Optimizing BSD filesystems for slow storage media (e.g. WORMS?)

[Dan Ts'o]

	Can someone email me a quick primer on suggestions of easy (and
moderately hard) ways to tune a 4BSD filesystem such that when transfered
to a slow storage media, will give good performance ?
	Basically the idea is (as an easy way to get started using an
optical WORM), to build a 4BSD filesystem on an Eagle and then raw copy it
to the WORM and mount the WORM read-only. However the WORM is slow in
transfer rate (~100kb/s) and seek time (~80ms). How should the readily
accessible tuning parameters of the BSD filesystem be set for such a media ?
How can you arrange the filesystem to allocate file space either mostly
contiguously or interleaved such that given the media specs like those above,
the next sector of interest is available when the CPU is ready (MVAX II) ?
Does the fact that the disk protocol is SCSI influence these choices ?
	A final note is that the Maxtor WORM has minimum 2kb sectors. Most
4BSD drivers assume 512byte sectors. Does the 4.3BSD (and Ultrix 2.0)
filesystem allow 2kb fragments (I don't think 4.2BSD did) ? Does it seem
wiser to hide the 2kb/sector limitation in the driver by buffering up in
the driver ? (Would certainly help file size granularity losses...)
	Please email responses. Thanks.
				Cheers,
				Dan Ts'o		212-570-7671
				Dept. Neurobiology	dan at rna.rockefeller.edu
				Rockefeller Univ.	...cmcl2!rna!dan
				1230 York Ave.		rna!dan at nyu.arpa
				NY, NY 10021		tso at rockefeller.arpa
							tso at rockvax.bitnet