FirstServed Tech Blog - FirstServed and the Art of Server Tuning

Use this command to read the BIOS dmi data in linux:
dmidecode

Reads mainboard type, bios version, memory banks, …

Limit dom0 to fixed size of memory.
Don’t use up all system memory.
Otherwise dom0 will suffocate the xen net driver.
Which causes loss of network connectivity for some guests.

SNMPD has problems with xen net drivers.
Why?
Xen net emulates a blank MAC address (FF:FF:FF:FF:FF:FF)
Which in it’s turn generates a faulty IPv6 address which is duplicated amongst the interfaces.
SNMPD cannot handle these duplicated addresses an detects an IP conflict.

Our Mailservers use a separate disk to store the mailboxes.
These are mounted on a folder, but most commonly used via a symbolic link that points to this folder.

This is where bacula gets stuck.
It creates the symbolic link, which is invalid due to the temporaty restore location and then crashes because it cannot create the files and directories.

To solve this, manually create the symbolic link location, but do not create it as a link, create it as a folder.
This is probably a miss-configuration on our side, but it might be a problem nontheless.

Example:
Mail location: /var/spool/mail
Link: /var/mail
Bacula backs up: /var/mail
Manually create /tmp/bacula-restores/var/mail/ to have a successfull restore.