Software RAID on Fedora Core 3

On FC3 you will find that raidtools has disappeared to be replaced by mdadm. The manpage is pretty helpful, but basically instead of creating a /etc/raidtab you just need to run a command like this:

/sbin/mdadm --assemble /dev/md0 level=raid1 num-devices=2 /dev/sda /dev/sdb

Which assembles a pre-existing RAID1 on /dev/sda and /dev/sdb onto /dev/md0.

The raw RAID structure of mdadm is identical to raidtools so you don't need to pre-build an existing array, if you do then you should investigtae the "--create" option of mdadm I guess.

Once the RAID has been assembled do:

/sbin/mdadm --detail --scan >/etc/mdadm.conf

There is some stuff about needing persistent superblock which still seems to need /etc/raidtab, so if the system disk is RAIDed then keep the old /etc/raidtab around (or make sure you can re-create it) otherwise you may find that when the machine reboots it won't see the system disk properly (fsck complains I think).

Creating an Array From Scratch

On Mandy -

[mandy]root: /sbin/mdadm -C -v -l 1 -n 2 -x 0 /dev/md0 /dev/hda3 /dev/hdc3

[mandy]root: /sbin/mdadm --detail --scan

ARRAY /dev/md0 level=raid1 num-devices=2 UUID=f59b92bb:4903c4bc:0f110048:8946d93f devices=/dev/hda3,/dev/hdc3

Useful web links:

• http://fedoranews.org/blog/?p=688
• plus a better one I can't remember, try google with "mdadm raidtools fc3"

-- TimColles - 16 Dec 2005