Subject: Re: Suggestions on CCD Interleave (also, large-block large-cyl UFS)
To: firstname.lastname@example.org, Curt Sampson <email@example.com>
From: Dave Sainty <firstname.lastname@example.org>
Date: 02/02/1999 09:21:56
Curt Sampson writes:
> This would still display the same problems WRT even numbers of
> _interleave_, since nothing's changed as far as which disk it's
> going to hit for a particular block on the ccd.
> I expect the asymmetry is happening because the inode blocks end
> up concentrated on one disk when a power-of-two interleave is used.
> This might affect even small interleaves, because I'd bet that ffs
> uses the inodes in a cylinder group in order from the beginning.
> It'd be nice to have a detailed analysis of just what changes you
> can expect to see on a ccd given different interleaves.
It'd be great if it were possible to gather a record of all disk IO
operations, then simulations on real data could be run, and any such
effects would presumably be simpler to diagnose.