vgcreate problem

[iambluegary]

i look man vgcreate:
vgcreate /dev/vg00 /dev/dsk/c1t0d0 /dev/dsk/c2t0d0
/dev/dsk/c1t0d0 /dev/dsk/c2t0d0 access to the same PV
which one determine the PV num? t0 or d0?

[James R. Ferguson]

Hi:

The PV NUM is determined by the order in which the alternate links are assigned. The primary (first assigned) would be PV(0); the secondary (alternate) link would be PV(1). The PVID would be identical for both disks.

Regards!

...JRF...

[Victor_5]

c# instance number of the interface card
t# SCSI target address
d# device number

Regarding your question, since you are using the same PV, the answer should be d#.

[Michael Tully]

Hi,

The numbering of disks depends upon the hardware addressing of the SCSI path. If you have two SCSI cards going to the same physical disk this is the type of information that will be reported.

c2t0d0
disk 0 on controller 2 (t0)

c= controller, referencing the controller on the system to which the disk drive is attached. Each disk controller will have a unique number.

t= target number. Each disk on a SCSI chain
will have it's own number.

d= disk device unit number

HTH
-Michael

[Sridhar Bhaskarla]

Hi,

As per the volume group whichever disk is configured first will be the first PV aka primary link and the other alternate. However you can change this behaviour anytime by using pvchange command.

Even if they are two different disks, the same explanation holds good.

So, the answer is neither t0 nor d0.

-Sri

[iambluegary]

does it mean that c2t0d0 and c1t0do are the different control cards that control the same PV ,in this case,PV is located on scsi 0 unit 0

[S.K. Chan]

Yes

[Michael Tully]

Yes that is correct.

[iambluegary]

but i find that in man vgcreate:
vgcreate -s 2 /dev/vg00 /dev/dsk/c1t0d0 /dev/dsk/c1t2d0

c1t0d0 c1t2d0 do not the same PV

[Michael Tully]

Hi,

When your creating a volume group it is best to
create the group first with one disk and then
add any additional disk secondly with the
vgextend command. This applies to whether it is
a disk mirror (alternate path) or any additional
disk.

How I would create a volume using the largest
volume I have available I plan for that group

# vgcreate -p 128 -s 2 /dev/vg01 /dev/dsk/c1t0d0
# vgextend /dev/vg01 /dev/dsk/c1t2d0
etc etc

~Michael~