topic Re: cXtXdX ????????????? in Operating System - HP-UX

cXtXdX ?????????????

Adeel Zia — Thu, 17 Jun 2010 08:28:01 GMT

while creating a physical volume we use this pv-path something like /dev/dsk/cXtXdX how do I come to know that what is my cXtXdX because there are a lot of disk attached when I do a "ioscan -funC disk"

Re: cXtXdX ?????????????

rariasn — Thu, 17 Jun 2010 08:37:34 GMT

Hi,

# lssf /dev/dsk/cXtXdX

rgs,

Re: cXtXdX ?????????????

sudheerch — Thu, 17 Jun 2010 09:17:56 GMT

if it is a scsi disk u have to check the disk physically to which controller, target and disk

if it is from storage u will find the lun number from #ioscan -m lun command
storage admin will give u new lun number

Re: cXtXdX ?????????????

Adeel Zia — Thu, 17 Jun 2010 09:37:58 GMT

Thanks for the early reply

I did this lssf on one of my SAN disks,
I did "lssf /dev/dsk/c6t15d0"

The output was something like:

sdisk card instance 6 SCSI target 15 LUN 0 section 0 at address 1/0/2/0.1.0.0.0.15.0 /dev/dsk/c6t15d0

What do I assume of this???

Re: cXtXdX ?????????????

Adeel Zia — Thu, 17 Jun 2010 10:12:40 GMT

I hv found that in a storage environment the LUN is our dX of cXtXdX,am i correct?
if yes how can we trace our cX and tX

and that ioscan -m lun command is not working illegal operation is the out put which says cant use the -m bcoz its not listed in the manual,i am using an HP-UX B.11.11

Re: cXtXdX ?????????????

Torsten. — Thu, 17 Jun 2010 10:12:54 GMT

You usually know this from hardware path or optional tools like xpinfo/evainfo.

Re: cXtXdX ?????????????

rariasn — Thu, 17 Jun 2010 10:19:27 GMT

Hi,

0/20/0/0.1.1.0.2.4 is:

0/2/0/0 = HBA/Interface Card
1 = Domain (=switch no)
1= Area (=physical port no)
0= Port (always 0 in a switched fabric)
0 = Virtual SCSI Bus
2 = SCSI target
4 = SCSI LUN

http://forums11.itrc.hp.com/service/forums/questionanswer.do?admit=109447626+1273675694670+28353475&threadId=1067960

rgs,

Re: cXtXdX ?????????????

Torsten. — Thu, 17 Jun 2010 10:26:17 GMT

>> I hv found that in a storage environment the LUN is our dX of cXtXdX,am i correct?

A little bit correct, for LUN 0 to LUN 7. ...

Re: cXtXdX ?????????????

Elmar P. Kolkman — Fri, 18 Jun 2010 10:36:40 GMT

in most cases, the lun number is the same as the target number multiplied by 8 + lun number.
So if we have cXtYdZ, your lun number = (Y*8)+Z.

To make sure you're not overwriting a disk you already had in use, you can run a pvdisplay on the device. Or do a strings on /etc/lvmtab.
But that only works if your system is the only one seeing/using the disks. Even in a cluster you might run into problems with lvmtab and pvdisplay when a volumegroup has not been made known on all nodes.

To make sure which lun you are using, there are tools which might help you. For instance, when the LUN is created on a XP you can use the xpinfo command to see the LDEV information. And when using NetApp filers, sanlun is a good command to make sure the device is for the LUN you wanted.

Re: cXtXdX ?????????????

Rita C Workman — Fri, 18 Jun 2010 11:26:23 GMT

On your other thread you mention you have SAN attached disk array, not scsi connected.

You need to look at the storage vendor for what utilities they have so you can determine which SAN disk goes to which c-t-d-.
For example I run EMC storage. So I can list out all the EMC disk # with a simple command. The EMC disk # is going to be different than the servers disk number. But, once this disk is presented (mapped & masked to server) and the special device files (/dev/dsk/c-t-d-) are created, I have another command that I can run that will show be the EMC number & the associated c-t-d for it.
Since your example just shows..."OpenStorage", I'm not sure what that might be.

Check what manuals came with your new array; call the vendor...and start reading.

Regards,
Rita

Re: cXtXdX ?????????????

Rita C Workman — Fri, 18 Jun 2010 11:31:22 GMT

...more importantly...

Identifying one disk on a new array is one thing. But keeping track of all the disk properly is a whole issue.

You need to have a plan of keeping track as to what disk is used/what disk is free. And generally what system has the disk. Again, the vendor may have utilities to help you with this.

You need some method of organization to ensure you do not find yourself grabbing the same disk twice! Because whatever application had it first, will lose.

Rgrds,
Rita