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Increasing VG that is hosted by EMC Clariion

 
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Increasing VG that is hosted by EMC Clariion

HP-UX 11.23 attached EMC CX500

How do I extend a Volume Group after the LUN was expanded? I can see the full size in Diskinfo, but VG Display shows 0 extents available. According to EMC, I should not have to vgextend. The Storage Engineer said he added a MetaLUN.

SCSI describe of /dev/rdsk/c8t0d0:
vendor: DGC
product id: CX500WDR5
type: direct access
size: 629145600 Kbytes
bytes per sector: 512

VG Name /dev/vg01
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 8
Open LV 8
Max PV 16
Cur PV 1
Act PV 1
Max PE per PV 51199
VGDA 2
PE Size (Mbytes) 8
Total PE 51192
Alloc PE 51192
Free PE 0
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

current size is 409,592MB
Thanks!
Yesterday was the first day of the rest of your life
7 REPLIES 7
Pete Randall
Outstanding Contributor
Solution

Re: Increasing VG that is hosted by EMC Clariion

If you take a look at the vgextend man page, you'll see that it offers a way to enlarge the volume group by *adding physical volumes*. It doesn't say anything about physical volumes that magically increase in size.

You would be much better off to present new LUN's from your Clarion than to expand an existing one.


Pete

Pete

Re: Increasing VG that is hosted by EMC Clariion

Apparently, the Clariion Arrays have the ability to attach Meta LUNs together. I was wondering if anyone else out there in the "HP World" has done this.

The vgextend to new volumes is the method I have always done. However, the Storage Engineer is saying -"I made a MetaLUN for you...it should be there"

Yesterday was the first day of the rest of your life
Pete Randall
Outstanding Contributor

Re: Increasing VG that is hosted by EMC Clariion

And you should say to the storage engineer "Thanks for nothing because I can't use it. Next time check with me for my requirements before you arbitrarily decide to do something your way."


Pete

Pete
Chandrahasa s
Valued Contributor

Re: Increasing VG that is hosted by EMC Clariion

Hi Lawrence,
Find solution provided below:
Phase1(Backup)

Take backup of all mount points which are comes under VG01
********************************************************************
Phase2(unmount all mount points)

umount all mount points which are comes under vg01

umount /mountpoint
*********************************************************************
Phase3(Determining the pe value)

Yours vg01 max pe is 51199
Each pe size is 8MB

Yours total Lun size is 629145600/1024= 614400MB

Hence vg01 max pe should be 629145600/8=76800(can be taken as 80000)

so you first need to change max pe of vg01
***********************************************************************
Phase4(Changing max pe of vg01)

take backup of /etc/lvmtab-----cp /etc/lvmtab /tmp/newlvmtab_date
Take backup of /etc/lvmconf/vg01.map---cp /etc/lvmconf/vg01.map /tmp/vg01.map_date

vgmodify -e 80000 -n vg01---will take few minutes to complete
vgdisplay -v vg01---and conform max pe value
*************************************************************************
Phase5(Updating lun sizes in VG01)
vgmodify -E vg01 /dev/vg01 /dev/rdsk/c8t0d0 ------(/dev/rdsk/c8t0d0 is your disk device file)

vgdisplay -v vg01----conform free pe size

then you need to increase the lvsize as per your requirement
********************************************************************************
Chandrahasa s
Valued Contributor

Re: Increasing VG that is hosted by EMC Clariion

Hi lawrence,

In Phase5 i forgot to add this step:

befor doing:
vgmodify -E vg01 /dev/vg01 /dev/rdsk/c8t0d
Do:
vgchange -a n vg01
after vgmodify:
vgchange -a y vg01
Complete procedur attached.

Chandra
chris huys_4
Honored Contributor

Re: Increasing VG that is hosted by EMC Clariion

Hi Lawrence,

LVM on HP-UX 11.23 should allow for offline dynamic lun expansion (DLE), when the necessary patches are installed and if the diskarray supports the HP-UX 11.23 DLE features.

More info and procedures on how to execute offline DLE can be found on :
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01920387/c01920387.pdf (BSC link updated by admin)

Applied to your situation. (rip off of the procedure on page 20-22 of the above pdf docu.)

1. Check the current configuration with vgmodify in "review mode".

# vgmodify -r -v

Will show if LVM has recognized the change in size of the LUN. (from 400gb to 600 gb)

vgmodify will also do some checks if f.e. the current max_pe_per_pv value of the volumegroup is big enough to "accomodate" the new size of the lun.

In your case, the current max_pe_per_pv of volumegroup /dev/vg01, looks to be to small to accomodate the new LUN size and will thus need to be increased.

maximum pv_size of a pv of the vg = max_pe_per_pv * PE_Size = 51199 * 8 Mbyte = 409592 Mbyte < (629145600 kbyte / 1024 =) 614400 Mbyte (= new LUN size)

2. run vgmodify in "table" mode to find a suitable "max_pe_per_pv and max_pv " combination for the existing available LVM metadata space

# vgmodify -t -v

vgmodify -t -v will give a table with combinations of values for max_pe_per_pv and max_pv, that can use the existing LVM metadata space, that is available.

Else, you would need to free up physical extent 0, if its in use by a logical volume, with pvmove, and use that extent to "expand" the LVM metadata space. (see for more info the mentioned pdf docu)

Suppose the table specifies values, that will work with the new LUN size, in the current LVM metadata space, verify if these values are indeed ok.

3. verify the values found that should be applied to accomodate the new LUNsize with vgmodify in review mode.

# vgmodify -r -p -e -v

If vgmodify doesnt complain anymore.

Do the real changes.

4. Deactivate the volumegroup
# vgchange -a n


5. specify the new max_pv and max_pe_per_pv values which will allow the new LUN size to be fully used, with vgmodify, in change mode.

# vgmodify -p -e -v

6. Activate the volumegroup.

# vgchange -a y -s

7. check with vgdisplay -v if everything is ok.

Greetz,
Chris
chris huys_4
Honored Contributor

Re: Increasing VG that is hosted by EMC Clariion

Hi Lawrence,

You will not only hit the max_pe_per_pv value for volumegroup vg01 . What is not so bad as it can be adjusted, with vgmodify, as can be seen from my previous reply.

But what is worse, due to the PE size of 8Mbyte, you will also hit the hard limit of the maximum number of physical extents per physical volume that LVM allows, which is 65535, man vgcreate.

Or, with a PE size of 8 Mbyte, the physical volume can have a maximum size of, 65535 * 8 Mbyte = 524280 Mbyte, which is still smaller then the new LUN size of around 614000 Mbyte.

And with vgmodify it doesnt seem you can change the PE size to a larger size. So or have the storage engineer lower the lunsize again to around 524280 Mbyte, or the volumegroup will have to be recreated with a larger PE size, which will be able to "fit" a lun of around 600gb+.

For luns that are initially 100gb+ in size, I would at least use a PE size of 32 Mbyte, so that they can grow to max 2Tbyte luns.

As HP-UX 11.23 doesnt allow, even offline dynamic lun contraction, I would however be very careful, if you would opt for letting the storage engineer decrease the lunsize to "fit" "in the 65535 pe's", i.e. get a backup of the data of the volumegroup first, then deactivate the volumegroup, then let the storage engineer decrease the lunsize and then do the rest of the steps..

Greetz,
Chris