RAID Munging Question

Kent Borg kentborg at borg.org
Fri Apr 5 12:19:07 EST 2002


I recently got a new box up and running Red Hat 7.2.  What's more, I
put in two 60 GB disks in software RAID 1 so that if one dies the
other should keep running (even swapping because swap has its own RAID
1 partition).  Either disk should be bootable, too.  How fun!

Except I have a problem.  When doing some timings with hdparm I
noticed one partition was significantly faster than the others.
Casting about further I discovered I made a mistake.  Apparently when
I punched the "Make RAID" button in the Red Hat installer I forgot to
select "RAID 1" from the menu that defaults to "RAID 0".

My /home partition is RAID 0 (no redundancy, but bigger and faster)
instead of RAID 1 (redundancy, smaller, somewhat faster read than raw
disk). 

Does anyone know how to fix this?


Here is my current best guess:

  1. Reboot single user (so little will being going on)

  2. Tar up /home and park it in another partition--luckily I do have
     the room,

  3. Edit /etc/raidtab so /dev/md5 line that currently reads
     "raid-level 0" will read "raid-level 1",

  4. "# unmount /home"

  5. "# mkraid /dev/md5",

  6. "# mkfs /dev/md5",

  7. Wait for mkfs to finish,

  8. "# mount /dev/md5 /home",

  9. See if df sees right size disk,

 10. Disconnect internet connection (don't want any new e-mail yet),

 11. Reboot regularly, things working?,

 12. Plug in internet connection.


Do you people think it will work?  Will it work?


Thanks,

-kb, the Kent who doesn't want a dead-in-the-water machine or /home.



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