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Protecting your SAN LUNs during installation

When you're installing a new ESX host, it's important to take precautions to make sure that you're not overwriting a SAN LUN where your precious VMs reside. To keep those LUNs safe, you have a few options which I'm going to list from most cautious to least cautious.

Physically disconnect the fibre that runs into the server

Unpresent the LUNs from the ESX host through zoning on your SP/Switches

Remove the drivers from the installation media ( check out this script if you're interested )

Run a script in %pre of the kickstart which unloads all of the fibre kernel modules ( Emulex and Qlogic ) so that you can't inadvertently install onto a SAN LUN. The following script was originally posted on VMTN by user timmp. You need to inject this script into the %pre section of your kickstart.

%pre

#!/bin/sh

# This will remove the loaded HBA modules from the kernel
remove_qla(){
for i in $(lsmod | grep qla | awk '{print $1'}); do
 echo Will remove: $i >> /dev/tty1
rmmod $i
sleep 1
done
}

remove_lpfc(){
for i in $(lsmod | grep lpfc | awk '{print $1'}); do
 echo Will remove: $i >> /dev/tty1
rmmod $i
sleep 1
done
}

remove_qla
sleep 2
remove_qla
remove_lpfc

Use the --ignoredisk options to mask your LUNs during installation


ignoredisk –-drives=sda,sdb,sdc,sdd,sde,sdf,sdg,sdh,sdi,sdj,sdk,etc,etc

If you're using Compaq/HP gear, the scsi devices are named differently, and if you specify them explicitly you *should* be safe.


# Bootloader options
bootloader –location=mbr –driveorder=cciss/c0d0
# Disk Partitioning
clearpart --all --initlabel --drives=cciss/c0d0
part /boot      --fstype ext3    --size 250   --ondisk cciss/c0d0  --asprimary
part /          --fstype ext3    --size 5192  --ondisk cciss/c0d0  --asprimary
part swap       --fstype swap    --size 1600  --ondisk cciss/c0d0  --asprimary
part /var/log   --fstype ext3    --size 4096  --ondisk cciss/c0d0
part /tmp       --fstype ext3    --size 4096  --ondisk cciss/c0d0
part /home      --fstype ext3    --size 2048  --ondisk cciss/c0d0
part None       --fstype vmfs3   --size 8192  --ondisk cciss/c0d0  --grow
part None       --fstype vmkcore --size 100   --ondisk cciss/c0d0

You can use one or more of those options to keep your data safe while you install/upgrade your ESX hosts. If you inadvertenly destroy a VMFS volume, it's extremely hard to recover that data.

Labels: emulex qlogic kickstart san lun installation

Posted by Dominic Rivera at Friday, June 19, 2009.

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Protecting your SAN LUNs during installation

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