I have 2 harddisks, sda and sdb.

/dev/md0 consists of sda2 and sdb2, mounted as /

I have created /dev/md1 consisting of two swap partitions, /dev/sda1 and /dev/sdb1, with the following:

# mdadm --create /dev/md1 -l1 -n2 -x0 /dev/sda1 /dev/sdb1
# mkswap /dev/md1

Then I edit /etc/fstab to add the following:

/dev/md1 none swap sw 0 0

# swapon -a

Following which, I edit the /etc/mdadm/mdadm.conf with

# rm /etc/mdadm/mdadm.conf
# mdadm --detail --scan > /etc/mdadm/mdadm.conf
# MAILADDR root >> /etc/mdadm/mdadm.conf

After I reboot, the swap (/dev/md1) is active. However, if I unplug one of the disk (sda) to test if the RAID works, the system still boot (I've installed GRUB on the both harddisks), but the swap (/dev/md1) is not active.

How should I go about enabling /dev/md1 to activate on boot when one of the disk is unplugged?

Thanks !

I could be wrong when I say this but I am not sure that the swap works like that.

In my original post, I'm trying to configure the swap such that if one of the disks fail, the remaining disk will have a swap to work with.

If that is not the way it should be configured, please advise.

Thanks, much appreciated.

I was wrong. Check out this website and tell me if this is what your trying to do. Apparently you have to tell /etc/fstab to use the swap on another driver.

That is a very good link.

Thank you.

I found that very useful. I started to read and was thinging to myself, I may do something like this on my new workstation I am building. So I decided to bookmark.

It seems that the website advises using RAID for Swap for high availability. Back to my first post, how should I go about enabling /dev/md1 to activate on boot when one of the disk is unplugged?

Nevertheless, it is a good link. Thanks.

don't know how. When I get it working I will post the information. It may require some kind of script to check drive avaliablity. If it is then use this one for swap. If not then use this drive. That is what I was sort of thinking in terms of how I would write the script.

If /dev/md1 is still there after disconnecting the drive, swap should use it. Simple as that I would have thought.
What does dmesg show after the reboot ???.
Does swapon after the reboot work ???.

(Note, no experience of RAID,just concepts on my behalf)