README.changer

Fri Jan 21 17:31:43 GMT 2000
Toby Jaffey <toby@earth.li>
Added modules/mount_changer.c

I have an NEC CD-ROM DRIVE:251, 4X CD-ROM changer w/4 slots, 128kB
Cache.  The drive can only mount one CD at a time. To change the CD in
use you must unmount, swap slots (lots of ioctl() calls) and
remount. Using autofs, this module allows the illusion that all CDs
are mounted at any given time. Only when data is requested does the
drive need to swap. Clearly, this is awful for simultaneous reads
across many disks, but I use it to create mp3 playlists spanning
multiple CDs.

The code is mostly clean, but rather than adding a new "mediatype" to
the config file, I set my drive up as fstype=changer. The assumption
is made that all of the disks are of type iso9660. This is a bad
thing, but it works for me.

[hpa: I believe these problems are due to a design error.  The changer
should be a lookup type, rather than a filesystem (mount) type.]

My /etc/auto.master says:
/mnt/changer    /etc/auto.misc

My /etc/auto.misc says:
1          -fstype=changer              :/dev/hdb
2          -fstype=changer              :/dev/hdb
3          -fstype=changer              :/dev/hdb
4          -fstype=changer              :/dev/hdb