Moving SSA RAID array to different server

[mkharris]

I am trying to move an SSA RAID-5 array from one machine to another. Unfortunately, now that the discs are connected to the new server, I am unable to access the RAID-5 array.

After running cfgmgr, the system found the SSA pdisk devices, but did not add an 'hdisk' for the RAID-5 array, although clearly it knows that the RAID-5 array exists:

% ssaraid -I -z -l ssa0

pdisk0 0060947EBFC200D member n/a 18.2GB Physical disk
pdisk1 0060947EEA5400D member n/a 18.2GB Physical disk
pdisk2 0060947EEA6400D member n/a 18.2GB Physical disk
pdisk3 0060947EEB5400D member n/a 18.2GB Physical disk
pdisk4 0060947EEBDB00D member n/a 18.2GB Physical disk
pdisk5 0060947EEE8C00D member n/a 18.2GB Physical disk
pdisk6 0060947EF22200D spare n/a 18.2GB Physical disk
99BA3C5EBFD24CK 99BA3C5EBFD24CK unknown 0 RAID-5 array

When you try and change the use of the RAID-5 array to 'system disk' (which I want to do in order to get an hdisk device created), I get the following error:

% ssaraid -H -l ssa0 -n '99BA3C5EBFD24CK' -a use=system -d
ssachg: Object 99BA3C5EBFD24CK is not known
ssaraid: Change method failed for 99BA3C5EBFD24CK

Does anybody have any suggestions for how I can 'import' this RAID-5 array, and keep the data it contains, into the new system? Is there something I could create in the ODM? It almost seems like a vicious circle - the status of the RAID-5 array is unknown because there isn't an hdisk, but I can't create an hdisk because the array is unknown...

Thanks
Mark

 

[aixqueen]

I may be wrong...so take what I say with a grain of salt. But I thought it was near impossible to move raid 5 disks to a new machine. I thought when you were doing hardware raid, you had to back up the entire raid.....move the adapter to the new machine, attach the disks, recreate the disks as candidates in an array, then restore the data.

When a card goes bad...the info is in the odm....There are no special procedures to follow or preparation work required when replacing a faulty adapter card. A straight swap is required and the new adapter will pickup all the details from the disks during
reboot...of course you have to make sure that it is in the same "slot" as the old adapter. Since that data was never there.......not sure you can...........

As I say I may be wrong, but I really thought it had to be done all over again if you moved it.

 

[aixqueen]

I did a search on Google....or comp.unix.aix...and they talk about being able to do it with a simple importvg.....(I am doubtful) but maybe one of them can give you step by step?

Good Luck

 

[mkharris]

Thanks very much for taking the time to look into this. If you searched comp.unix.aix, you probably found a posting with almost identical text, from another person. That's because there's 2 of us out here trying to sort this out .

Our next course of action is to make up a loop that includes both adapters from both the source and target server. ( Previously we had a simple loop that we cabled across from one adapter to another ).

I'll post the results of this later.

Mark

 

[aixqueen]

I would be interested to know if you figure it out...
I imagine if you had both machines claim the disks similar to a fail over situation...varyied on for one machine and concurrent for the other, then claim it on the new machine....maybe..........

the loop with both adapters seems to be the best way to go........

Good luck

 

[bi]

I have used exportvg and importvg to move several SSA RAID5 arrays from one system to another. Both systems had ssa cards and both saw the disks. It took planning ahead to be able to do this, however. I had to make sure there were no other filesystems that needed to stay on the first box in the volume group that I was going to import into the second box.

As to the hdisk device problem: I have had this problem before where the disk shows up as its physical number number rather than an hdisk number. I think you have to do a rmdev command. (I'm out of town and not near an AIX system, so I can't be more specific.) Then try cfgmgr again. You might be able to import the vg using that physical device number, but I'm not sure about that. I would strongly recommend having the disks backed up before you start doing a lot of messing around.

Check out what smit has to say about physical to logical disk relationships and logical to physical. (The smit path is something like Devices/SSA disks/Physical Disks (and Logical Disks). You should explore what smit has to say about the SSA disks it is seeing.

 

[mkharris]

We did previously try both things you suggested - using rmdev / cfgmgr again, and using importvg with the physical device number. I didn't keep the details of how these failed, but they did.

However, I'm pleased to say that recabling both adapters into the loop seemed to do the trick - we were able to split the mirrored RAID5 config and import the 2nd copy to the other system.

All we need to do now, is make sure both arrays are still accessible if we cable back to separate loops again ( We have to do this because it's all part of how we are cloning a system just before transporting it elsewhere.)

Thanks to both of you for the advice.
Mark

 

[AIX5L]

Hi All

I have the solution of your Problem.

I your other System you can see the RAID array in smitty ssa_array "list all defined Raid-arrays" there you can see the RAIDs whith the hdisks and the new added with an ID-Number FC.............

After the cfgmgr you can see only the pdisks in your System ( lsdev -C ¦ grep disk )

In smitty ssa logical disk -- add an logical ssa disk: Connection Adress is this ID-NR.
then you have the hdisk available and the RAID is online.

In diag - Task Selections - SSA: you can see the Link Verification and so on......;->

Good Luck.