expanding filesystems in SAN

[jackie baron_1]

I have lots of HPUX experience but none with SAN. How do I modify (expand) filesystems that are part of a SAN system? Obviously in my experience if I wanted to expand a filesystem (in the traditional way) I would just unmount it and use the lvextend commands, etc. but with SANs I'm clueless.

Thnx

[Jorge Pons]

Hi

HPUX Version?
type of SAN?

Regards, Jorge

[Jorge Pons]

Hi

to explain for HPUX:

http://h30499.www3.hp.com/t5/LVM-and-VxVM/vgmodify-to-increase-PE-size/m-p/4150817#M31831

Regards, Jorge

[Torsten.]

If you talkabout file systems it makes no difference where they are.


Most SAN (in fact SAN based disk arrays) allow to expand LUNs. HPUX 11.23 and above can handle this, 11.11 cannot.
So you may consider to create another LUN, add the LUN to the VG, extend the LV and the file system.

[Ismail Azad]

Hi,

Adding to Torsten.... yes, it doesn't make much of a difference and since you are unmounting your file system.... looks like you have an FOE or BOE with Base JFS product and i guess by that etc. in your question you mean extendfs because an lvextend only extends the container of the filesystem that is your LV and not the filesystem itself.

Only thing that you would have to remember while working with a LUN is a quote from many documents "HPUX normally has no visiblility to the disks within a LUN"... I quoute that out of context since we are talking about LVM configuration, probably one of the few things notable while working with SAN and LVM in terms of configuration of LVM.

Regards
Ismail Azad

[jackie baron_1]

HPUX version is 11.23.

Have a file system that is 230Gb and need to make it 260Gb.

[Alzhy]

Jackie.. that is not enough info. Pls send:


bdf /mntpnt (of filesystem you wish to expand)

mount -p|grep mntpnt

vxlicrep


Expanding Filesystems in HP-UX on whatever type of disks is the same and only vary with what type of volume manager and filesystem you use.

Expanding LUNs (or Disks) is a different matter though.

[Bill Costigan]

Are you using LVM?

As far as I know, LVM does not support increasing the size of one of its Physical volumes. The SAN LUN is a PV to LVM.

Assuming the LUN was 50GB when added to the volume group, LVM will set it up as a 50GB disk. If you then increase the LUN size to 60GB on the array, HPUX will see it is now 60GB but LVM will still only be able to use the first 50GB. So with LVM you need to create a new LUN, add it to the volume group and then lvextend the logical volume which has the file system on it. You can do the with commands or use SAM or smh to extend the lvol and SAM and smh will also extend the filesystem.

If you are not using LVM and you created the filesystem directly on top of the LUN, then you can expand the LUN on the disk array and do and ioscan on HPUX. You should then do a diskinfo to verify that HPUX sees the new size.

You can then extend the filesystem using the vxfs commands. fsadm is one comamnd that will work but there are others.

[jackie baron_1]

Alziy,

Here is the data you requested:

adec12:/root#bdf /db/P2ZARDB
Filesystem kbytes used avail %used Mounted on
/dev/P2ZARDB/db 230948864 28248 229116624 0% /db/P2ZARDB


adec12:/root#mount -p|grep /db/P2ZARDB
/dev/P2ZARDB/db /db/P2ZARDB vxfs ioerror=mwdisable,largefile s,mincache=direct,delaylog,convosync=direct,dev=40100002 0 0
/dev/P2ZARDB/temp /db/P2ZARDB/temp vxfs ioerror=mwdisable,largefile s,mincache=direct,delaylog,convosync=direct,dev=40100004 0 0
/dev/P2ZARDB/arch /db/P2ZARDB/arch vxfs ioerror=mwdisable,largefile s,delaylog,dev=40100003

The FS needs to be expanded to 260 Gb.

[jackie baron_1]

Also

adec12:/root#vxlicrep

VERITAS License Manager vxlicrep utility version 3.02.006
Copyright (C) 1996-2004 VERITAS Software Corp. All Rights reserved.

Creating a report on all VERITAS products installed on this system

-----------------***********************-----------------

License Key = 3JZU-WDP6-PP6C-P4O4-HS38-NPPO-P
Product Name = VERITAS File System
Serial Number = 1
License Type = PERMANENT
OEM ID = 4095

Features :=
HP_OnlineJFS = Enabled

CPU Count = Not Restricted
Platform = HP-UX
Version = 4.1
File Change Log = Enabled

[Torsten.]

