From: James J. Perry (jjperry@water.com)
Date: Mon Jun 12 2006 - 11:56:18 EDT
<standard_disclaimer>
Have not booted over SAN but looked into it.
</standard_disclaimer>
We did not do SAN but did boot from EMC on SCSI for K-Class servers. Pretty much technologically the same, but FC is just newer hardware.
Advantages 1: Easy same-class server migration / emergency repair.
When we relocated buildings we were able to connect any server that had the same hardware port configurations to the SCSI and boot the server. Thus with my Production on a K-580, I was able to test the migrated data on a K-360, with SCSI cards in the same hardware slots, and boot the server from the new disk array. Since most factory configurations from HP and expansions by HP follow a specific pattern, then most hardware is interchangeable in classes. Have to watch between major machine classes though.
Advantage 2: Disk array handles disk protection:
This reduces overhead on the server to handle mirror UX tasks for internal boot disks and JBOD storage. It also helps with the FC port to fault tolerance issue. If there is a port shortage, less important servers can be reduced to 1-port versus the standard 2-port connectivity for fault tolerant environments. The downside is that a failure on that port will cause the server to crash and possible data corruption.
Disadvantage 1: Multiple points of failure:
If the switch or disk array has a problem, the server will mostly likely hang if not outright crash. At that point it will not only be unable to boot until problem is resolved, but can also corrupt data.
Disadvantage 2: Multiple Vendors
When troubleshooting a server which will not boot, coordination between vendors will often result in finger-pointing. You will have to con-call all parties to get issues resolved.
Disadvantage 3: Inability to remove replaced storage arrays.
This has been the case many times. A new disk array is purchased, but it only supports certain connection methods and/or boot types. As a result the legacy environments are unable to utilize the new array. This has happened with High Voltage Differential SCSI as well as FC Loop. I know that some of the newer high-end disk arrays will only support FC Fabric signons, not loop. No new arrays support HV Diff SCSI any longer.
Again I have not booted over SAN, but I do know that on our new disk array from EMC they specifically asked if we were booting from the array. I believe they have specific director setups that must be performed to allow it to boot.
Any SAN switch should allow servers to boot. I have not seen a real difference between Brocade or McData. Whichever model you choose, you will need to decide costs. I know that older HP servers only had FC Loop availability and most disk arrays are FC Fabric / Hyper Fabric only. Thus you might not be able to connect the D-Class or E-Class to a newer disk array. Also the switch may not support FCAL connectivity. Many switches will also not allow mixed FCAL and FC Fabric.
Generally I prefer to have OS on internal storage and all other be external. While you can extend your server's life with external storage, you get hit eventually with not being able to connect to the storage any longer as it updates.
-Jim
________________________________
From: hpux-admin-owner@DutchWorks.nl [mailto:hpux-admin-owner@DutchWorks.nl] On Behalf Of BAKHSHESH Kazem
Sent: Monday, June 12, 2006 9:17 AM
To: hpux-admin@dutchworks.nl
Subject: [HPADM] boot over SAN
Hi admins,
We use SAN and even if prefere booting from intrenal disks my bos
realize taht there must be some real advantage to boot over SAN.
I appreciate if you have the expriences about Boot HPUX over SAN.
Our environement is mix of
HPUX : the differentes HP model(E,D,L,N, ....), EMC( Connectrix, Symmetrix ) and MACDATA switch.
Questions:
1. If you're booting from SAN (or did in the past),
what problems/advantages did you encounter?
2. What SAN solution and fiber HBA combination were you using?
3. Does a particular SAN solution (EMC) make it easier/harder to implement SAN
booting?
Cordialement(Best regards)
Kazem Bakhshesh(Administrateur Système : HP-UX)
E-Mail : bakhshek@essilor.fr
Tel : 01.72.94.73.09
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