> > Also, I wonder if there is any easy way to get the info off from my > > current 2 drive LVM onto the raid? (I would like to use > some of these > > LVM drives to be put in this raid). > > This could be tricky. I can't think of a way to do this at > the moment. If you can consolidate this data into a 1 disk LVM ... > > > Can I started with all my info on > > one HD and turn that into a Raid, or does a raid have to be > > parititoned, constructed and THEN have information copied > on to it...
Well, moving stuff around on an LVM system is trivial, as LVM supports moving physical volumes transparently. I've just been trough a disk upgrade: Old system: =========== Physical: 1x 300GB, 1x 400GB. Volume Group: Linear with both PVs. Logical: Two logical volumes (root as / and video as /var/video) New: ==== Add 3 400 GB disks and a promise 4-port SATA controller (only two sata ports on the mainboard). Finding the right way to convert to a new system is slightly tricky :-). Parameters: - want to use full capacity of all drives. - want to use raid5 to protect against data failures. - when creating a new raid5 it can be created in degraded mode, temporarily leaving out exactly one disk. - don't want to lose any data during the conversion :-) - I don't mind a system crash if a disk goes down so I'm not putting swap on raid1; - I do mind if I can't boot any longer, so /boot stuff goes on raid1 (which can be booted from, while raid5 doesn't work for boot) To make best use of the available disks, I'll need 2 Raid5 arrays: * 5x300Gb, size dictated by the 300GB disk * 4x100GB, to make use of what's left on the 400GB disks * a few 100 megs outside the raid5 since booting off raid5 is impossible. * I don't really need swap, so ~200MB swap should be enough for me. To keep setup as easy as possible, compile raid1 and raid5 right into the kernel (not as modules) and set the partition type for all raid partitions to "fd" - this way, the kernel can automatically start all the raid arrays without resorting to initrd; On the other hand if you're already using root on LVM (like I do for my system) an initrd is required anyway and raid startup can be added before starting LVM. /dev/sda => 300GB, old /dev/sbd => 400GB, old /dev/sdc, /dev/sdd, /dev/sde => 400GB, new # Partition the 3 new 400GB disks: /dev/sdc1 100MB /dev/sdc2 300GB (get size as near to the full size of the 300GB disk as possible, size must be identical or slightly larger than the existing disk) /dev/sdc3 100GB (whatever's left on the disk) Same for sdd and sde # create /dev/md0 for /boot mdadm --create --level 1 --raid-devices 2 /dev/md0 /dev/sdc1 /dev/sdd1 # create the raid for the 4 100GB chunks on the 400GB disks, leaving out /dev/sda since that's still in use in the old config mdadm --create --level 5 --raid-devices 4 /dev/md1 /dev/sdc3 /dev/sdd3 /dev/sde3 missing The last parameter "missing" tells mdadm that the array is to be created in degraded mode and that the final partition will be added at a later time. # create a physical volume on /dev/md1 pvcreate /dev/md1 # add physical volume to my Volume group vgextend MythVideo /dev/md1 Now I've got at least as much free space in my Volume group as whatever's stored on /dev/sda (the 300GB disk). In my case that's already part of the VG, so moving it is very simple: # move logical volume off /dev/sda using the space available on /dev/md1 pvmove -v /dev/sda1 /dev/md1 This will run for quite some time; at the end /dev/sda1 doesn't hold any more data. We can now remove /dev/sda1 from the VG # remove 300GB disk from the VG and remove the pv signature vgreduce MythVideo /dev/sda1 pvremove /dev/sda1 Ok, the 300GB disk is now completely unused. We can now use it to create /dev/md2 - the 5x300GB array; again, we'll have to leave out one device (the old 400GB disk /dev/sdb is still in use) mdadm --create --raid-level 5 --raid-devices 5 /dev/md2 /dev/sda1 /dev/sdc2 /dev/sdd2 /dev/sde2 missing # same procedure as before: add the new space to the Volume group and migrate the stuff stored on /dev/sdb off that disk pvcreate /dev/md2 vgextend Mythvideo /dev/md2 pvmove -v /dev/sdb1 /dev/md2 # Remove /dev/sdb1 from the Volumne group and remove the physival volume signature to completely free the disk vgreduce MythVideo /dev/sdb1 pvremove /dev/sdb1 Now we've gotten the stuff previously stored on /dev/sdb onto the new raid5. Up to now the raid's running in degraded mode, now we're going to add the final partition to actually get the redundancy we want. Repartition /dev/sbd just like the other 400GB Disks. Since the disk is no longer used repartitioning should be possible without reboot. # add final partitions to the raid5 arrays mdadm --add /dev/md1 /dev/sdb3 mdadm --add /dev/md2 /dev/sdb2 You can have a look at /dev/mdstat so see when the new partitions are completely integrated and your raid 5 devices have finished syncing. # prepare swapspace mkswap /dev/sdb1 mkswap /dev/sde1 # prepare filesystem for the new /boot directory - this needs to be off the raid5 if you already have /boot mounted on a seperate filesystem you'll obviously have to change the stuff below slightly. mkfs.ext3 -j /dev/md0 mkdir /newboot mount /dev/md0 /newboot cp -a /boot/* /newboot mv /boot /boldboot umount /newboot rmdir /newboot mv /newboot /boot mount /dev/md0 /boot Ok, we're pretty much finished. Adjust /etc/fstab to mount /boot and add swap from /dev/sdb1 and /dev/sde1. Rerun lilo if you're using that. Sorry, no idea if you need to do anything special with grub to make it deal with the changed configuration. You may want to reboot now to make sure you got the configuration of your boot manager right, but it's not actually required. Use lvextend to increase the size of the logical volume(s) you want to grow. In my case the new space goes to the video logical volume and xfs_growfs can be used to resize the filesystem to make use of the new space. Oh, and in case it's not obvious: - make sure you've got a rescue CD available that has all the device drivers you need (sata, lvm, raid) so you can get back up and running in case you break things somewhere along the way - make a backup of anything yo really don't want to lose :-) Hope this gives you some ideas for upgrading an LVM system to raid. Bye, Martin
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