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1 tech100 commented Permalink

btw. in my case, ds4800 disks vscsi mapped have even one more "column" on output:

# lspv -u
hdisk0 00f6fc69c4da9df7 rootvg active 544E4E474600A0B40004657E40000BFE44F4C7C7E0F7475 FAStT04IBMfcp05VDASD04AIXvscsi740754d7-fd44-64e7-4b95-c744bb4f4675
hdisk7 00cfb47ab74d4977 nimvg active 544E4E474600A0B40007746C40000A7A944BBB4900F7475 FAStT04IBMfcp05VDASD04AIXvscsi74b9795e-eb4a-6c4d-44a4-cba7a4b0e4df

2 UrbanBiel commented Permalink

Hi Mark
thanks for feedback

I believe it is not extra column, but there is a space in the UDID.
Could you please send lsattr -El hdiskX and lscfg -vpl hdiskX, where hdiskX is the hdisk on VIOS (under oem_setup_env)

3 JLGuyot commented Permalink

I tried to figure out where the UUID was coming from (I digged a bit the ODM but didn't find anything there).
It seems it identifies a disk uniquely but i'm not sure if that's an ID that is passed to other machines as well and if it can be used to list all disk from a SAN.
I guess i'll stick to the PVID.

4 UrbanBiel commented Permalink

I'm not sure, whether UDID will keep the same when you move a disk between systems. PVID is definitely the best way to do it. I'm using UDID to quickly see "where this disk comes from" or "where is this disk in missing state gone"?

5 JLGuyot commented Permalink

Actually i was refering to the UUID and not the UDID.
UUID is a new information given with lspv -u.
And i was wondering if UUID could be used instead of PVID because sometimes disks don't have a PVID but have an UUID and maybe this information could be used to locate LUN accross our servers (we have a huge load of servers, SANs and LUNs).

6 UrbanBiel commented Permalink

Indeed I overlooked UUID and UDID. It is a very good question about UUID, I have no clue where it comes from and I wasn't able do decipher any logic behind it too. Would be nice to use it for ASM, GPFS etc disks if it's unique.

7 armink commented Permalink

I have both UDID and UUID inside a SVC environment. But there seems to be a bug in the output when the UDID gets quite large (like in my enviroment). There is a missing space (or tab) between UDID and UUID:
lspv -u|grep hdisk0
hdisk0 00c7918cc44d1fb3 rootvg active 48333321360050768019081BBD8000000000009D804214503IBMfcp05VDASD03AIXvscsifb5e55f4-06fb-b590-d461-9ac0f7b54154
But the UDID really is this:
/usr/bin/odmget -q 'name like hdisk0 and attribute="unique_id"' CuAt
value = "48333321360050768019081BBD8000000000009D804214503IBMfcp05VDASD03AIXvscsi"
So the UUID must be "fb5e55f4-06fb-b590-d461-9ac0f7b54154".
I could not find the UUID in any ODM.
The output problem appears in AIX 6.1 TL7, TL8 and AIX 7.1 TL1, TL2

We are using UDIDs for quite some time to find out which disk is on which box in which location. In this case it's a SVC (2145), box identifier is 1BBD0, it's vSCSI, SVC-UUID is "60050768019081BBD8000000000009D8". All you need to know is which part indicates the box and therefore the location to e.g. create mirror pools automatically.