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Re: HBMM Experience

 
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Jack Trachtman
Super Advisor

HBMM Experience

I'm excited to see that HP finally released the
HBMM (Host-Based Mini-Merge) functionality (as a Patch), but I'm leery of installing the first release of something of such an obviously complex nature (I've got only 1 cluster which is for production so no place to test this feature). I've extraced the doc from the patch and see that there are some implementation decisions to be made.

Does anyone have any experience yet with HBMM?
20 REPLIES 20
John Gillings
Honored Contributor

Re: HBMM Experience

Jack,

Sure! We in HP have got LOTS of experience with it :-) It's been heavily tested for a very long time, including an external field test over the past 6 months or so.

We're also very excited to see it finally released, as this is a solution to one of the biggest headaches for customers.

I can understand OpenVMS customers being reluctant to install something this new on their production systems, but those of you with test systems, please give it a good thrashing to make certain that we haven't missed anything. The sooner we can get this rolled out to everyone, the better.

Jack, one possibility is to install the kit on production, but not enable mini merge on all your disks. You should still be able to use merge prioritisation and other new features.
A crucible of informative mistakes
Wim Van den Wyngaert
Honored Contributor

Re: HBMM Experience

No mini-merge chez nous.

But we are on 7.3 and are using the mini-copy on every reboot. Without any problem except that 1 time the boot was interrupted when the shadow mini-copy was active. Then we had 2 members of a shadow set that were not the same. There is a patch for that.

So, if you test it, focus on interrupting it while it is doing the mini-merge.

Wim
Wim
Kris Clippeleyr
Honored Contributor

Re: HBMM Experience

Jack, and others,

Be aware that the HBMM V0100 kit has been put on hold by engineering due to a slight problem that will be fixed within a few weeks with the V0200 version of this patch.

Greetz,

Kris
I'm gonna hit the highway like a battering ram on a silver-black phantom bike...
Ian Miller.
Honored Contributor

Re: HBMM Experience

I've just read the hold notification sent via openvms.org - sounds a like a significant problem and makes me wonder about all that testing that has been going on.
____________________
Purely Personal Opinion
Jan van den Ende
Honored Contributor

Re: HBMM Experience

Jack,


I just received this:



Engineering Hold Notice for VMS732_HBMM-V0100

PROBLEM DESCRIPTION:

If a shadow set member device name is specified with the SET SHADOW command,
the command will fail with the following error:

%SYSTEM-F-IVDEVNAM, invalid device name

This failure occurs even though it may be valid or necessary to specify a
shadow set member device name with the SET SHADOW command qualifier that was
used.

For example:

$ SET SHADOW $1$DGA107:/COPY_SOURCE
%SYSTEM-F-IVDEVNAM, invalid device name

The qualifiers that should allow a shadow set member device name are:
/COPY_SOURCE, /FORCE_REMOVAL, /MEMBER_TIMEOUT, /READ_COST, and /SITE.

Commands that take a shadow set name work correctly.

PROBLEM RESOLUTION:

This issue will be corrected by the future VMS732_HBMM-V0200 ECO kit. Expected
release timeframe for this kit is one to two weeks.

WORKAROUND:

There is no workaround for this problem. If customers experience this problem
the VMS732_HBMM-V0100 kit can be removed from the system with a PRODUCT UNDO
PATCH command. The PRODUCT UNOD PATCH comand will remove the last patch
installed. If patch kits were installed after the VMS732_HBMM-V0100 kit,
those kits will have to be removed before the HBMM kit can be removed. Note
that this will only work if the kit was installed with the SAVE_RECOVERY_DATA
option.

If the HBMM kit was not installed withe the SAVE_RECOVERY_DATA option but
replaced files were renamed archived as image_name_OLD, the kit can be removed
by renaming these archived images to the normal image name (removing the
_OLD) and making them the latest images on the system.

If neither of the above options can be used, the kit can be removed by
restoring a pre-kit installation backup.

After removing the VMS732_HBMM-V0100 kit the system must be rebooted.




guess WE will be waiting some more.
I am the one that was known in all european DECUSses to ask about this issue every time again in every Engeneering Panel, so it might be assumed that I am eagerly waiting,
but a few weeks more waiting is all there is to it, I guess....


Sorry to bring such bad news.


Jan


Don't rust yours pelled jacker to fine doll missed aches.
Jan van den Ende
Honored Contributor

Re: HBMM Experience

Sorry,
I only now noticed Kris' entry. Don't know how I missed it.

Jan
Don't rust yours pelled jacker to fine doll missed aches.
Zahid Ghani
Frequent Advisor

Re: HBMM Experience

Jack, We have asplit site cluster and have been eagerly waiting for HBMM. I did get involved in the testing of 7.3-1 version using the test facilities provided by HP. I spent a day testing and trynig to break it. The time it took to complete a mini merge was in the rang of 2-4 minutes.
I am planning to to introduce HBMM around November time and just like you am a bit nervous and would prefer the reassurance of some body else having tried on their production system.
As a suggestion may be you could your HP contact to see if they can provide some test facilities. Also I would be interested on what other peoples plans and their exepeince of HBMM.
Robert Brooks_1
Honored Contributor

Re: HBMM Experience

As one of the members of the team that created HBMM, I'm certainly interested in this thread!

While the minimerge functionality is clearly
the focus of our work, we also spent a fair
amount of time on the copy/merge priortization scheme.

Through judicious use of
$ SET SHADOW DSAn/PRIORITY = n and the
SHADOW_REC_DLY system parameter, it is now
possible to predict with 100% certainty the
order in which recovery operations (that is,
a merge or a copy) take place on a system
and cluster.

Has anyone tried this feature yet?

(note: we apologize for the hold placed on the V7.3-2 kit; we've solved the problems
that caused the initial hold, and just found
another problem that happened due to oddly-failing hardware. Without the failing
hardware, it's unlikely that we'd have found this issue. Unfortunately, the hardware
died, and reproducing the mode of failure
has not been easy).
Jack Trachtman
Super Advisor

Re: HBMM Experience

Robert,

Aren't the SET SHADOW DSAn/PRIORITY = n and the SHADOW_REC_DLY features only available after the HBMM patch is installed? I just checked the SET SHADOW Help on a V7.3-2 system and don't see a reference to /PRIORITY.