Mounting III (Errors)

Summary:

• "maximal mount count reached - check forced"
• "device was not cleanly unmounted on shutdown - check forced"
• "mount: only root can do that"
• CD-Rom Tray Is Blocked
• 'df' doesn't list external media anymore
• "mount: can't find /mnt/{device} in /etc/fstab or /etc/mtab"
• '{device} is not a valid blockdevice'
• Audio CDs Don't Play When Mounted
• "input/output error"
• No Proper Unmounting ('Device Busy')
• No User Access To Files On Mounted Windows Partitions
• Trouble Mounting Removable Media With Different File Systems

"maximal mount count reached - check forced"

This is not an error, it's a feature ;-). After a specified number of reboots Linux checks the file system for consistency even if the box has been shutdown properly. This can take some time, especially on large partitions. You can set the interval with 'tune2fs' .

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"device was not cleanly unmounted on shutdown - check forced"

You either haven't run 'shutdown' before turning the machine off or were forced to reboot the machine because of a system freeze. The Linux file system is very robust and usually you'll get away with a long file system check. If you are unlucky, however, vital system files may have been damaged. Keeping '/' on a small partition of its own minimizes this risk.
Mandrake Linux 8 and later offer you a variety of 'journalizing' file systems to replace extfs2. Journaling file systems keep track (a 'journal') of all read / write operations. So even in case of abrupt system failure, the status of the system will be preserved and no checks will be run at reboot.

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"mount: only root can do that"

You have tried to mount a device that is not listed in '/etc/fstab' as being mountable by users (option 'user'). Do it as root. If you need to mount the device more often, it may be a good idea to change '/etc/fstab' accordingly.

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CD-Rom Tray Is Blocked

The CD-Rom is still mounted. Unmount it and you'll be able to open the tray again. By the way, if you want to unmount a CD and have it ejected right away, use the 'eject' command ('eject' RPM): eject /dev/cdrom. This works for all kind of removable media.

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'df' doesn't list external media anymore

The 'supermount' mechanism prevents 'df' from showing external media. To see them you have to supply the mount point as a parameter to 'df':

$ df /mnt/cdrom
File system Size Used Avail Use% Mounted on
- 641M 641M 0 100% /mnt/cdrom

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"mount: can't find /mnt/{device} in /etc/fstab or /etc/mtab"

You have tried to mount a partition or device by supplying only its mount directory. This only works for mount points listed in '/etc/fstab'. Either add it there or use the full mount line, like mount /dev/device /mnt/mount_directory.

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'{device} is not a valid blockdevice'

Either this means you have provided the wrong options to 'mount' on the command line or in '/etc/fstab', or the media hasn't been inserted or isn't formatted properly. This can also happen if the CD features an ISO9660 extension which isn't supported by your CD drive (CD Text, for example).
This message refers to the so-called major and minor numbers of devices listed in '/dev'. For example:

$ ls -l /dev/sda
brw-rw 1 root disk 8, 0 {etc}

'8' is the major number of 'sda' and '0' its minor number (so 'sdb' has 8,1). Linux handles devices by these numbers, not by their names. A list of valid names can be found in 'devices.txt' in the kernel's documentation directory. Usually you don't have to create new device nodes in /dev. If you do, and you get this error afterward, check if you've chosen the correct major and minor number for this device.

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Audio CDs Don't Play When Mounted

Audio CDs mustn't be mounted if you want to play them. If you mount them, Linux regards them as data CDs. This can lead to problems when 'supermount' is enabled. The solution is to unmount the CD (umount /mnt/cdrom) and to remount it when you want to insert a data CD. Unmounting a 'supermounted' device will disable 'supermount' for this device during the rest of the session. Or, having two CD-R drives, to disable 'supermount' on one of them at all.

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"input/output error"

This error occurs when you try to access a medium which hasn't been mounted - or, in case of supermount, inserted - yet, but might also be caused by a media failure or - with 'supermount' - by a software error.

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No Proper Unmounting ('Device Busy')

This annoying error is either due to you still being inside a directory on a medium you try to unmount (eg in an xterm) or due to some rampant or misguided process which refuses to have its contents flushed and written to the drive. Wrongly configured or malfunctioning sound daemons are justly infamous for this kind of behavior. To find out, try to unmount the partition (do this on the console, not in X) and then run (as 'root')

~# lsof /dev/device

where device is the system name of the partition which doesn't unmount properly (use df to find out). It should now show you the process(es) which are still have open files on the partition despite the unmount command.

As ML user Michael Javis knows, the reasons for this error may sometimes not be that obvious:

>

>"I had reinstalled some RPMs from my Mandrake 7.2 CDs, and after installing I was unable to unmount the CDROM drive. Every time I would try to unmount /mnt/cdrom I would get a "device busy" error, even though I had no obvious files open on the device (such as viewing a README file with 'less' for example).

>"If you are installing an RPM, directly from the CDROM, that affects the Apache web server (such as some of the PHP RPMs)...the RPM post-install script will do a restart of your web server. If your current working directory is on the /mnt/cdrom file system then the Apache web server will have open files on the device, preventing you from unmounting the CDROM.

>"I changed to my home directory and restarted my web server and was finally able to unmount /mnt/cdrom."

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No User Access To Files On Mounted Windows Partition

To allow users read access to files on a mounted Windows partition (FAT, FAT32 or NTFS), you have to add the 'mount' option

umask=0

to the according entry in '/etc/fstab' and then remount the partition. Without this option, only 'root' can access files on such partitions.

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Trouble Mounting Removable Media With Different File Systems

Generally, you can run into two sorts of trouble when mounting removable media with different file systems on them to the same mount point.

Different partition setup.. Due the different handling of partitions in Unix, Windows and Mac OS, FAT-pre formatted removable media usually use either the fourth or the fifth partition to store data, but not the first. If you reformat these media using the Linux ext2 file system, however, the first partition will become the main data partition, thus rendering the according entry in '/etc/fstab' invalid for this medium.
You will either need to create a different entry for this medium in '/etc/fstab', or take care of formatting the medium according to its original partition layout. Best bet is to not reformat the medium at all.

File system specific mount options. 'mount' offers you the possibility to specify

auto

umask

codepage

Either remove these options or create a separate fstab entry.

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Although this list of possible errors may sound disconcerting, mounting usually just works. But it can be annoying, if it doesn't ;-).

Next Item: Configuring autofs

Related Resources:

man mount

Revision / Modified: Jan. 09, 2002
Author: Tom Berger

Legal: This page is covered by the GNU Free Documentation License . Standard disclaimers of warranty apply. Copyright LSTB and Mandrakesoft.