How to fstab

[Peter Cordes]

I just discovered that the default fstab line for /cdrom isn't good when you have a dvd with a file >4GB on it, which requires UDF. It should be iso9660,udf, not udf,iso9660. mount seems to try filesystems in reverse order, so putting it last makes it get tried first. edit: mount only tries the last one. reversing the order makes it fail to mount normal discs without UDF filesystems. I'll file a bug report.

I'm posting here because it took me a while to figure this out, but I don't know if it should be considered a bug, and if so what package is responsible for the default /etc/fstab anyway.

You make such a disk by using the latest version of growisofs/genisoimage (in Gutsy testing, but not Feisty.) The -allow-limited-size option makes an iso9660 filesystem with the file sizes truncated to 32 (or 31) bits, and a UDF filesystem with the proper sizes.
http://geekpit.blogspot.com/2007/02/...ups-under.html
(This option is supported by the latest k3b, but k3b doesn't work in my gutsy chroot. It can't see the filesystem and complains about file:/// URLs. I don't know where all the sockets are for the kde IPC stuff...)

Anyway, so if you write the image to a file (genisoimage -o), and mount -o loop, Linux will use the UDF filesystem structures because /proc/filesystems lists udf before iso9660. This means the directory listing shows a 4.3GB file, in my case. Burning to a disk and doing mount /cdrom makes Linux use the iso9660 (+Rock Ridge) filesystem, which means my directory listing shows a 300MB file. With sudo mount -t udf ... I can mount the optical disc and see the 4.3GB file. The only problem anywhere with this is that Ubuntu defaults to trying iso9660 first.

BTW, it's only a problem if you have a disc with a bogus iso9660 filesystem, like genisoimage creates with -allow-limited-size. Otherwise I don't know of a reason why you'd rather have UDF instead of RR. genisoimage can't currently create images with no iso9660 filesystem, apparently because they don't trust their UDF code enough.

BTW, I like to use these options for growisofs to master+burn large files all in one go:
growisofs -volid 'disc name' /dev/dvd -speed=6 \
-use-the-force-luke=notray -dvd-compat \
-use-the-force-luke=bufsize:32m \
-allow-limited-size -udf -rational-rock \
-allow-leading-dots -full-iso9660-filenames -relaxed-filenames -allow-lowercase \
-no-iso-translate -allow-multidot -omit-period -iso-level 3 \
-graft-points -f \
foo.vol000....par2 foo foo.vol128...par2

(par2 is forward error correction data to make the data recoverable in case of scratches. Not putting all the recovery files next to each other on disc should give you a better chance of not losing them all. growisofs orders files in the image in the order they appear on the command line.)

Usually I use k3b to set up and burn. I even have some perl scripts that I can run on a k3b project file to create par2 files for the set of files that will be on the CD. (I should publish those somewhere... email me if you want them.)

[sneax]

Hi, i found this thread through search. I have a problem with fstab. I like this guide but it's not completely clear.

I have made an entry for my removable usb hard disk, it mounts ok (but I have to do mound manually) is there a way so that it would mount the hard disk as soon as I plug it in (hotplug)? It was like that when installing ubuntu but ntfs-config broke that so I'm trying to remake my fstab.

Also, I want to use an external usb stick and put it in fstab but when I do this command to list uuid and label it doesn't show my stick! So I don't know the label/uuid to put it in fstab!

WHen I list the 'id' then it shows the usb stick.

I can also mount the usb stick fine as root but i want it to automount (hotplug) and be usable as user.

Any ideas?

[bodhi.zazen]

Hi, i found this thread through search. I have a problem with fstab. I like this guide but it's not completely clear.

I have made an entry for my removable usb hard disk, it mounts ok (but I have to do mound manually) is there a way so that it would mount the hard disk as soon as I plug it in (hotplug)? It was like that when installing ubuntu but ntfs-config broke that so I'm trying to remake my fstab.

Also, I want to use an external usb stick and put it in fstab but when I do this command to list uuid and label it doesn't show my stick! So I don't know the label/uuid to put it in fstab!

WHen I list the 'id' then it shows the usb stick.

I can also mount the usb stick fine as root but i want it to automount (hotplug) and be usable as user.

Any ideas?

I assume you are using gnome?

gnome auto mounts removable devices with gnome-volume-manager (which has always been hard form me to configure).

