On Monday 31 January 2005 07:35, Paul Howarth wrote:
Robert Storey wrote:
> What's confusing to me here is that, in Fedora, I can't figure out which
> partition is mounted where. Is my / partition /dev/hda3, or /dev/hda5,
> or ??? Ditto for swap, or any other partition. If I wanted to make
> some change in the partition table (for example, adding a /home
> partition) I have no idea how I could get /etc/fstab to recognize it.
>
> I've tried making some sense out of fstab-sync, but so far it's pretty
> opague. Where does Fedora store the partition information? Anybody know
> some links that can explain this messy filesystem table?
If you just run the command "mount" (you don't have to be root),
you'll
see which partitions are mounted where. You can use either hardcoded
partition names such as "/dev/hda7" or filesystem label references such
as "LABEL=/home" in /etc/fstab; either will work OK. You can assign a
label to a partition when you create the filesystem on it by using the
-L option in mke2fs, and you can set or change the label of an existing
partition using the -L option in tune2fs.
or display and change labels with e2label
But why label in the first place? I wondered about that for a while and came
to this conclusion: If a drive in an Intel-like box is changed from master
to slave or primary IDE channel to secondary or some other combination then
the device name changes, e.g., /dev/hda1 to /dev/hdb1. When booting after
this change without fixing /etc/fstab, mount cannot find /dev/hda1 because of
its new location at /dev/hdb1. By labeling partitions and using the labels
in /etc/fstab, mount will search all available partitions for the one with
the name specified in /etc/fstab (or mount command). This eliminates the
problem of device names changing when modifying the drive configuration.
Labeling does introduce a problem: What happens if 2 partitions have the same
label? Which one does mount choose? I do not know the algorithm but I do
know that mount does not know which one you want to use. In the technical
college where I taught Unix/Linux system administration we had removable IDE
drives in our lab machines. (standard IDE drives in a tray that slides into a
bay the in cabinet. works good. I use them at home too) I had a removable
drive bay on my office machine. A couple of times I had to make some repairs
to corrupted student drives. Since the drives are not hot-swappable I
would power down my machine, insert the student's drive, power up and boot.
Their partition labels were the same as on my internal IDE drive and as a
result would bet mounted instead of my partitions. After a couple time of
messing with that I changed the /etc/fstab file on my system to use device
names instead of labels.
fsck also recognizes the labels, probably other disk related commands too.
paul
--
Paul F. Almquist
paul(a)almquist.name
Eau Claire, WI USA