Re: "big" machines running Debian?

[Ron Johnson <ron.l.johnson@cox.net>]

On 02/26/2009 01:49 PM, Ron Peterson wrote:
> 2009-02-26_14:21:54-0500 "Douglas A. Tutty" <dtutty@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.

--
Ron Johnson, Jr.
Jefferson LA  USA

The feeling of disgust at seeing a human female in a Relationship
with a chimp male is Homininphobia, and you should be ashamed of
yourself.