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Re: expanding filesystems in SAN

 
Torsten.
Acclaimed Contributor

Re: expanding filesystems in SAN

>>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.

Hope this helps!
Regards
Torsten.

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Alzhy
Honored Contributor

Re: expanding filesystems in SAN

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)

Hakuna Matata.
jackie baron_1
Regular Advisor

Re: expanding filesystems in SAN

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.
Acclaimed Contributor

Re: expanding filesystems in SAN

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.

Hope this helps!
Regards
Torsten.

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Alzhy
Honored Contributor

Re: expanding filesystems in SAN

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!
Hakuna Matata.
Steven E. Protter
Exalted Contributor

Re: expanding filesystems in SAN

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
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Torsten.
Acclaimed Contributor

Re: expanding filesystems in SAN

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



Who is telling this?

Hope this helps!
Regards
Torsten.

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Alzhy
Honored Contributor

Re: expanding filesystems in SAN

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.
Hakuna Matata.
Torsten.
Acclaimed Contributor

Re: expanding filesystems in SAN

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)

Hope this helps!
Regards
Torsten.

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