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Oracle ASM - XP12000 - autopath - how to adress raw devices

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Oliver Eichhorn
Occasional Contributor

Oracle ASM - XP12000 - autopath - how to adress raw devices

Hi,

we have set up 256 LUNs in our XP12000. Those are presented via 4 HBAs to the host, which are seen 1024 times.

Now we configured autopath to Round Robin those LUNs, so only 256 LUNs should be adressed to Oracle ASM. Ist this the correct procedure?

We chmodded all /dev/rdsk/* device files related to those LUNS (chown oracle:dba, chmod 660).

So we get the usal output of "autopath display all"

Details for path : /dev/dsk/c6t2d0

Load Balance Policy : Round Robin

=========================================================
Device Paths Device Status
=========================================================
/dev/dsk/c6t2d0 Active
/dev/dsk/c10t2d0 Active
/dev/dsk/c14t2d0 Active
/dev/dsk/c18t2d0 Active
=========================================================

Oracle ASM is supposed to adress one raw device per LUN. So i suppossed giving /dev/rdsk/c6t2d0 should be a valid device for Oracle ASM.

Now ASM complains about having this device four times and on top of that ist complains about the device beeing already used.
ASM won´t work this way? But why?

Any ideas?
What´s the trick about ASM and autopath?

OS is 11.23v2 Itanium on a rx4640

best regards
tanx for any help ;)
7 REPLIES
Jean-Luc Oudart
Honored Contributor

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

Hi,

as you mention its seems that ASM cannot handle the same disk twice (or more !).

check this link
http://www.oracle.com/technology/tech/linux/asmlib/multipath.html

and also Metalink doc id 309815.1 "Configuring Oracle ASMLib on Multipath Disks"

Regards
Jean-Luc
fiat lux
Unix Team_13
Occasional Visitor

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

obviously ASM can´t handle a device, which is seen twice.

Is there a possibility to configure securepath or autopath to only present 1 device file four 4 LUNS? I wouldn´t know - can someone verify that?

I was wondering about configuring 16 LUNS via LVM to be one rlvol, which can be used by ASM. This solution was denied by the oracle engineer.



Oliver Eichhorn
Occasional Contributor

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

ups, i was logged in to itrc from my companies workstation with the wrong ID ...
The posting above is my response
Yogeeraj_1
Honored Contributor

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

hi,

i don't know if this will help, but still can you check the ASM_DISKSTRING parameter.

regards
yogeeraj
No person was ever honoured for what he received. Honour has been the reward for what he gave (clavin coolidge)
Duncan Edmonstone
Honored Contributor
Solution

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

Yogeeraj is on the money... use the ASM_DISKSTRING to limit what Oracle is allowed to see...

I wouldn't point Oracle at /dev/dsk anyway - beetter to create soft links so you can easily move things around later if you want to...

mkdir /dev/asm
ln -s /dev/dsk/c6t2d0 /dev/asm/disk1
ln -s /dev/dsk/c6t2d1 /dev/asm/disk2

etc...

ASM_DISKSTRING=/dev/asm

or something like that...

HTH

Duncan

HTH

Duncan
Oliver Eichhorn
Occasional Contributor

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

Thank you all!

Now my conjecture, ASM has to handle the multiple LUN management not Seurepath is prooven...
Bryan Rooney
Frequent Advisor

Re: Oracle ASM - XP12000 - autopath - how to adress raw devices

This is an old thread, but not closed, so I thought I'd add a commement. I would not create softlink or mknods of Autopath created and managed device paths. We did that and found out the hard way that Autopath does not failover to a path it did not create or does not manage. So ASM must see either the hpap virtual devices or the lead devices it creates for each LUN. I think the hpap devices might be better since HP-UX has a nasty habit of changing the device paths for SAN hardware failures and the like. The Oracle ASM asmdiskstring INIT parameter is the way to make single ASM LUNs visible to Oracle. Oracle ASM does not want to see the multiple paths that Autopath provides, so asmdiskstring can be created such that only the lead device or hpap virtual device of each LUN is visible. Please see attached PDF for clarification.