barthalamu
asked on
Mirror existing system disk
I have a CentOS 5 machine set up with LVM2 set up on the first disk /dev/sda. The other disk is /dev/sdb. They are idential disks and I would like to mirror them but have not been able to do so. It must be possible to mirror /dev/sda to /dev/sdb even though it has already been partitioned and is in use, but I have not been able to figure out how. The disks look like this:
fdisk -l
Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 30401 244091610 8e Linux LVM
Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 13 104391 83 Linux
/dev/sdb2 14 30401 244091610 8e Linux LVM
When I try to mirror the first partition, I get the following:
mdadm --create /dev/md0 --level=1 --chunk=1024 --raid-devices=2 /dev/sda1 /dev/sdb1
mdadm: Cannot open /dev/sda1: Device or resource busy
mdadm: create aborted
Do I need to boot to a CD distribution like knoppix to do this? Thanks for any help you can give me.
fdisk -l
Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 30401 244091610 8e Linux LVM
Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 13 104391 83 Linux
/dev/sdb2 14 30401 244091610 8e Linux LVM
When I try to mirror the first partition, I get the following:
mdadm --create /dev/md0 --level=1 --chunk=1024 --raid-devices=2 /dev/sda1 /dev/sdb1
mdadm: Cannot open /dev/sda1: Device or resource busy
mdadm: create aborted
Do I need to boot to a CD distribution like knoppix to do this? Thanks for any help you can give me.
PUNKY
http://www.flmnh.ufl.edu/linux/linux_software_raid.htm
Look at this tutorial. It's for novel, but works for any Linux OS.
http://www.novell.com/coolsolutions/appnote/15087.html
http://www.novell.com/coolsolutions/appnote/15087.html
ASKER
Thank you both.
PUNKY - Although this would work during installation, I already have a system installed. I just need to make a RAID1 out of my existing boot/system disk.
ravenpl - This is very interesting, but it does not look like it is for LVM on RAID. I suspect that it will probably not work, although I'm not sure. I can seem to find the information of how to create a RAID1 mirror when I already have a system installed on /dev/sda using LVM.
PUNKY - Although this would work during installation, I already have a system installed. I just need to make a RAID1 out of my existing boot/system disk.
ravenpl - This is very interesting, but it does not look like it is for LVM on RAID. I suspect that it will probably not work, although I'm not sure. I can seem to find the information of how to create a RAID1 mirror when I already have a system installed on /dev/sda using LVM.
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ASKER
Thanks ravenpl. I think I can make this work with LVM instead of regular partitions. Thanks.