vgextend error - too many links

[mjos]

Hi, I am trying to create a new vg

vgcreate -p 32 /dev/vg_ap01 /dev/dsk/c10t0d1

When i extend this vg to another 15 disks I am getting the following error

vgextend: couldnt install the physicall volume /dev/dsk/...
too many links

Please help

[mjos]

vgdisplay output

# vgdisplay -v vg_ap01
--- Volume groups ---
VG Name /dev/vg_01
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 0
Open LV 0
Max PV 32
Cur PV 1
Act PV 1
Max PE per PV 4095
VGDA 2
PE Size (Mbytes) 4
Total PE 4095
Alloc PE 0
Free PE 4095
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0


--- Physical volumes ---
PV Name /dev/dsk/c10t0d1
PV Name /dev/dsk/c1t0d1 Alternate Link
PV Name /dev/dsk/c2t0d1 Alternate Link
PV Name /dev/dsk/c3t0d1 Alternate Link
PV Name /dev/dsk/c4t0d1 Alternate Link
PV Name /dev/dsk/c5t0d1 Alternate Link
PV Name /dev/dsk/c6t0d1 Alternate Link
PV Name /dev/dsk/c7t0d1 Alternate Link
PV Status available
Total PE 4095
Free PE 4095
Autoswitch On
Proactive Polling On

I am not able to add another 8 disks as alternate links to this vg

[VK2COT]

Hello,

You have reached the limit of
maximum physical volumes in the volume group.

To check it, run vgdisplay(1) of your volume
group and check "Max PV" and "Current PV".

If you run HP-UX 11.23, to enable vgmodify(1)
install patches PHCO_36744, PHKL_31500, and PHKL_32095.

If you run HP-UX 11.31, vgmodify is native in it.

Cheers,

VK2COT

[Bernd Reize]

you're using the PVLinks feature for path redundancy. PVLinks allows a maximum of 8 Paths per physical volume, the error message "too many links" means you already use all 8 possible paths (which is shown in your vgdisplay output, too).

For redundancy 8 paths nomally should be enough. Is adding more paths for this one volume really what you want to do or do you maybe want to add another volume instead?

[VK2COT]

Ahh, I did not see your follow-up with vgdisplay report.

A different problem. You are obviously
trying to add alternate links into the VG.

From the manual:

When a pv_path refers to one of the physical
volumes already in the volume group by a
different pv_path name to indicate the use
of a different controller, this new path
becomes an alternate link to the physical
volume. When two paths that reference the
same disk are provided in the pv_path list,
the order of the paths is important. The
first path becomes the "primary link" to the
physical volume, the second becomes an
"alternate link" to the physical volume. The
primary link is the path used to access the
physical volume unless the primary link
becomes unavailable in which case LVM
automatically switches to the alternate link
to access the physical volume (see WARNINGS
section). Currently LVM supports a maximum of
8 paths to a physical volume (7 alternates
and one primary).

VK2COT

[Torsten.]

Think about it!

You don't really need so much alternate links I guess.

Analyze your environment and think about what link and what order (!) makes sense as an alternate.

[mjos]

Thanks, I presented a 16gb LUN from the EVA for this VG. On the server side 16 disks got presented, all having the same wwn nos & the same size.
So I need to add all these disks to the same vg. Is that required or can I add just 8 disks. In future if I want to remove this VG, will all these 16 disks get unpresented from the server.
Also when I do a pvdisplay for the disk that is not added, it shows up as it is not a part of any VG

[Torsten.]

Accoring to your post you have only 1 (!) vdisk (LUN) assigned to this VG:

Cur PV 1
Act PV 1


All other links are alternate links to the same LUN:

--- Physical volumes ---
PV Name /dev/dsk/c10t0d1
PV Name /dev/dsk/c1t0d1 Alternate Link
PV Name /dev/dsk/c2t0d1 Alternate Link
PV Name /dev/dsk/c3t0d1 Alternate Link
PV Name /dev/dsk/c4t0d1 Alternate Link
PV Name /dev/dsk/c5t0d1 Alternate Link
PV Name /dev/dsk/c6t0d1 Alternate Link
PV Name /dev/dsk/c7t0d1 Alternate Link


In other words:
The LUN is the one and only (the same), but the pathes from the server to the LUN are different.

[mjos]

Is there any order in which I need to extend the VG
The luns I got from the EVA are

/dev/rdsk/c1t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-3/NonOptimized
/dev/rdsk/c2t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-3/NonOptimized
/dev/rdsk/c3t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-1/NonOptimized
/dev/rdsk/c4t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-1/NonOptimized
/dev/rdsk/c5t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-3/Optimized
/dev/rdsk/c6t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-3/Optimized
/dev/rdsk/c7t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-1/Optimized
/dev/rdsk/c8t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-1/Optimized
/dev/rdsk/c9t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-4/NonOptimized
/dev/rdsk/c10t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-4/NonOptimized
/dev/rdsk/c11t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-2/NonOptimized
/dev/rdsk/c12t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-A/FP-2/NonOptimized
/dev/rdsk/c13t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-4/Optimized
/dev/rdsk/c14t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-4/Optimized
/dev/rdsk/c15t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-2/Optimized
/dev/rdsk/c16t0d1 5000-1FE1-5010-9D90 6005-08B4-0006-AD3E-0000-8000-05B9-0000 16384MB Ctl-B/FP-2/Optimized

I did pvcreate on /dev/rdsk/c10t0d1
After that I am trying to extend the vg to all the other disks

[Torsten.]

Again:

Analyze your environment and think about what link and what order (!) makes sense as an alternate.


What makes sense?

First path

HBA1 - switch1 - EVA CtrlA

second path

HBA2 - switch2 - EVA CtrlB

From now on it really depends on your hardware layout and your needs.