On Wed, Oct 13, 2010 at 03:04:26PM -0400, Matthias Johnson wrote:
> Let me clarify further.  My raid is with my partitions.  Sda1 and sdb1 are
> ext3 partitions.  Sda2 and sdb2 are swap.  Fdisk -l shows this but also
> shows the raid md0 equaling sda1 sdb1 and md1 equaling sda2 and sdb2 and
> says it doesn't recognize these partitions.  Again my thinking is because

This is a very scary and arguably bad/broken way to do this.

Your raid partitions should be type 'linux raid autodetect', if I
recall, FD.

So the way this is supposed to be set up:

disk 1:
  MBR
  Partition map
  Raid partition 1.1
  Raid partition 2.1

disk 2:
  MBR
  Partition map
  Raid partition 1.2
  Raid partition 2.2

md0 {raid 1.1, raid 1.2}
  Ext3

md1 {raid 1.2, raid 2.2}
  Swap

The reason it's scary and bad in your setup is because your raid
component partitions are marked as data, not raid.  This means
automount, human error, etc, would make it VERY easy to screw up and
start addressing one of the raid component drives, not the raid itself,
corrupting the whole thing and making your raid go ':('  "everything"
(for some reasonable value of everything) should know to not touch a
raid partition disk, or at least, throw a bunch of warnings at you.

In the above, notice that the partition type is kept in the partition
map of the parent drive, NOT in the raid data.  Your mdX virtual disks
will contain the ext3 headers and mount normally.

> md? exist as virtual devices in dev fdisk tries to determine the partition
> type and fails but can read the individual partitions on the real disks
> themselves sd?.  Just a guess.

You don't typically partition a raid, although you can.  It may
require extra tweaking in your devfs scripts to get them to show up.

-m


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