dan@rna.UUCP (Dan Ts'o) (11/02/88)
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@rna.rockefeller.edu Rockefeller Univ. ...cmcl2!rna!dan 1230 York Ave. rna!dan@nyu.arpa NY, NY 10021 tso@rockefeller.arpa tso@rockvax.bitnet