I find that gnome-volume-manager does NOT like it if you have an entry in fstab for flash/usb drivers, so I would remove the fstab entry, unmount the device, remove the device, delete the mount point in /media, and reboot. The re-try the device.

I do not user ntfs at all, I use FAT to windows share, so I do not know if it will work or not, but set a label on your ntfs partition and see if that help.

[mssever]

I have made an entry for my removable usb hard disk, it mounts ok (but I have to do mound manually) is there a way so that it would mount the hard disk as soon as I plug it in (hotplug)? It was like that when installing ubuntu but ntfs-config broke that so I'm trying to remake my fstab.

That used to work for me, but after recently upgrading my server to Feisty, my fstab-listed vfat USB drive no longer automounts, either. I noticed that Feisty renamed a bunch of things. My disks changed names from hd* to sd*, and my external drive's symlink in /dev/disk/by-id was renamed. This renaming broke my fstab, of course (I refuse to use UUIDs, since IMO there is no sane reason to use such unreadable identifiers when suitable alternatives exist).

I believe that pmount is responsible for automounting.

I can also mount the usb stick fine as root but i want it to automount (hotplug) and be usable as user.

You didn't say what format your USB stick was. For vfat, I use the following in the options column of fstab:

uid=1000,gid=1000,umask=077

uid is your normal user's numeric user ID as listed in /etc/passwd. gid is for the group ID as listed in /etc/group. These control which user owns the files on disk. Finally, the umask sets up the permissions. Setting it to 000 would allow all users full control.

I have no issues with my ntfs-3g partition, so if that's the one you're having issues with, I don't know how to help you.

==================

By the way, if you still can't manage to get anything that's mentioned in fatab to be automounted, you might be able to hack the pmount source code to force pmount to use the options you want (which, last I checked were hard-coded), then re-compile pmount. This process, however, isn't for the faint of heart.

[theDaveTheRave]

Hello All.

Great info in here and I have read with some interest - I think it may have solved an issue I had with a partition not being accessible by my "almost never used" Vista partition (but then who would want to use it!?).

OK so my problems / solutions.

I think I had my share partition set to the wrong type untill I read this howto I mistakenly thought vfat and fat32 were "simlar" and readable by ******* - I have now changed my fstab to set it as NTFS-3g.

More alarmingly I am confused about how I set a label?? probably me just being dopey / sleepy / snoozey and waiting for snow white to show up and help out.... - maybe Bodhi is SnowWhite in disguite??

Anyway onto my main problem.

I have an issue with the UUID of my linux swap partition changing on a "Semi regular basis" - this means that each time I boot up I have to check that I have my swap in place - or else my system does a serious go-slow.

A serious go slow is tantamount to the old MS blue screen of death, so I use the power switch to turn off then reboot. this seems to bugger up the uuid of my swap partition, oddly enough it has no effect on any of the others!?

Personally I am not too bothered with the loss of the swap, it s a nuisance more than anything and it keeps me on my toes and mens I have to remember some admin stuff (regular training is allways a good way to stay in shape I say), what gets me is what is causing it to happen??

what solutions can I use?? if I set a "label" will this work or does it map to the uuid??

Any thoughts would be greatly appreciated and more than welcome.

hope to hear from you soon.

Dave

[mssever]

I have an issue with the UUID of my linux swap partition changing on a "Semi regular basis" - this means that each time I boot up I have to check that I have my swap in place - or else my system does a serious go-slow.

A serious go slow is tantamount to the old MS blue screen of death, so I use the power switch to turn off then reboot. this seems to bugger up the uuid of my swap partition, oddly enough it has no effect on any of the others!?

I don't really care for using UUIDs. If I were you, I'd list the actual device name in fstab (e.g., /dev/hda3). That should be a stable name (except that the upgrade from Edgy to Feisty inexplicably renames hd* disks to sd*.)

I really don't know what could be causing the swap partition to change UUIDs, though.

