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thiesdiggity
Asked: 2011-10-13 20:30:31 +0800 CST

How to remove swap partitions from RAID 1 Array on Ubuntu?

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Can anyone point in the right direction on how to remove SWAP out of a RAID1 configuration on Ubuntu 10.04 server? According to the Ubuntu Advanced installation guide, here, it said to add swap to the raid but I am having some serious performance issues. I would like to remove it from the array and recreate it, with the same size, on the two separate drives. Zero data loss on the other array is a must.

Its a remote computer so I would prefer to do it via command-line if possible.

Here is the output from cat /proc/mdstat

md0 : active raid1 sdb1[1] sda1[0]
19530688 blocks [2/2] [UU]

md1 : active raid1 sdb2[1] sda2[0]
957230016 blocks [2/2] [UU]

Swap is on the md0 device.

Thanks

performance software-raid formatting raid1 ubuntu-10.04

2 Answers

  1. Best Answer

    Assuming you've got swap on /dev/md1, this should work (this is in a root prompt):

    # mdadm /dev/md1 --fail /dev/sdb2
# mdadm /dev/md1 --remove /dev/sdb2
# mdadm --zero-superblock /dev/sdb2
# mkswap /dev/sdb2
# echo "/dev/sdb2 none swap sw 0 0" >> /etc/fstab
# swapon /dev/sdb2
# swapoff /dev/md1
# mdadm --stop /dev/md1
# mdadm --zero-superblock /dev/sda2
# mkswap /dev/sda2
# echo "/dev/sda2 none swap sw 0 0" >> /etc/fstab
# swapon /dev/sda2

    If you use sudo for these (as you probably should), you'll need to change echo $foo >> $blah to echo $foo | sudo tee -a $blah$.

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  2. Meanwhile it depends on the version of kernel you use, LSR RAID-1 can give performance boost when reading from it — due to possible read balancing. Also, making swap not using RAID-1 means you have unstable OS (app hangs/crash) when one of the disks has failed. In other words, it's rather senseless idea.

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