[CentOS-docs] Software RAID on CentOS 5 ... ideas ...

Thu Aug 13 22:55:00 UTC 2009
Clinton Lee Taylor <clintonlee.taylor at gmail.com>

Greetings ...

 Been lurking on the list for some time, hoping that at some point, I
might be able to add to the collective (Yes, way to much StarTrek in
the background! ) ...

 I have learn quite a bit by just lurking, but now I think I might
have something to add ... I'm not sure the exact protocol or procedure
for this and it's late in the evening and would like get this out,
before I forgot or lose my cool ... Sorry ...

 First, in SoftwareRAIDonCentOS5, I would like to suggest a third
option, to updating or running grub ... My motivation for a third
option, is that hand typing or coping and paste line for line into
grub, could lead to cross-eyed mistakes ... So, a simple copy and
pasting of the complete bash mini script, would be a little less error
prone ... as follows ...

grub --no-floppy <<EOF
device (hd0) /dev/sdb
device (hd1) /dev/sda
root (hd0,0)
setup (hd0)
device (hd0) /dev/sda
device (hd1) /dev/sdb
root (hd0,0)
setup (hd0)

 One other suggest, devices removed from older raid setup, might need
the metadata remove, with the following ... This gave me hell for many
days ...

mdadm --zero-superblock /dev/sdc1
mdadm --zero-superblock /dev/sdc

 The last suggestion I have, is to do with copying the partition
layout from one device to another ...
First in single steps ... Can also be used as a backup of the
partition layout for later use ...

sfdisk -d /dev/sda > sda.out
to dump the partition layout ...
sfdisk /dev/sdb < sda.out

Or in a single step ...
sfdisk -d /dev/sda | sfdisk /dev/sdb

I can't remember where I got all these details, so I can really give
credit where it's due, this is just info that I have collected over
time ... I hope this is useful.


P.S. I have been toying with an alternate procedure for converting an
ext3 partition on a block device to an ext3 partition on a RAID1
device ... If anybody interested before linux-raid comes back to me,
just let me know and I will forward what I have been working on.