>>Assuming the LUN was 50GB when added to the volume group, LVM will set it up as a 50GB disk. If you then increase the LUN size to 60GB on the array, HPUX will see it is now 60GB but LVM will still only be able to use the first 50GB.



For exactly this reason there is the "vgmodify" command in 11.23 and 11.31. This will adjust the LVM structure so you can use the "full" 60GB in this case.

[Alzhy]

You have OnLine JFS and are using LVM. So You should be able to expand the filesystem by:

(1) Expanding the underlying PV and doing the gyrations.
or
(2) Have your Storage Admin present a new LUN/Disk and add it as a new PV to the LVM VG - which is the normal:
- pvcreate on new SAN Disk
- vgextend VGNAME newPV
- expand LV of Filesystem (lvextend)
- expand/adjust the filesystem (fsadm)

[jackie baron_1]

So Torsten,

why do I need to use the vgmodify command. The volume group is /dev/P2ZARDB:

vgdisplay /dev/P2ZARDB
--- Volume groups ---
VG Name /dev/P2ZARDB
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 4
Open LV 4
Max PV 64
Cur PV 4
Act PV 4
Max PE per PV 10240
VGDA 8
PE Size (Mbytes) 32
Total PE 7676
Alloc PE 7675
Free PE 1
Total PVG 1
Total Spare PVs 0
Total Spare PVs in use 0


the logical volume that need to be extended is:

lvdisplay /dev/P2ZARDB/db
--- Logical volumes ---
LV Name /dev/P2ZARDB/db
VG Name /dev/P2ZARDB
LV Permission read/write
LV Status available/syncd
Mirror copies 0
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 225536
Current LE 7048
Allocated PE 7048
Stripes 0
Stripe Size (Kbytes) 0
Bad block off
Allocation PVG-strict/distributed
IO Timeout (Seconds) default

Normally I would just do a vgextend, then lvextend then extendfs. But with this SAN stuff I don't really understand it. I have no clue about LUNs etc. Sorry for the practical "newbie" nature of this question.

[Torsten.]

Look at your settings:

Max PV 64
Cur PV 4
Act PV 4
Max PE per PV 10240
VGDA 8
PE Size (Mbytes) 32
Total PE 7676
Alloc PE 7675
Free PE 1


There is only 1 free PE, so you need more disk space.

You can

1) expand the existing LUN and adjust LVM with vgmodify to get more free PEs

or

2) create a new LUN (with maximum 10240 PE in size) and add it to the VG. For a larger new LUN you need to adjust the max PE per PV with vgmodify too.

[Alzhy]

You say that you have lots of HPUX experience. Surely you have added a disk to an LVM volume as part of your vast experience?

LUN==disk, they're practically the same.

With local SCSI disk though -- you only have ONE disk device. A SAN "LUN" (or disk) can have multiple disk devices -- in which you need to to vgextend your VG to however many disk devices a LUN has (this is called PV Links). On HP-UX 11.31, a peristent device (/dev/rdsk/diskNNN) will be present and representative of all your LUN's "diek devices" - so you need not boter about PVLinks. All the rest as it pertains to LVM gyrations is the SAME.!

In your case, I would suggest JUST adding a new LUN/disk and vgextend your LVM VG and expand the LVOL and filesystem on top of the LVOL...

What kind of SAN Disks do you have - this could spell other issues that you need to be familiar with and even give you an idea if LUN expansion is possible.

Cheers!

[Steven E. Protter]

Shalom,

Best strategy is to add additional LUN's, present them to the system and use vgextend (or the vxvm equivalent). HP-UX has consistent problems recognizing increases in existing LUNS.

sEP

[Torsten.]

>> HP-UX has consistent problems recognizing increases in existing LUNS.



Who is telling this?

[Alzhy]

I was about to ask the same question Torsty...

Amazing...

We've NetApps and EVAs and XP24Ks and we've never had issues with OnLine LUN resizing on HP-UX 11.23/11.31 and Linux.

[Torsten.]

This will help:

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01920387/c01920387.pdf

Using the vgmodify command to perform LVM Volume Group Dynamic LUN Expansion (DLE) and Contraction (DLC)