topic Re: PE LIMITS in Operating System - HP-UX

PE LIMITS

Kwahae_1 — Wed, 04 Jun 2008 20:27:56 GMT

Hi,

I have attached a display of one of my VG groups. My application using this VG just stopped working due to some reason. Someone suggested that I can no longer write files over 80MB to or extend this VG as its nearly exceeding its PE limits. Is is so and if yes is there any patches I can use to change VG attributes?

Thanks

Re: PE LIMITS

Kwahae_1 — Wed, 04 Jun 2008 20:31:31 GMT

Sorry I forgot to attach the file.

Re: PE LIMITS

Tim Nelson — Wed, 04 Jun 2008 20:38:05 GMT

the vgmodify command was introduced with a patch to 11.23 ( you did not specify what OS version you are using ).

max_pe and max_pv only apply to adding disk devices to the volume group. If your addition will exceed the value(s) then you will either not be able to add additional devices or use the full capacity of the device.

Writing files is a filesystem function and really has nothing to do with the volume group unless you are referencing the fact that the filesystem is full or does not have more than 80GB of configured capacity and you wish to add additional disk devices to the volume group.

The simplest way to repair this is 1 of the following

1) create a new VG with new disk, migrate the data off the old and replace with the new
2) create a new VG with new disk, choose a mount point that represents the majority of data in your filesystem, migrate that directories data to the new mountpoint, remove the old data and mount the new mountpoint at that directory or create a symlink to the new directory.

3) if you are using later versions of HPUX you could attempt to use the vgmodify command, there is a number of steps that need to be taken along with some data shuffling. I find it less stressfull to do a data migration to new VGs.

Cheers,

Re: PE LIMITS

Tim Nelson — Wed, 04 Jun 2008 20:44:25 GMT

Here is what you have.

Max PE per PV is 46,080 PEs (or about 737GB per device)

You current have 3 devices in this VG. All devices have all PEs allocated except 5 ( or 80MB) on the last disk.

I would.....

Add another disk/lun to this VG using the vgextend command.

then either lvextend this new space to an existing lvol and extendfs or create another lvol and newfs it and mount it somewhere.

You are no where close on maxing out this VG. Add some more storage.

Re: PE LIMITS

TTr — Wed, 04 Jun 2008 21:46:30 GMT

> Someone suggested that I can no longer write files over 80MB

I hope they meant that you have unallocated disk space of 80GB on the SAN disks

> extend this VG

You can extend the VG, you just need the disk space

> exceeding its PE limits

You did not exceed any limits. You used up all (except 80GB) of your disk space.

Now let's make something clear. The 80GB is unallocated disk space on your SAN disks.

What about the 3 oracle logical volumes, oralv1, oralv2 and fnlv1. Do they have any unused space? Are they raw volumes or do they have file systems on them?

Re: PE LIMITS

Kwahae_1 — Wed, 04 Jun 2008 22:27:39 GMT

Using hp-ux B.11.11 U 9000/800 and enclosed is my bdf display.

Re: PE LIMITS

Fabien GUTIERREZ — Thu, 05 Jun 2008 06:44:43 GMT

first of all your application cannot stop working because of a PE size. PE size can only be optimized for some applications but cannot make app stop. san disconnection can make application stop.
the max pe per pv limit only applies to a single lun
the cross product between the max pe per pv and the pe size give you the larger fs you can build in this vg

Re: PE LIMITS

Torsten. — Thu, 05 Jun 2008 07:35:07 GMT

Please carefully read this:

--- Physical volumes ---
PV Name /dev/dsk/c32t0d0
PV Name /dev/dsk/c34t0d0 Alternate Link
PV Name /dev/dsk/c36t0d0 Alternate Link
PV Name /dev/dsk/c38t0d0 Alternate Link
PV Status available
Total PE 11518
Free PE 0
Autoswitch On

PV Name /dev/dsk/c32t0d2
PV Status available
Total PE 3199
Free PE 0
Autoswitch On

PV Name /dev/dsk/c32t0d1
PV Name /dev/dsk/c34t0d1 Alternate Link
PV Name /dev/dsk/c36t0d1 Alternate Link
PV Name /dev/dsk/c38t0d1 Alternate Link

Some alternate pathes are missing, right?
Correct this soon!

You have only 5 free PEs now - this will limit your possibilities to extend anything.

File sizes and PE sizes are not really related, so I doubt about this:

"I can no longer write files over 80MB"

BTW, this is what I get from vgdisplay on my system:

#vgdisplay -v vg00
--- Volume groups ---
VG Name /dev/vg00
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 8
Open LV 8
Max PV 16
Cur PV 2
Act PV 2
Max PE per PV 4350
VGDA 4
PE Size (Mbytes) 8
Total PE 8682
Alloc PE 8682
Free PE 0
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0
VG Version 1.0
VG Max Size 556800m
VG Max Extents 69600

Have a look at the last lines.
Nice, isn't it (11.31)?

;-)