strange problem of FAST with AIX

[polani]

Dears ,
We have fastT700 storage subsystem which is working in direct managed subsystem.
The storage manager software is installed on an AIX box.We define three raid arrays and assigned to three AIX boxes.
Every AIX box has two FC adapters.
Now the problem is that at certain instances , vg commands like varyoffvg , varyonvg hangs on FAST raids and on FAST manager software error appears saying that logical disk is not on its preferred path.
when we redistribute the logical disks , every thing becomes ok but then once again after some time abnormality reappears.
Now my question is that why this is happening as there is no hardware errors on FASTt700 controllers.
please advice!
Polani

Here comes polani Once again!!!

P690 Certified Specailist
HACMP & AIX Certified Specailist
AIX & HACCMP Instructor

 

[theycallmetim]

AIX has a few limitations.

The main one is:

a LUN can only be presented across 1 controller to 1 fiber card per host.

That being said we had this problem as well. You need to get up to bos.rte.lvm 5.2.0.18 It fixes the varyonvg hang under an HA environment. (Ps if you vary it on by hand while it is hung it will work and continue)

*Note - this fix seems to also create a problem. Under HA during a failover if more than 1 NFS cross-mount is used, the mount command will hang now too.

1 last thing. AIX does not support LUN 31 (or the Access LUN) on fastT for direct management from the AIX host. You will need to remove it if you have not done so already.

 

[polani]

Dear,
Thanks for your response!
I am getting the view from ur response and my problem also that FAST storage has number of limitations on AIX.
Your statement mean :
I can not use two FC cards on AIX hosts to access to one LUN on FAST Storage.... That is very strange because it mean there is no role of RDAC driver on AIX and there is no FC failover supported on AIX.
If this is correct, i have to define one sigle port on FAST storage software for each LUN while at present i have used two ports per storage partition accessing a single LUN.
I am also upgrading the ML of AIX 5.2 to ML02 so that latest fix for bos.rte.lvm can be included on OS.
TWo more questions:
1.Access Lun should be removed from default group or on individual storage partition groups using AIX hosts.
2.Is this possible to use shared LUN between two AIX hosts without using HACMP.....i have used this for SSA for number of years by using manual varyonvg and varyoffvg commands.

I will really appreciate if you and other guys come with some good guidelines and suggestions for me.

Polani

Here comes polani Once again!!!

P690 Certified Specailist
HACMP & AIX Certified Specailist
AIX & HACCMP Instructor

 

[theycallmetim]

To answer your single point of failure question.

Yes, you can have 2 FC cards shown to the same LUN, but only 1 can be active. 1 for fail-over. No more than 2.

The latest lvm fileset is not included in ML2

Yes, you can used a "shared" lun, what I'm saying is the default LUN 31 that shows up on FastT needs to be removed from the AIX hosts.

You should create a host group in Storage Manager and show the disks to the group, that way you don't need to configure each individual host.