[SOLVED] new fstab format?

newbiesforever · 10-17-2011, 01:51 AM

I just looked in the fstab file on my new Debian installation, because I wanted to edit it so a separate partition would be used for /home. But the format is different from what I've seen in the past on my other Linux installations. The contents are:

Code:

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# / was on /dev/sda5 during installation
UUID=cd9b49f1-836b-446e-bfd2-7c3613bae496 /               ext3    errors=remount-ro 0       1
# swap was on /dev/sda2 during installation
UUID=fa50d342-46e0-41b2-a163-b679a397e5b6 none            swap    sw              0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0
/dev/sdb1       /media/usb0     auto    rw,user,noauto  0       0

I expected it to look like this:

Code:

# Pluggable devices are handled by uDev, they are not in fstab
/dev/sda7 / ext3 defaults,noatime 1 1
/dev/sda2 swap swap sw,pri=1 0 0
proc /proc proc defaults 0 0
devpts /dev/pts devpts mode=0622 0 0
/dev/sda1 /home auto defaults,noatime 1 2
# Dynamic entries below
/dev/sda3 /mnt/sda3 ext3 noauto,users,exec,relatime 0 0
/dev/sda5 /mnt/sda5 ext3 noauto,users,exec,relatime 0 0
/dev/sda6 /mnt/sda6 ext3 noauto,users,exec,relatime 0 0
/dev/sdb1 /mnt/sdb1 vfat noauto,users,gid=users,dmask=002,fmask=113,relatime 0 0
/dev/cdrom /media/cdrom udf,iso9660 noauto,users,exec,ro 0 0
/dev/sr0 /media/cdrom udf,iso9660 noauto,users,exec,ro 0 0

Has the format of fstab been changed, as grub was changed to grub 2 sometime recently? I don't know how to edit this new format, and the line I'm looking for isn't there. I want to tag /sda1 as the /home partition, but it (and none of the sda1 partitions) are mentioned. I suppose they've been moved to another file? If so, what is it?

weibullguy · 10-17-2011, 01:57 AM

fstab has been using universally unique identifiers (UUID) for quite awhile now in many, if not most, distros. It still understands the sd*[0-9] syntax too. The blkid command will provide you the UUID for each hard drive partition. So too will ls -l /dev/disk/by-uuid

acid_kewpie · 10-17-2011, 01:59 AM

those partitions clearly are mentioned, what do you think

UUID=cd9b49f1-836b-446e-bfd2-7c3613bae496 / ext3 errors=remount-ro 0 1

is as it's clearly mounting an ext3 partition to /

the use of UUID's mean that if you reconnect that drive as sdb, or mess with partitions, it'll still be found without issue. it IS the same format.

DavidMcCann · 10-17-2011, 10:54 AM

The use of UUIDs can have its drawbacks. I have a guest partition for testing new distros. If the installer changes its UUID, or that of the swap partition (and it has happened), my main distro won't boot. Nowadays, I re-write my fstab to use /dev designations.

newbiesforever · 10-17-2011, 11:16 AM

Quote:

Originally Posted by weibullguy

fstab has been using universally unique identifiers (UUID) for quite awhile now in many, if not most, distros. It still understands the sd*[0-9] syntax too. The blkid command will provide you the UUID for each hard drive partition. So too will ls -l /dev/disk/by-uuid

Quote:

Originally Posted by DavidMcCann

The use of UUIDs can have its drawbacks. I have a guest partition for testing new distros. If the installer changes its UUID, or that of the swap partition (and it has happened), my main distro won't boot. Nowadays, I re-write my fstab to use /dev designations.

I see...so until I get the hang of the new syntax, I am not required to use it?

MEPIS 11 and antiX must not be using the new format yet, because the Fstab files on my installations of those are written in the old format.

SecretCode · 10-17-2011, 02:36 PM

Quote:

Originally Posted by newbiesforever

I see...so until I get the hang of the new syntax, I am not required to use it?
... the Fstab files on my installations of those are written in the old format.

I have not heard anywhere that the UUID format is "preferred" or the way of the future. It's just another option and you don't need to convert to it

From man fstab (my bold):

Quote:

Instead of giving the device explicitly, one may indicate the (ext2 or xfs) filesystem that is to be mounted by its UUID
or volume label (cf. e2label(8) or xfs_admin(8)), writing LABEL=<label> or UUID=<uuid>, e.g., `LABEL=Boot' or
`UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'. This will make the system more robust: adding or removing a SCSI disk
changes the disk device name but not the filesystem volume label.

newbiesforever · 10-17-2011, 03:28 PM

Quote:

Originally Posted by SecretCode

I have not heard anywhere that the UUID format is "preferred" or the way of the future. It's just another option and you don't need to convert to it

From man fstab (my bold):

Great. The other way is less complicated, at least in my opinion.

acid_kewpie · 10-17-2011, 04:01 PM

pen and paper is "less complicated". So is DOS 6.2.

newbiesforever · 10-17-2011, 04:45 PM

Quote:

Originally Posted by acid_kewpie

pen and paper is "less complicated". So is DOS 6.2.

No one was proposing to use pen and paper instead of a computer, good sir; and if you're seriously suggesting that preferring simplicity would or should lead me to quit using computers at all, that's probably a slippery-slope argument. There's a difference between the top of the slope and the bottom. So some things are less complicated than others, eh? Really!--I never would have guessed.

Anyway, When something I've been doing works fine, such as the old Fstab format or KDE 3, I generally have no interest in changing it. The programmmers out there can fool around with these things all they want to, because that's their hobby and/or line of work; but it's not mine, so on my computer, unless I feel like doing something new just for the hell of it, I'll pass on using this other Fstab format.

David the H. · 10-18-2011, 01:16 AM

The main point of UUID is that it will mount that partition, and only that partition, even if something happens to alter the device entry, and it will also prevent mounting if someone swaps out the drive with another one. It will only fail if you do something to change the UUID, as mentioned.

It was added to provide a more hardware-specific way to handle block devices; one that's not dependent on bus location or order of detection.

By the way, as kind of a middle ground, you can also designate the partition to mount by label. If a partition with the given label is detected, the system will mount it to that location, again no matter what the /dev entry says. But it's a bit weaker than UUID because it's not uncommon for multiple drives with identically-labeled partitions to exist.

Of course that can come in useful too, at times.