suggestions for SATA RAID cards

[Gibson, Jasen (GE Indust, ConsInd, consultant)]

-----Original Message-----
From: Pete French [mailto:petefrench at ticketswitch.com]
Sent: Wednesday, October 04, 2006 10:50 AM
To: freebsd-amd64 at freebsd.org; Gibson, Jasen (GE Indust, ConsInd,
consultant); killing at 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.