topic Re: Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)? in Operating System - OpenVMS

Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)?

JF Muench — Mon, 15 May 2006 16:21:21 GMT

HP OpenVMS Alpha Version 7.3-2 Cover Letter includes the following item:
Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load.

Questions:
1. I'd like to know whether and what VMS Patch kit(s) may have addressed this (I downloaded 15 kits in prep for OpenVMS v7.2-1 to V7.3-2 upgrade but don't see this item in kit docs).
2. What does “many LUNs” (more than ~24 LUNs configured) mean (have 24+ Units in HSG80's)?
3. Can someone quantify “Heavy I/O Load” in this context?
4. Do I possibly need HSG ACS firmware update to prevent this (need/use ACS v8.6F-13 to allow SWCC to work in our SAN config, so am hesitant to change ACS; v8.7 would not work).

If VMS patch kit(s) address this then I'm not as concerned with questions 2 and 3.

Any help/suggestions will be appreciated. Thx!

Re: Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)?

Jefferson Humber — Mon, 15 May 2006 17:37:38 GMT

I seem to remember that an ACS upgrade was released to fix this problem.

I believe that the newer versions of OpenVMS were so optimised that they could flood the HSG and make it fall over.

There was a long thread on this on the ITRC a while ago, but for the life of me I can't find it now.

Reducing DIOLM may of been one of the workarounds, but don't quote me on that.

If I find the thread I'll post it here.

Jeff

Re: Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)?

Jefferson Humber — Mon, 15 May 2006 18:08:40 GMT

http://h71000.www7.hp.com/openvms/fibre/OpenVMS_SAN_Update_files/OPENVMS_SAN_UPDATE.PPT

Re: Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)?

JF Muench — Tue, 16 May 2006 13:55:12 GMT

Jeff,
Thanks so much for your prompt repsonse!

I read HP OpenVMS SAN/Storage Technical Directions white paper and it appears that work done to back port qfull fix from VMS V8.2 to V7.3-2 (via FIBRE_SCSI-V0400) is likely in DEC-AXPVMS-VMS732_FIBRE_SCSI-V0900 kit (which I downloaded already).

I'm not sure if I'll be able to upgrade to HSG ACS 8.8 (may cause other issues for us) but plan to experiment, after VMS 7.2-1 to V7.3-2 upgrade, and probably won't adjust DIOLM (currently 150 with PQL_MBIOLM at 100) as I've been told that DIOLM must be >= PQL_MBIOLM and that related BACKUP issues is addresed via VMS732_BACKUP-V0500 kit (I also plan to install).

I've been told that this article is dated, so whatever updated information anyone can provide on this will be appreciated.

Thanks - John

Re: Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)?

comarow — Tue, 16 May 2006 14:03:26 GMT

One issue, please be sure to
install Backup-0500 which will
reduce /IO_LOAD by default to 8.

That would be the same as reducing DIOLM to
8.

Have fun.

Re: Dual-Controller HSGnnn with Many LUNs Can Crash Under Heavy I/O Load (VMS v7.3-2)?

JF Muench — Tue, 16 May 2006 14:40:51 GMT

Thanks Bob!
I'm speaking with HP Storage team (Dean M) now. Please call Thurs PM or Friday (as discussed).
Best - John