On Wed, Mar 26, 2003 at 04:57:11PM -0800, Barton Robinson wrote:
> Without PAV, having Linux issue 3 I/Os to the same physical
> volume will NOT help performance. If one of those I/O must
> be satisified by activity to a real disk, all of the remaining I/O
> queued on the device will wait, even those with data residing
> in cache who could be satisfied immediately.

(I think I'm just going to hire Alan Altmark to explain what I'm
trying to say  -- I can't seem to express myself very well these
days. Alan seems to be good at explaining me...8-()

My original point was to break up the big minidisks or full
volumes into smaller pieces that you can move around to avoid the
problem of blocking on a single I/O to a device.

Since VM PAV support is still not in the cards, the technique does help
simulate the same effect, and thus, is an improvement over fullpack
minidisks or dedicated volumes.

-- db

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