Bug 54657

Description of Problem:

Using 7.2, I've tried setting up Software RAID using Disk Druid. This is
RAID 0 on 4 18GB SCSI disks. I've noticed that when I do this, it works,
but there is one problem that shows up if any disk partitions for separate
mount points, including swap partitions, are of the same size: the
/dev/md[x] devices ignore what RAID partitions you specify and mix and
match different partitions across cylinder boundaries. I consider this a
problem for two reasons:

(1) it is my understanding that for optimum performance that all RAID
partitions for a given RAID device should reside across the same cylinder
boundaries
(2) even if (1) isn't correct, Disk Druid should not modify which RAID
partitions should go into a selected RAID device.

FWIW, I tried to workaround the problem using Kickstart -- the problem
still occurs here -- the partitions I specify are ignored and partitions
are mixed across cylinder boundaries. This indicates an anaconda problem to me.

I realize all of this may be confusing, here is an example. Suppose I have
four disks. I create a 512 MB partition on each one for a given mount point
(say /tmp). These partitions are all on the same cylinder boundaries. I
then make the RAID device and specify that each of these partitions --
/dev/sda11, /dev/sdb11, /dev/sdc11, and /dev/sdd11 -- should be used to
make up the RAID device for /tmp. Then I create another 512 MB partition on
each of the disks for another mount point (say /var/tmp). Again, these
partitions are all on the same cylinder boundaries. I then make the RAID
device and specify that each of these partitions -- /dev/sda12, /dev/sdb12,
/dev/sdc12, and /dev/sdd12 -- should be used to make up the RAID device for
/var/tmp. If I then go and edit each of these partitions to verify the
partitions that make up each RAID device, or if I go ahead an install and
then check the /etc/raidtab afterwords, the RAID device for /tmp might be
make up of /dev/sda12, /dev/sdb11, /dev/sdc11, and /dev/sdd12 and /var/tmp
might be made up of the other 512 MB partitions, meaning that I now have
RAID devices using disk partitions crossing different cylinder boundaries.
Trying to "fix" this by restating in Disk Druid which partitions should be
used for each device does no good.

This problem also exists if swap partitions are used that are the same size
(in this example, swap partitions of 512 MB each)--swap might be on
/dev/sda10, /dev/sdb11, /dev/sdc10, and /dev/sdd10, with the RAID device
using the other partitions.

Again, installing from Kickstart also exhibits the same problem. The only
workaround is to ensure that the partition sizes for all RAID devices
including non-RAID swap partitions must be of different sizes. 

Version-Release number of selected component (if applicable):

7.2

How Reproducible:

everytime

Steps to Reproduce:
1. 
2. 
3. 

Actual Results:


Expected Results:


Additional Information: