Hai ,
Plz have look and suggest something with your comments

1)
Server failed to come back after we reboot the machine.
Attached is the error message we got from the machine:-
Kernel Panic : Unable to mount root fs on (08, 00)
Fyi, version is SLES-8
We are using xSeries 345 connected to EMC CX600 for external disk array.

1. Does this always happen when adding a new drive or randomly?
2. We do have a lot of drive adding activities here. Is there a fix-around solution to prevent the new drive from taking over the position of the root partition?
/etc/sysconfig/kernel follows
#
# This variable contains the list of modules to be added to the initial
# ramdisk by calling the script "mk_initrd"
# (like drivers for scsi-controllers, for lvm or reiserfs)
#
INITRD_MODULES="scsi_mod sd_mod cdrom ide-cd mptbase mptscsih qla2300 jbd ext3"

#
# Size parameter for mounting the shmfs filesystem. The kernel defaults
# to 50% of the available RAM size, but this might not be enough for
# some special setups.
#
SHMFS_SIZE=""

--------------------
2)
Tried to add disk from SAN storage to server , we are not able to add the disk and after vgscan lost all the existing disk from SAN and we reboot the M/c. the root file system /dev/sda6 became in read only mode. we have restged the M/c now but would like to know there have been any similar problems and solutions for the same.
DEV#: 4 DEVICE NAME: vpathai TYPE: 2145 POLICY: Optimized Sequential
SERIAL: 6005076801918122d0000000000000cc
============================================================================
Path# Adapter/Hard Disk State Mode Select Errors
0 Host3Channel0/sdcw CLOSE NORMAL 0 0
1 Host3Channel0/sdbx CLOSE NORMAL 133 0
2 Host2Channel0/sday CLOSE NORMAL 0 0
3 Host2Channel0/sdz CLOSE NORMAL 120 0

We have used the Rescue CD and that did not work , we had to rebuild the whole M/c and if i connect to the same SAN and LUNs and if i issue any of the lvmconnands and if i reboot M/c root filesystem will go into read only mode.

3)
We have a problem with a couple of 445 servers. All of them has 40Gb of memory and when oracle creates large databases and the memory usaage is more than 32Gb the server hangs. I have tested that this is not an oracle error. I just did a dd on /dev/zero to a 50Gb large file. If we have 32Gb of memory the dd is working. If i use 40Gb of memory the server stops responding when there is approx. 8,5 Gb left.

confirmed the order of RAM and also confirm that BIOS is updated properly

4) can this following be added to the /etc/modprobe.conf by default ? The absense of these lines is causing sginfo to seg fault.

install paride /bin/true
install pt /bin/true
install ide_tape /bin/true

Why does this look like it was cut and pasted from a homework assignment???

This aside, Please post one question at a time. Not everyone here is going to wade thru the whole long post a try to figure out what is happening---and whether the various questions are related. In this case, the questions do NOT appear to be related.

Amazing that you are running SLES, Oracle and an IBM Server with an EMC SAN yet don't have support contracts on any of it...

All I can say is WOW !! If that were my environment I would have support contracts on all that high end equipment and I'd have Support on the phone till they fixed my problems if I didn't know the answers..

Good luck.