On Fri, 27 Sep 2013 14:41:54 -0400 (EDT), Tom H <tomh0...@gmail.com> wrote: > > I couldn't care less how many disks you have. > > Defaulting to the use of UUIDs isn't some wacky whim but a > well-reasoned technical decision, unless you want to claim to know > more than the developers putting together distributions. > > This isn't a question of "/dev/sdX works for me, yay!" The issue is > that device names aren't NECESSARILY stable (some would say that > they've never been so) so, distributions are using UUIDs in order to > avoid having any Linux user anywhere be unable to boot because sda is > now sdc, sdb is now sda, and sdc is now sdb...
+1 Well said. By the way, even if you only have one hard disk, you can still get into trouble. For example, I have a one-hard-disk system where my hard disk normally shows up as /dev/sda and my CD-ROM drive normally shows up as /dev/sr0. But if I boot from the CD-ROM drive using a Debian installer CD in rescue mode, my CD-ROM drive shows up as /dev/sda and my hard disk shows up as /dev/sdb! Specifying the device name for the permanent root file system is not the only problem. Suspend/resume is another example. The suspend partition is identified by the Debian installer in /etc/initramfs-tools/conf.d/resume by means of a UUID. The Debian init scripts try to process a resume image *before* they attempt to mount the permanent root file system. (By the way, this tells you that /etc/initramfs-tools/conf.d/resume is one of the files that gets built in to the initial RAM file system; so if you change it you must rebuild your initial RAM file system.) If you don't use an initial RAM file system, you may have trouble with getting suspend/resume to work, or to work properly. Early loading of CPU microcode upgrades is another example. The point is that the architects of the Debian init scripts pretty much assume that an initial RAM file system is used, and they take advantage of that assumption when they write their init scripts. Although it is still possible to create a kernel that does not use an initial RAM file system, that doesn't mean that it is a good idea. As time goes on, one is likely to encounter more and more problems as the result of swimming upstream against the way the system is designed to work these days. On s390x hardware, I have a Debian Linux system that has four disks. These disks are assigned the device names /dev/dasda, /dev/dasdb, /dev/dasdc, and /dev/dasdd by the kernel. But the correspondence between these Linux device names and the hardware device numbers varies widely from boot to boot. I can assure you of that from personal experience. -- .''`. Stephen Powell : :' : `. `'` `- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/1332555544.3411509.1380325292433.javamail.r...@md01.wow.synacor.com
