Making High Availability Work on 3000s
January 31, 2011
"We just launched a new A-Class 2-way running 7.5 PowerPatch5," reported Mark Landin not long ago. "This is our first 7.5 system; our two other machines are still on 6.5. The primary use for this system is MANMAN [ERP] with around 170 users."
Landin added that his storage resource for the A-Class is a VA7410 array running off of two PCI FiberChannel Host Bus Adapters, one DTC 16, and two SureStore DDS-2 tape drives running off the LVD SCSI interface. "So, for this kind of system," he asked, "what are the 'must have' patches that we should install on top of PP5?"
Advice from the 3000 community brought the High Availability Failover (HAFO) techniques into the discussion. An HP engineer who helped keep the 3000 up to date with storage added his take on HAFO abilities for MPE/iX systems like the A-Class.
It works on the VAs because all the LUNs are seen down both paths. Don't forget to put the correct firmware on the VA7410 controllers and disk. To update the firmware CommandView is required.
The latest firmware bundle (that I know of) can be found on HP's website.
Jack Connor of Abtech added details and a vote of confidence for HAFO on the 3000.
Under SYSGEN>IO>HA you define your LDEVs and primary path and then the alternate card path. No need for multiple config groups.
I suggest you alternate LDEVs between cards so half are on one attached to Controller 1 on the VA, and the other half on card 2 going to VA Controller 2.
Works like a champ... you can lose a fiber card, cable, or VA controller and you'll get a series of tellop/replies on the console, but it keeps right on running using the single path.
When you've fixed the problem (say a failed controller), you can go into the HA utility under SYSGEN and move them back to the normal path.
Jim Hawkins, who supported the 3000 and engineered from inside HP's labs until HP shut the doors on both, explained the history of how HAFO solutions like the 7410 can work with the 3000.
HAFO could work on any SCSI Disk device where you can see LUNs on more than one port (really all the smarts are in the scsi_disk_and_array_dm code, which was used for all SCSI disks except the oldest SE devices). Original HAFO was with XP256 F/W SCSI, but that was a pretty clunky device even when it was state of the art.
HAFO really didn't become useable until FiberChannel. I led the FC-based effort and we did all of our work on XP and then VA devices because they were what worked at the time; those are the configurations that were officially supported, blessed, and used successfully by many customers. We did evaluate EVA products and they did "work" as disks but they didn't have this "LUNs visible on more than one path" feature until way too late for lab development and certification.
HAFO probably would work on EMC, though our co-development/marketing agreement with them had terminated by the time HAFO was developed -- they did continue to advertise support for MPE/iX systems long after we stopped working with them.
Signing off with the customary "Your Mileage May Vary" disclaimer, Hawkins added that he's noticed that "more stuff seems to be "findable" in the HP Business Support Center. A search for "MPE HAFO" gives many hits of PDF files including:
and an old Jazz article, worth reading if you're new to FC.