Re: "big" machines running Debian?
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.
If my understanding is off, I'd have to find it in the manual.
Doug.
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