It seems that I wasn't the first one to have idea of sharing MySQL installation between OpenVZ containers. However, simple hardlink didn't work for me:
root@koha-hw:~# ln /vz/root/212052/var/run/mysqld/mysqld.sock \
/vz/root/212056/var/run/mysqld/
ln: creating hard link `/vz/root/212056/var/run/mysqld/mysqld.sock' to
`/vz/root/212052/var/run/mysqld/mysqld.sock': Invalid cross-device link
So I tried something a little bit different:
root@koha-hw:~# mount --bind /vz/root/212052/var/run/mysqld/ \
/vz/root/212056/var/run/mysqld/
Which worked for me on old etch Debian kernel:
root@koha-hw:~# uname -a Linux koha-hw 2.6.18-openvz-18-53.5d1-amd64 #1 SMP Sat Mar 22 23:58:13 MSK 2008 x86_64 GNU/LinuxI have wrong permissions, but socket is world-writable anyway... There is also related bug for kernels 2.6.24 and 2.6.26.
