Date: 10-08-20  Time: 11:37 AM

Author Topic: Active Mem Sharing on P6 DUAL VIOS Config  (Read 14186 times)

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martinwhitear

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Active Mem Sharing on P6 DUAL VIOS Config
« on: March 23, 2011, 11:59:22 AM »
I need to upgrade sddpcm and host attachment on both VIOS LPARS but need to know if it's possible to direct all paging to one VIOS whilst the other is being upgraded. (Is there a chdev command or similar)? I've been scanning through the Red Book and internet but can't find anything.
IBM support have advised that all client LPARS will need to be halted in order to perform maintenance on AMS LPAR!!!!

Surely this is not correct (I hope not anyway)?

Here's the attributes for one of the paging devices:

LogicalUnitAddr 0x8200000000000000      Logical Unit Address         False
aix_tdev        hdisk101                Target Device Name           False
client_reserve  no                      Client Reserve               True
partition_id    26                      Client Partition ID          False
redundant_usage yes                     Redundant Usage              True
vasi_drc_name   U9117.MMA.066A712-V2-C5 VASI DRC Name                True
vrm_state       active                  Virtual Real Memory State    True
vtd_handle      0x20000125fa32c749      Virtual Target Device Handle False

So I'm thinking that chdev -dev vrmpage1 -attr redundant_usage=no might false the paging to the other VIOS??

Any ideas?

Thanks

Martin
« Last Edit: March 23, 2011, 03:23:52 PM by martinwhitear »

Michael

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Re: Active Mem Sharing on P6 DUAL VIOS Config
« Reply #1 on: March 28, 2011, 06:35:47 AM »
I had not thought about it before actually, and not had the hardware to play with it properly.

From my understanding it was possible, or I should say - is possible, to configure AMS such that the configuration is not dependent on a single VIOS. At a minimum this would need to imply that the device being used as AMS paging is the same LUN being seen by both VIOS.

I would test this as follows: -- it will require the support of your SAN/storage team (maybe you are both!) create a new LUN and a test partition. Configure both into AMS the same as the partition you are focusing on. Install and verify AMS is functioning. Rather than shutdown the partition - and rmdev wont work either I expect (once the client is active) remove the LUN (temporarily) from one of the HBA (say vios 1) and verify that the client partition can continue to live using AMS; restore path; verify. If all is still working then try the chdev command (btw - was that on the client, or on the VIOS - as I said I have not used AMS since learning the basics).

Not had the (personal) hardware to try it on. And, the lack of google hits makes me think that not many sites use AMS in production. AME is more popular (as is WPAR).

Note: If possible test on a different system. If IBM support is saying you need a reboot I would be cautious about removing a path - if the chdev command is being run on the AMS client - that is probably the safest start (my LUN removal is intended to mimic a VIOS failure/reboot).

I'll ask around and see if I can get any better advice.

martinwhitear

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Re: Active Mem Sharing on P6 DUAL VIOS Config
« Reply #2 on: March 28, 2011, 08:31:35 AM »
Thanks for your reply Michael - I have confirmed with my colleagues here that the dual VIOS AMS configuration is functioning correctly and they have rebooted primary and secondary VIOS LPARS in the past with no impact to their clients.

I just need to ensure that the backing devices on the VIOS receiving the SDDCPM update, are not in an active state when I attempt to install the drivers. We don't currenty have any test AMS environment to play with so I will have to ask if we have any spare capacity anywhere to create one.

PS you may remember sitting next to me when you were providing services to SSE (NPIV configuration) a few weeks back.

I'm working for another client now.

Speak soon

Martin

Michael

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Re: Active Mem Sharing on P6 DUAL VIOS Config
« Reply #3 on: March 28, 2011, 12:21:18 PM »
Yes, I remember SSE. But I was thinking it was a bit longer back than a few weeks :)

Quote
I just need to ensure that the backing devices on the VIOS receiving the SDDCPM update, are not in an active state

Sounds to me like they are saying the LUNs need to be "disconnected" at the SAN level - which may imply that you must get the SAN connection removed from the VIOS HBA - maybe the chdev approach would be enough to be able to do a rmdev (device to defined, i.e. inactive state).

However, I wonder what the effect is if VIO1 and VIO2 have different levels of SDD installed - for a short while. Probably not a great effect.

In thinking a bit further - my plan B. If rebooting VIOS does not present an issue I would shutdown the VIOS partition and reactivate with a new profile - with no HBA and/or at least no AMS support in the profile (let's name the profile "upgrading"). This implies that VIOS rootvg support is currently coming from internal disks rather than from SAN. What sounds appealing to me is that - from the client partition perspective - it is business as usual. And restoring service is just doing a shutdown, and reactivating with the "production" profile.

martinwhitear

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Re: Active Mem Sharing on P6 DUAL VIOS Config
« Reply #4 on: March 28, 2011, 02:01:30 PM »
Hahaha - the weeks fly by and it was probably before Xmas when you were on-site. I've managed to get my hands on a new P7 frame that is currently being set-up for test / DR.
Then I'll be able to test the 'upgrading' profile theory.

Many thanks for your advise. I will post the results on the forum for future reference.

Martin

Michael

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Re: Active Mem Sharing on P6 DUAL VIOS Config
« Reply #5 on: March 28, 2011, 04:22:42 PM »
Quote
I will post the results on the forum for future reference.

Yes, it was last year, before Xmas.

Many thanks for the future hits  8)

martinwhitear

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Re: Active Mem Sharing on P6 DUAL VIOS Config
« Reply #6 on: July 05, 2011, 09:19:16 AM »
Hi Michael - I eventually reached a solution to the AMS paging issue and upgrading SDDPCM. So as promised here's how I managed to force AMS to primary or secondary VIOS:

## To show which AMS paging the LPARS that are using shared memory are using:

ssh -n -2 hscroot@$HMC lshwres -r mem -m $FRAMENAME --level lpar --filter "lpar_names=$LPAR $DESC" -F lpar_name,curr_paging_vios_name |egrep -v "null" (where $HMC is the hmc name, $FRAMENAME is the managed server name, $LPAR is the LPAR name, $DESC is the profile's description e.g:testlpar Test AIX61 Server)

output will look something like this:

testlpar Test AIX61 ,testvioa Virtual I/O Server 1

## To toggle from primary to secondary:

ssh -n -2 hscroot@$HMC chhwres -r mem -m $FRAMENAME -p "$LPAR $DESC" -o so (where $HMC is the hmc name, $FRAMENAME is the managed server name, $LPAR is the LPAR name, $DESC is the profile's description e.g:testlpar Test AIX61 Server)

Then check that AMS has been switched to the 2nd of the 2 VIOS LPARS by running the first bit of syntax again.

testlpar Test AIX61 ,testvioa Virtual I/O Server 2

Hope this is helpful

Regards

Martin