Showing results for 
Search instead for 
Did you mean: 

can dd rdsk but not dsk

Go to solution
Wes Kaufmann
Super Advisor

can dd rdsk but not dsk

I have a 11.31 IA 64 system. The system had a problem and I have recoved everything but access to vg01.

dd to raw device file works but not to a block file.

dd if=/dev/rdsk/c11t0d1 of=/dev/null bs=1024k count=200
200+0 records in
200+0 records out
ac2opv:/stand#: dd if=/dev/dsk/c11t0d1 of=/dev/null bs=1024k count=200
dd read error: I/O error
0+1 records in
0+1 records out
Acclaimed Contributor

Re: can dd rdsk but not dsk

Whatever you do with 11.31 regarding disks, you should use the new device files, e.g.



# ioscan -m dsf

to find out.

Hope this helps!

There are only 10 types of people in the world -
those who understand binary, and those who don't.

No support by private messages. Please ask the forum!

If you feel this was helpful please click the KUDOS! thumb below!   
Wes Kaufmann
Super Advisor

Re: can dd rdsk but not dsk

Doesn't matter if I use legacy or the new persistant device file. Using dd on the block file fails.
Honored Contributor

Re: can dd rdsk but not dsk

Very interesting issue.
Have you look this thread
In fact, with my experience, Hpux 11.31 does not like powerpath at all, but if you have an EMC array with actif/passif controler [it could happen with old firmware], it should be clearly more interesting to install powerpath. So normally dd can read raw or block file, i think but not sure, this issue is probably about multipathing.
Hope it helps
Wes Kaufmann
Super Advisor

Re: can dd rdsk but not dsk

Actually, same exact issue in the link you provide.

I was using PowerPath and suddenly I was having problems with A SG lock disk. I was going to try removing powerpath and just use the legacy device files. But, on the good system I can do a dd on the block files, same array on the bad system doesn't do a dd on block files.

So based on the last thread perhaps powerpath has left some goodies?

FYI, I was going to use the new persistent device file but was having timeout issues with a EMC CX500 array so I than tried powerpath and it mostly worked for a month. Than suddenly an issue appeared. When one node in a SG cluster rebooted the lock disk on live node would go down. I found that I could get the lock disk on the live node back up by simply running a ioscan -f.....

So trying to go without powerpath and just do legacy device files with alternate links. Not a lot of IO so wasn't worried about loadbalancing.
Wes Kaufmann
Super Advisor

Re: can dd rdsk but not dsk

I don't believe I will have time to resolve the issue but I agree that PowerPath probably makes a setting to the system that then makes the system incompatible with direct native connectivity to the array.

I was going to set some attributes with the scsimgr command but I found a patch for powerpath and I'm back in business.

HP support says a EMC array is supported if ALU is enabled so it seems that you would need to turn on ALU.

scsimgr -v get_info -D /dev/rdisk/disk12' we have
Asymmetric logical unit access supported = No

Note, I did run the native Persistent device file for about a week against the EMC array but I would get timeout issues and the volume group would fail for a few hours and than magically turn back on. I had a call open with HP and it was escalated to the lab but I ran out of time and was forced to use PowerPath and put the system in Production.

Installing PowerPath IA64 patch 5.1.1 resolved my issues with a lock disk failing on a SG node.

For now I am stuck with PowerPath since I don't know what settings to change to the system if I remove PowerPath and I will probably still have timeout issues.