Running an apt-get update or an apt-get install occasionally times out on VMs that I am building before I have setup IPv6. Instead of waiting the (seemingly) long time for it to timeout, just add:
to the end of the apt-get command to force IPv4.
And to make it permanent:
create /etc/apt/apt.conf.d/99force-ipv4 and put in it:
When adding a disk back to an mdadm array I got this error for the md0 array which was actually my swap partition.
root@mothership2 ~ # mdadm --manage /dev/md0 --add /dev/sdb1
mdadm: Cannot get array info for /dev/md0
To fix this you have to run:
mdadm --stop /dev/md0
mdadm --assemble --scan
Then you can add the drive to array like so:
mdadm --manage /dev/md0 --add /dev/sdb1
mdadm: added /dev/sdb1
You have new mail in /var/mail/root