Re: SCSI disk devices

Theodore Y. Ts'o (tytso@MIT.EDU)
Mon, 5 May 1997 19:31:44 -0400

Date: Sat, 3 May 1997 19:33:34 -0400
From: Eric Youngdale <>

If I get a clear indication that this is the direction we want
to go, then scsidev can be cleaned up and enhanced (making it volume
label aware is one enhancement I wanted to add, especially now that
ext2 supports volume labels). It also should be made filesystem aware
too, I think so that it can recognize various types of filesystems
(this is a prerequisite to being able to snarf the volume labels).

I had always thought that the right approach would go far beyond
scsidev; if you have a volume management daemon that would automatically
do the right thing based on the volume ID (pretty much all filesystems
have them now: ext2, iso9660, even MS-DOS FAT), then who cares what the
device name is?

Have the volume management daemon take care of doing the filesystem
checking, the mounting, even the backup of fixed disks. It could query
the system for a list of block devices, and then probe each one looking
for filesystems. When it found one, it would use an internal database
to determine where a filesystem should be mounted (if it should be

You'd have a user interface client which could connect to the volume
management daemon and get a list of available filesystems, which the
user could mount (with certain restrictions to prevent this from turning
into a security hole). This client would also be used to initially
create filesystems --- the user interface could show the complete
description of each of the devices, and how they were connected to the
SCSI bus, with nice long verbose names to describe the SCSI adaptor and
the SCSI disk, since the user would be selecting disks from a pick list.

If properly managed, we could manage to completely hide block device
names from the user altogether, and let it be all managed from a
user-mode daemon. This would obviously be a lot of work, but I fancy
the end result would be really cool. :-)

- Ted