Before I increased the amount of swap I have, I experienced numerous serious slow downs, like you do. Normally with a lot of patience I could eventually log in via SSH and kill off the memory-hogging program. Of course, sometimes there's just nothing you can do but

<Alt><SysRq>E 
<Alt><SysRq>I
<Alt><SysRq>S
<Alt><SysRq>U
<Alt><SysRq>B

(which is a little nicer than using the power button)

[theDaveTheRave]

mssever

I had forgotten about the <alt><sysrq>.... trick, In fact I though that there was an even quicker one that that??

couple of silly questions though,

which key is the <SysRq>, is it synonomous with the <ctrl> key or is it the <windows> button that is on keyboards these days?

query on the line of code I need for my fstab,

currently the offending part reads ( I have included the notes that I have commented out in the file as well, in case is helps!

#Entry for /dev/sda6 - to hold a file for memory swap.
# seems that the UUID has changed?? how and why? now funcions as
# today 24July07<< dev/sda6: UUID="6fa837b7-46f9-448e-b4b9-b72929cc76be" TYPE="swsuspend" >>
#UUID=6fa837b7-46f9-448e-b4b9-b72929cc76be /dev/sda6 swap default 0 0
#required to change again as of 24 Aug 08
#UUID=a5a030a0-0955-46c4-9569-815f04a56635 /dev/sda6 swap default 0 0

#has changed again 25 Aug 08!
UUID=157abc4f-3652-4cb4-80c0-7819d56575ba /dev/sda6 swap default 0 0

do I simply put in the "link" FQN of the drive (in this instance it is < /mnt/swap> )

In fact I will try this and report back in a few minutes.

Dave

OK I had a play and it doesn't seem to have worked

the line in the fstab now reads

/dev/sda6 /mnt/swap swap default 0 0

I'll keep working on it, I'll reboot then come back in a few hours - just off to break the rest of our old/new kitchen!

Dave

ps. I've rebooted and it all seems to work, oh what joy.

Thanks Bodi, Thanks mssever

now I just need to try breaking it by using the power button!!! hmmm, maybee later....

[mssever]

I had forgotten about the <alt><sysrq>.... trick, In fact I though that there was an even quicker one that that??

couple of silly questions though,

which key is the <SysRq>, is it synonomous with the <ctrl> key or is it the <windows> button that is on keyboards these days?

SysRq is the same key as Print Screen. You can learn more from Wikipedia. Here's what the <Alt><SysRq> combos I use mean (there are others, as well):

1. E: Send SIGTERM to all processes. SIGTERM is a request to the program to exit normally and clean up after themselves. Be sure to allow enough time for programs to exit.
2. I: Send SIGKILL to all processes. This signal causes the kernel to immediately kill the process without trying to be nice.
3. S: Sync the disks. Be sure to allow sufficient time here, too.
4. U: Remount the disks read only
5. B: Reboot

When it comes to your fstab, here's mine for reference:

/dev/hda6 none swap sw 0 0

As far as I know, the second field--which is traditionally "none"--can be anything you want, since the swap partition is not mounted as a part of the filesystem and consequently has no mountpoint.

[FrankVdb]

I read somewhere that from Edgy upwards, one needs to replace the device name (e.g. /dev/sda1) with its UUID in the fstab. Under Feisty, this only applies to scsi or scsi-emulated drives!

When adding two drives (an IDE and an SATA drive) to one of my PC's, I noticed that the IDE drive I added (/dev/hdb1) went unnoticed when mentioned by its UUID in fstab! It took me a long time to find that out, messing around with countless option alternatives before it dawned to me that the UUID just did not work.

I'm actually using Linux Mint, which is Feisty plus multimedia support out of the box.

[mssever]

I read somewhere that from Edgy upwards, one needs to replace the device name (e.g. /dev/sda1) with its UUID in the fstab. Under Feisty, this only applies to scsi or scsi-emulated drives!

When adding two drives (an IDE and an SATA drive) to one of my PC's, I noticed that the IDE drive I added (/dev/hdb1) went unnoticed when mentioned by its UUID in fstab! It took me a long time to find that out, messing around with countless option alternatives before it dawned to me that the UUID just did not work.

I'm actually using Linux Mint, which is Feisty plus multimedia support out of the box.

Actually, you don't have to use UUIDs. Edgydoes it that way, but I prefer other mechanisms: /dev/{h,s}d*, /dev/disks/by-*, etc.

Also, in Feisty, all disks are now sd*. There is no such thing anymore as /dev/hda1. I think that this was actually a kernel change, but I'm not positive about that.