Subject: Re: Suggestions on CCD Interleave (also, large-block large-cyl
To: Greywolf <email@example.com>
From: Curt Sampson <firstname.lastname@example.org>
Date: 01/31/1999 23:13:27
On Sun, 31 Jan 1999, Greywolf wrote:
> Is any of this useful on non-symmetric disks, i.e, I have differently sized
> partitions on differently sized disks.
I should think so. As I understand it, if the partitions are still
different sizes, the ccd will still be allocated as _interleave_
blocks from the first, followed by _interleave_ blocks from the
second, and so on. Once a partition runs out, I assume it's just
removed from the list, so with a 1GB and 1.2GB partition, you will
get the first 2 GB interleaved, and the last 200 MB at the end of
the 1.2 GB disk.
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.
Curt Sampson <email@example.com> 604 801 5335 De gustibus, aut bene aut nihil.
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