[linux-lvm] Re: [Announce] device-mapper beta3 (fast snapshots)
Patrick Caulfield
caulfield at sistina.com
Tue Jul 16 13:05:02 UTC 2002
On Tue, Jul 16, 2002 at 01:27:24PM -0400, Chris Mason wrote:
> On Tue, 2002-07-16 at 12:31, Joe Thornber wrote:
>
> > > Joe, are you absolutely sure these tests had the disk cache disabled? That's
> > > the only hardware thing I can think of that would make a difference.
> >
> > Absolutely sure. Those figures were for a pair of PVs that were
> > sharing an IDE cable so I can certainly get things moving faster.
>
> Some IDE drives ignore commands to turn off the write back cache, or
> turn it back on when load gets high.
>
I have reproduced Joes flat graph with SCSI & Fibre-channel drives so I wouldn't
read too much into his cabling :-)
patrick
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