Date: Wed, 04 Oct 2006 15:49:47 +0100 From: Pete French <petefrench@ticketswitch.com> To: freebsd-amd64@freebsd.org, jasen.gibson@ge.com, killing@multiplay.co.uk Subject: Re: suggestions for SATA RAID cards Message-ID: <E1GV84B-0007V8-BB@dilbert.firstcallgroup.co.uk> In-Reply-To: <035801c6e7bd$3aad9f10$b3db87d4@multiplay.co.uk>
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> 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 ? -pete.
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