array, which is unrealistically small. >> >> I did consider this optimization, but it would only work if Vinum were >> first to buffer multiple requests, and there are all sorts of >> reliability issues there. For example, you'd have to lie about the >> first few requests that were only buffered and not actually sent out >> to disk. Possibly it should be done anyway. >> > I did it that way in my graid5 class: > http://home.tiscali.de/cmdr_faako/geom_raid5.tbz I would have taken a look at it if the sources had been directly web viewable. > The source might look somehow incomprehensible, Heh. I know the feeling :-) > but it seems to be quite stable (on amd64 and i386)... > > > I tried to benchmark with a 3 disk array: > Single disk: 30MB/sec write speed > graid5 device: 20MB/sec write speed Can you give more details? Stripe size, request size, number of concurrent accessors, etc.? > I would be interested in other benchmarks about it. Try rawio. Greg -- See complete headers for address and phone numbers. --4vpci17Ql0Nrbul2 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFFRaTZIubykFB6QiMRArD6AJ4ygV+/v2wMI9+pOnBAWDYE9yecPACfTA18 0K8V4QRRIS1wG+qq14zlb4k= =R5eA -----END PGP SIGNATURE----- --4vpci17Ql0Nrbul2--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20061030070809.GJ1052>