Re: Migrating to a RAID 1 setup (hardware RAID)

AZ Nomad wrote:
On Sun, 23 Apr 2006 21:03:40 -0400, John-Paul Stewart <jpstewart@xxxxxxxxxxxxxxxx> wrote:



AZ Nomad wrote:

On Sun, 23 Apr 2006 13:41:58 -0400, John-Paul Stewart <jpstewart@xxxxxxxxxxxxxxxx> wrote:




Doug.Baggett@xxxxxxxxx wrote:


I have a Slackware 10.2 system (but this question really apples to any
distribution).

I picked up a used 3ware 7500-4LP RAID card and would like to use it
with my current LINUX system which is currently configured on a 30GB
drive.

What is the proper way to migrate the system?


The easiest is to buy two identical disks for your RAID-1 array, create the array using 3ware's configuration methods, and then copy your existing stuff over to the array using 'cp -a' or 'tar' or 'rsync' or whatever method you prefer. Then edit /etc/lilo.conf (or grub's configuration file, if that's what you use) to point to the array and re-run LILO. Shutdown, remove the old hard drive, and then boot from the new array.


Have you ever actually tried that? You do NOT use the file system to
mirror a drive!


I didn't say to use the filesystem to mirror it. I said to "create the array" and "then copy your existing stuff over" (instead of having to re-install everything).



'cp -a', 'tar', 'rsync' all use the file system. They will all create
nonidentical mirrors which will be destroyed the first time the
raid s/w or h/w writes the same sectors from the nonidentical first
drive.

Once again: I have suggested the OP create the array on two new disks using the array manufacturers utilities and copy his existing stuff to the *array* (not to one of the array component drives, but to the mirror set), treating the (whole) array as any other hard drive.

Let's put it this way: his existing hard drive should be /dev/hda. He would create an array using 3ware's configuration utilities that will then be seen as /dev/sda. The individual component disks will *not* be accesible behind a 3ware controller, /dev/sda is the pair of mirrored disks in the RAID-1 array. I have simply suggested that he can copy (partition by partition, filesystem by filesystem) the contents of /dev/hda to /dev/sda where the 3ware controller will handle the mirroring to the two component disks of the array at /dev/sda. After that's done, I've told him to *remove the old hard drive* since it won't be part of the array.

I don't understand where you get the impression that I'm saying that cp, tar, or rsync will create the mirror. I have simply said they are the way to copy an exsting drive to a RAID array. How would *you* propose he copy his existing data and configuration files to the RAID array, given the OP said he wants to avoid having to do a fresh install? The *only* way is to copy filesystems from the old hard drive to the RAID set.
.

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