[CLUE-Tech] RAID 1 on Linux

[Carl Schelin]

Ok, question on RAIDing an existing linux system.

A little background first. I'm mainly a Solaris guy.
I've installed RAIDs on Sun boxes many times. The
procedure is simple. Create the raid using the
existing slices and add the new slices to the new
raid. They syncronize and it's working.

In a misguided attempt, and because I didn't see the
RAID option the previous times I've installed Mandrake
(under the expert menu), I installed Mandrake 9.1 on
an 80 gig seagate.

After futzing around with mdadm and raidtools, the
second disk was so fscked up, I had to use dd to fix
it (I dd'd the good hda over hdc). Finally I was able
to do a fresh install and found the RAID options under
the expert menu.

All of the documentation I've seen appear to show that
the only way to make an existing system in to RAID 1,
is to back it off, install to RAID and restore the
data.

Does anyone have a pointer to a document that debunks
this? Can I in fact, add a second disk and make the
system RAID 1 or do I have to back it off and
reinstall?

Just so you know, I've read the Managing RAID on LINUX
book (three years out of date), the Software Raid
HOWTO over at unthought, the Quick Software RAID over
at linuxhomenetworking, the kernel raid list (just
poking around in the archives) and even the various
man pages for mdadm and mkraid.

Of course if it's in one of these documents, please
point me at the right section.

Thanks for any pointers.

Carl


		
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