On Sun, 2005-02-06 at 23:16 +0100, Remy Blank wrote: > Nick Smith wrote: > > also, what about a mirrored raid? is it possible to create one > > without having to start from scratch and reinstall? like just add the > > drive to mirror to and mirror it? what would be the best solution for my > > situation? > > The advantage of RAID is that you have an always-up-to-date copy of your > disk. You can transfer your existing install to a RAID configuration, > but it involves doing a full file-by-file copy. The procedure goes along > the following: > > - Perform a backup of your important data. Just in case. > - Do an orderly shutdown of your system. > - Install your new hard drive. Put it on another channel than the first > drive (for example, if your first hard drive is hda, install the new > drive on the second channel, as either hdc or hdd). The following > assumes it is hdc. > - Boot from a liveCD (e.g. Knoppix). > - Insert the raid1 module: > # insmod raid1 > - Partition your new disk to have approximately the same layout as the > old one. Set the partition type to fd (Raid autodetect): > # fdisk /dev/hdc > - Create new (degraded) md devices for every partition, with two > devices, one being a partition of your new disk, and the other one > marked as missing: > # mdadm --create /dev/md0 -l 1 -n 2 /dev/hdc1 missing > # mdadm --create /dev/md1 -l 1 -n 2 /dev/hdc2 missing > ... > - Create filesystems on the new md devices, for example ext3 or swap: > # mke2fs -j /dev/md0 > # mkswap /dev/md1 > ... > - Mount both the old disk and the new md devices, and copy the content > of all partitions from the old disk to the new one: > # rsync -avH /mnt/hda1/ /mnt/md0 > ... > - Edit a few strategic files (fstab, lilo.conf or grub.conf, etc) on the > md devices to reflect that your new root filesystem is on /dev/md? > instead of /dev/hda? > - Do a poweroff. > - Swap both hard drives. From now on, your old disk is /dev/hdc and your > new disk is /dev/hda. > - Re-boot into the liveCD, re-insert the raid1 module, re-mount your md > devices. > - If you use lilo, re-run it on the md device: > # lilo -r /dev/md0 > - Reboot, but without the liveCD, this time. You should boot into the > same system as before you started, except it is now running from a > degraded RAID1. > - Check that *everything* works as expected. Do a real *thorough* test, > because the next steps will wipe all the data on your old disk. > - Partition the *old* disk to have the same layout as your new disk. If > the partition sizes don't match exactly, create them slightly bigger > than on your new disk. Also set the partition type to fd. > - Hot-add the partitions from your old disk to the degraded RAID devices: > # mdadm /dev/md0 -a /dev/hdc > - Re-run lilo if that's your bootloader. > - You can watch the reconstruction process with: > # watch -n 10 cat /proc/mdstat > - Et voil�! Your existing install has been tranfered to a RAID1 system. > > I have performed this operation several times, and it works like a > charm. Note that this is all from memory, so I might have missed a few > points. I would suggest you only embark on such a procedure if you fully > understand what happens at every step, and are prepared to improvise in > case I have missed something. > > HTH. > -- Remy > > > Remove underscore and suffix in reply address for a timely response. > > i have setup RAID5's before in linux a couple years ago, so i know about what your talking, but again from memory im a little fuzzy, at least i know it can be done now without a fresh install. i will try this when i get time.
thanks -- [email protected] mailing list
