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Troubleshooting (Ubuntu) (view source)
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= Network = | '''For performance problems related load, see [[High_System_Load_(Ubuntu)|High System Load]]''' | ||
== No NIC == | |||
== Network == | |||
=== No NIC === | |||
Especially after hardware changes, its possible the networking config no longer refers to the right interface. | Especially after hardware changes, its possible the networking config no longer refers to the right interface. | ||
| Line 6: | Line 8: | ||
# Use <code> dmesg | grep -i eth </code> to ascertain what's been detected at boot time | # Use <code> dmesg | grep -i eth </code> to ascertain what's been detected at boot time | ||
# Assuming it states that say <code>eth0</code> has been changed to <code>eth1</code> then just update the <code>/etc/network/interfaces</code> file | # Assuming it states that say <code>eth0</code> has been changed to <code>eth1</code> then just update the <code>/etc/network/interfaces</code> file | ||
# Alternatively, force the ''new'' NIC to be <code>eth0</code> by editing the <code>/etc/udev/rules.d/70-persistent-net.rules</code> file | |||
#* You'll need to reboot the server for changes to take effect | |||
== File System == | |||
=== Unable to Mount CD-ROM === | |||
Mounting drive with following command fails | |||
* <code> mount /dev/cdrom /media/cdrom/ </code> | |||
If <code>/media/cdrom/</code> doesn't exist | |||
# Create the file with <code>mkdir /media/cdrom</code> | |||
If <code>/dev/cdrom</code> special device doesn't exist | |||
# Check for existing mappings and devices | |||
#* <code>ls -l /dev/ | grep cdrom</code> | |||
# If an existing mapping exists but for a different drive number (eg <code>cdrom2 -> sr0</code>) | |||
#* Then try mounting with that number | |||
#* EG <code> mount /dev/cdrom2 /media/cdrom/ </code> | |||
# If no existing mapping exists | |||
#* Then try creating one for one of the listed devices | |||
#* EG <code> ln -sf /dev/sg0 /dev/cdrom </code> | |||
= | === Replacing a Software RAID 1 Disk === | ||
== Replacing a RAID 1 Disk == | |||
This procedure was written from the following starting point... | This procedure was written from the following starting point... | ||
* A machine originally with two disks in RAID1 has failed, one disk has been replaced, and machine started again | * A machine originally with two disks in RAID1 has failed, one disk has been replaced, and machine started again | ||
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#* <code> more /proc/mdstat </code> | #* <code> more /proc/mdstat </code> | ||
= SSH = | === Recover Deleted Files === | ||
== Server Hostname Change == | Ideally you should recover files to a seperate disk partition to the one you are attempting to recover from. This procedure should help to recover lost or corrupted files from a filesystem using [http://manpages.ubuntu.com/manpages/lucid/man1/scalpel.1.html Scalpel], a data recovery utility built on the foundation of [http://foremost.sourceforge.net/ Foremost] | ||
# Install Scalpel | |||
#* <code> apt-get install scalpel </code> | |||
# Update the config file to search for the lost files (uncomment/add as neccessary) | |||
#* <code> /etc/scalpel/scalpel.conf </code> | |||
#* For PHP files (not embedded in HTML) use <code> php n 50000 <?php ?> </code> | |||
# Create a folder for the recovered files to go to | |||
#* <code> mkdir /tmp/recov </code> | |||
# Launch Scalpel to trawl the disk image (will takes ages, and source disk will be under high load) | |||
#* <code> scalpel /dev/mapper/svr-root -o /tmp/recov/ </code> | |||
# Search through recovered files to find the data of interest | |||
#* <code> grep -R "string you want to find" /tmp/recov/* </code> | |||
== SSH == | |||
=== Server Hostname Change === | |||
If the hostname (or IP) of the server you are SSH'ing to changes, the old entry needs to be removed from your SSH key known hosts file | If the hostname (or IP) of the server you are SSH'ing to changes, the old entry needs to be removed from your SSH key known hosts file | ||
* <code> ssh-keygen -R <name or IP> </code> | * <code> ssh-keygen -R <name or IP> </code> | ||
= Packages = | == Packages == | ||
Errors etc received from <code>apt-get</code> | Errors etc received from <code>apt-get</code> | ||
* '''Error 400 Bad Request''' | * '''Error 400 Bad Request''' | ||
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** Package manager can hold back updates because they will cause conflicts, or sometimes because they're major kernel updates. Running <code>aptitude safe-upgrade</code> normally seems to force kernel updates through. | ** Package manager can hold back updates because they will cause conflicts, or sometimes because they're major kernel updates. Running <code>aptitude safe-upgrade</code> normally seems to force kernel updates through. | ||
= Reboot Required? = | === Add EOL Repository === | ||
Once a version of Ubuntu has gone End Of Line (EOL), you can't install software packages using the normal repository. On trying you'll get an error similar to | |||
* <code>Failed to fetch http://gb.archive.ubuntu.com/ubuntu/pool/main/s/<package> 404 Not Found</code> | |||
The repository is still available, but via a different URL - http://old-releases.ubuntu.com | |||
Edit <code>/etc/apt/sources.list</code> and add the following (replace hardy with your flavour of Ubuntu). Remove the existing ubuntu repositories (they'll just cause errors as they're inaccessible) | |||
<pre> | |||
# Hardy EOL | |||
# Required | |||
deb http://old-releases.ubuntu.com/ubuntu/ hardy main restricted universe multiverse | |||
deb http://old-releases.ubuntu.com/ubuntu/ hardy-updates main restricted universe multiverse | |||
deb http://old-releases.ubuntu.com/ubuntu/ hardy-security main restricted universe multiverse | |||
# Optional | |||
#deb http://old-releases.ubuntu.com/ubuntu/ hardy-backports main restricted universe multiverse | |||
</pre> | |||
== Reboot Required? == | |||
If a package update/installation requires a reboot to complete the following file will exist... | If a package update/installation requires a reboot to complete the following file will exist... | ||
/var/run/reboot-required | /var/run/reboot-required | ||
| Line 44: | Line 98: | ||
To see which packages caused this to be set, inspect the contents of... | To see which packages caused this to be set, inspect the contents of... | ||
/var/run/reboot-required.pkgs | /var/run/reboot-required.pkgs | ||
== Firewall == | |||
=== ERROR: problem running ufw-init === | |||
If on starting or reloading <code>ufw</code> you receive this error, its likely that you have a configuration problem. This is especially likely if you've needed to edit <code>ufw</code>'s config files directly. | |||
# Ensure that <code>ufw</code> is running | |||
#* <code> ufw enable </code> | |||
# Force the config to be reloaded | |||
#* <code> /lib/ufw/ufw-init force-reload </code> | |||
# Or if <code>ufw</code> failed to start use | |||
#* <code> /lib/ufw/ufw-init start </code> | |||
Doing the above should trigger the error, and present a better description of what the problem is | |||
See http://ubuntuforums.org/showthread.php?t=1660916 for further info | |||
[[Category:Ubuntu]] | [[Category:Ubuntu]] | ||
[[Category:Troubleshooting]] | [[Category:Troubleshooting]] | ||
[[Category:Bash]] | |||