On Thu, Feb 26, 2009 at 03:21:44PM -0600, Ron Johnson wrote: > On 02/26/2009 01:49 PM, Ron Peterson wrote: > >2009-02-26_14:21:54-0500 "Douglas A. Tutty" <dtu...@vianet.ca>: > >>On Wed, Feb 25, 2009 at 08:53:45PM -0600, Ron Johnson wrote: > >>>On 02/25/2009 07:22 PM, Douglas A. Tutty wrote: > >>>[snip] > >>>>/proc/megaraid/hba0/raiddrives-0-9 > >>>>Logical drive: 0:, state: optimal > >>>>Span depth: 1, RAID level: 1, Stripe size: 64, Row size: 2 > >>>>Read Policy: Adaptive, Write Policy: Write thru, Cache Policy: Cached IO > >>>> > >>>>Logical drive: 1:, state: optimal > >>>>Span depth: 0, RAID level: 0, Stripe size:128, Row size: 0 > >>>>Read Policy: No read ahead, Write Policy: Write thru, Cache Policy: > >>>>Cached IO > >>>Why is Read Ahead disabled on Logical Drive 1? > >>My understanding is that "read ahead" in this case refers to the ability > >>of the raid card to read ahead from one disk while a read is taking > >>place on another disk. This only makes sense in a redundant raid level. > >>LD1 is raid0, so there is no other disk from which to read ahead. > > > >My understanding is that read ahead means the controller reads more data > >into memory than you asked for, expecting that the next bits you ask for > >will be immediately after the ones you just got. > > > > That *is* the standard definition. Though there's nothing stopping > Megaraid from being weird.
I just checke the setup in the bios and it is set for adaptive read-ahead on both LDs. I don't know what's wrong with the output from /proc. Doug. -- To UNSUBSCRIBE, email to debian-amd64-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org