Date: Wed, 4 Oct 2006 10:53:33 -0400 From: "Gibson, Jasen \(GE Indust, ConsInd, consultant\)" <jasen.gibson@ge.com> To: "Pete French" <petefrench@ticketswitch.com>, <freebsd-amd64@freebsd.org> Subject: RE: suggestions for SATA RAID cards Message-ID: <888F5D88060A214ABEFED0011CF186620117B916@LOUMLVEM03.e2k.ad.ge.com>
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-----Original Message----- From: Pete French [mailto:petefrench@ticketswitch.com] Sent: Wednesday, October 04, 2006 10:50 AM To: freebsd-amd64@freebsd.org; Gibson, Jasen (GE Indust, ConsInd, consultant); killing@multiplay.co.uk Subject: Re: suggestions for SATA RAID cards > I had similar issues as you say with read being much slower than write > using a highpoint controller the fix was to change the default block > size of the array to the min the controller supported. > >Does anyone have a good feel for a blocksize to use on RAID 1 under >FreeBSD ? I know for a system serving pparallel requests the usual = advice >is to have it as large as possible to try and get a single file onto >a single drive, so two in parallel read from a drive each - but for = large >files and a single read, do you want to make it somewhat smaller to = exploit >parallelism between the drives for a single request ? I have a pair of >drives running as RAID 1 and it is fairly obvious that for a large read = it >is alternating between then, rather than reading from both in parallel. >The stripe size there is 64k, what are other people using ? I believe mine is still set at 256k, which may be my issue, if Steven's = suggestion is correct.
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