-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Bob McGowan wrote: > Michael Pobega wrote: [snip] >> >> I think UUID is used because it is better to use UUID to recognize the >> drives than /dev. For example, if you're trying to have your USB drive >> automount to /mnt/usb, you'd use something like "/dev/sdb1" in fstab, >> correct? What if you plug in an external drive? That will be picked up >> at /dev/sdb, and following that the USB thumbdrive will be picked up as >> /dev/sdc. The reason for UUIDs is to make it so that the computer can >> recognize the drives by their device ID rather than the order they were >> plugged in. >> >> I may be wrong though. This is what I've been told. >> > > This is correct, but is a 'high overview' level description. A few more > details, maybe, will help understanding what's going on (and the only > downside I know for it). > > First, the UUID and LABEL methods work in basically the same way, but > the UUID is generally considered better, particularly for drives that > migrate between systems (such as USB or Firewire). There is less of an > issue with colliding values between multiple systems using the UUID. > > On booting, the system scans devices and determines the UUID (or LABEL), > and creates symlinks from the UUID/LABEL directories (/dev/disk/by-uuid > or /dev/disk/by-label) pointing to the actual device node associated > with the UUID/LABEL. > > So the system can find a device node, using the LABEL or UUID. Once > found, the system uses the device node. It's this that leads to the > single 'downside' that I've seen, of using UUID/LABEL: > > Once mounted, the system 'forgets' the UUID/LABEL, so output of the > 'mount' command lists device nodes. Same for 'df'. > > And, KwikDisk (KDE applet) will show two items for a particular mount > point, the content from fstab (LABEL/UUID) and the device node actually > mounted and used to access the device. It's pretty quickly obvious (for > the moderately experienced user) which element to use to umount the > device, but the multiple entries can become confusing if you have > several disks or partitions set up this way.
Thanks Bob, for the clear explanation. Now I understand why in Windows when one wants to "safely remove" a device it shows a list of things that make it very hard to figure out what to click on. That of course has little bearing on my now since I dumped my MS baggage. I can understand the usage of UUID on removable drives, but it seems the new way of dealing with *all* disks is UUID. Why this needs to be so for normal hard drives remains a mystery to me. Joe - -- Registerd Linux user #443289 at http://counter.li.org/ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGLjAoiXBCVWpc5J4RAv+uAJ49DeYyoYYS80YDKrXfddx1+mxSYQCfXRhi PmhNsOPGTW8mwgkXRXvDGSs= =aIkC -----END PGP SIGNATURE----- -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
