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From: phil@qfdts.OZ (Phil Chadwick)
Newsgroups: comp.unix.wizards
Subject: File system placement
Message-ID: <1294@qfdts.OZ>
Date: Wed, 6-May-87 19:14:07 EDT
Article-I.D.: qfdts.1294
Posted: Wed May  6 19:14:07 1987
Date-Received: Sat, 9-May-87 02:52:18 EDT
Organization: Department of Forestry, Queensland, Australia
Lines: 24
Keywords: location of key file systems for optimal access

The other day we lost a disk and during those tedious
hours it took to rebuild a usable system, I got to thinking...

On the day I first booted UNIX from release tape, root, swap,
tmp and usr were placed on the disk starting at cylinder 0.
Even though we (normally) have three disks and the important
files systems are now distributed over multiple drives, the
original file system layout concept is largely unchanged.

For optimal average access time, important file systems should
reside in the mid-range cylinders of a disk.  So why are our
disks still arranged with the most important (and subjectively,
the heaviest) access biased around the lowest cylinder numbers?

I am giving serious consideration to rearranging the larger
disks (say those > 300Mb) with root, tmp, swap and usr (not
including users' files) fair bang in the middle.  I can think
of only one significant disadvantage: available space will be
fragmented into two disjoint areas, however the bigger the disk
the smaller the problem.

Any comments?

Phil Chadwick