pvcreate on an iSCSI connected disk

[Scott Frye_1]

I see my disk when I do an ioscan -fnC disk but when I do a pvcreate on it, it returns nothing (/dev/dsk/c8t0d0 is my iSCSI connected disk). Any thoughts?

# ioscan -fnC disk
Class I H/W Path Driver S/W State H/W Type Description
==========================================================================
disk 0 0/0/1/1.2.0 sdisk CLAIMED DEVICE HP 36.4GST336753LC
/dev/dsk/c1t2d0 /dev/rdsk/c1t2d0
disk 1 0/0/2/0.2.0 sdisk CLAIMED DEVICE HP 36.4GST336753LC
/dev/dsk/c2t2d0 /dev/rdsk/c2t2d0
disk 2 0/0/2/1.2.0 sdisk CLAIMED DEVICE HP DVD-ROM 305
/dev/dsk/c3t2d0 /dev/rdsk/c3t2d0
disk 4 0/10/0/0.24.0.239.0.0.0 sdisk CLAIMED DEVICE DGC CX600WDR5
/dev/dsk/c7t0d0 /dev/rdsk/c7t0d0
disk 3 255/0/0.0.0.0 sdisk CLAIMED DEVICE DGC CX500WDR5
/dev/dsk/c8t0d0 /dev/rdsk/c8t0d0

[Patrick Wallek]

What do you mean "returns nothing"? Does it come back to the prompt? Do the pvcreate, then when it gets back to the unix prompt, do an 'echo $?' to see the return code. Is it 0 or 1 or something else?

What happens if you try a 'pvcreate -f /dev/rdsk/c8t0d0'?

[Scott Frye_1]

I tried pvcreate and pvcreate -f. When I say it returns nothing, I mean it never brings me back to a prompt.

[Pedro Cirne]

Hi,

Post here the following:

#diskinfo /dev/rdsk/c8t0d0
#diskinfo /dev/rdsk/c8t0d0

May be those devices are the "gatekeepers"..or the LUNs are locked, or not "enabled"...

Enjoy :)

Pedro

[Scott Frye_1]

# diskinfo /dev/rdsk/c8t0d0
SCSI describe of /dev/rdsk/c8t0d0:
vendor: DGC
product id: CX500WDR5
type: direct access
size: 10485760 Kbytes
bytes per sector: 512

[Devender Khatana]

Hi,

What does diskinfo report for this disk. The I/O to the disk can also bechecked by running dd on it.

Does dd goes fine?
What is the capacity of the disk?

HTH,
Devender

[Scott Frye_1]

What is dd?

[Devender Khatana]

Hi,

dd is the command to copy data from one device to another. Man dd for details.


HTH,
Devender

[Pedro Cirne]

Hi,

I guess this is an EMC Disk Array, probably the LUN is read-only or locked, you will need EMC help on this .-)

Enjoy :)

Pedro

[Devender Khatana]

Hi,

You can find out if your system can read the disk or not using

dd if=/dev/dsk/c8t0d0 of=/dev/null bs=1024K

And wheather you can write it or not by

dd if=dev/zero of=dev/dsk/c8t0d0 bs=1024K

HTH,
Devender

[Scott Frye_1]

# dd if=/dev/dsk/c8t0d0 of=/dev/null bs=1024K
dd: invalid number specification in option
# dd if=dev/zero of=dev/dsk/c8t0d0 bs=1024K
dd: invalid number specification in option

[Pedro Cirne]

Hi,

The LUN is locked or not enabled on the array side, I'm almost sure .-)

Enjoy :)

Pedro

[Devender Khatana]

Hi,

use k instead of K in the command.

HTH,
Devender

[Scott Frye_1]

Well a pvcreate I had running for about 1/2 an hour finally completed successfully. Doesn't appear to be a lock LUN, but the time it took to complete has me a bit concerned.

[Pedro Cirne]

Hi Scott,

If performance is too low, you should check if write cache is enabled on the disk array side, it's strange that it tooks half an our to do a pvreate...

Pedro

[Scott Frye_1]

Yes, write cache and read cache is enabled on the CX500

[Devender Khatana]

Hi Scott,

This indicates some problem if the pvcreate tokk so long. I would suggest reading the complete disk with dd and see how much it takes. It shall indicate the I/O rate as well. Another thing you could try is to create vg & file system on the disk and then mount it. Then copy some existing file system data to disk and see transfer rate.

#find /var -name "*" -print |cpio -pdmv /new_mount-point

Where your new file system is mounted at /new_mount-point.

But lokking at the symptoms I do not know how much time it will take to create the file system.

I suppose you use command line pvcreate only and not initialized media somehow which can run mediainit on the disk and could take this much time.

HTH,
Devender

[Scott Frye_1]

Devender,

I ran the dd right after you posted that I should use a lower case k instead of an upper case K. It still hasn't returned to a prompt.

Scott

[Devender Khatana]

Hi,

As it is reading the whole disk it may take a while. Reading a whole 10GB LUN could take a max. of 15-20 minutes. How long it took in your case to come back to a prompt?

Is there any improvement on this?

Regards,
Devender

[Scott Frye_1]

pvcreate took 30 minutes on 10 gig lun. EMC said they do not support iSCSI with HP-UX... has anyone done this before?

Scott