Increasing VDisk on EVA4400 (HPUX 11.11)

[Sheldon Smith]

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@Torsten. wrote:
Be careful, if the vdisk is extended already now, a shrink may or may not destroy your data!

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Don't see how. The 11.11 LVM was/is never able to make use of the extra vdisk space.

[Torsten.]

Well, if you (by accident) extend a let's say 101GB LUN to 150GB and then shrink to 100GB, this could IMHO really destroy your LVM and filesystem structure and data.

There was also a problem with shrink in eva firmware version 10000000, right? Need to lookup the details ...

[Mauro Livi]

Torsten...puzzled by the comment "...Don't see how. The 11.11 LVM was/is never able to make use of the extra vdisk space.."

Look at my vgdisplay below...only have 120 Free PEs available (just under 4GB). That's why I wanted to extend the VG...hence add another vdisk. Am I missing something?

--- Volume groups ---
VG Name                     /dev/vg02
VG Write Access             read/write
VG Status                   available
Max LV                      255
Cur LV                      7
Open LV                     7
Max PV                      16
Cur PV                      4
Act PV                      4
Max PE per PV               50000
VGDA                        8
PE Size (Mbytes)            32
Total PE                    28792
Alloc PE                    28672
Free PE                     120
Total PVG                   0
Total Spare PVs             0
Total Spare PVs in use      0

[Mauro Livi]

Sorry...the comment mentioned above was made by Sheldon, not Torsten. In any event, I was still puzzled by it.

[Torsten.]

I also doubt if i understand Sheldon's comment.

The problem with 11.11 is as follows.

LVM creates a physical to logical extend relation on a physical disk or LUN.

If the disk/LUN is now "growing", LVM needs to create more physical extends on the additional space.

While 11.23 and 11.31 have "vgmodify" to adjust this, 11.11 has no official way to do this, hence LVM cannot use the additional space until the VG is re-created.

So as we already know now, adding a disk/LUN is the way to extend a VG.

@Sheldon: The link you sent is not public, is it?

[Sheldon Smith]

Sorry. My point was, Mauro expanded the EVA virtual disk, but 11.11 was never able to expand the file system (by way of the volume group) into that extra space. If the system could never write there, there can be no data to lose. Right?

Possible Actions:

Consider returning the vdisk back to its original unexpanded size. Did you add a lot, or can you afford that much lost space?

Create and add a new up-to-225 GB vdisk.

Consider upgrading HP-UX to 11.31?

I will assume the PVs in the group were all 225 GB? Certainly if you shrink to less than the size the LVM had recognized for the LUN, you will lose data. I don't remember the firmware version(s) that had problems shrinking.

@Torsten - Oops. That was not a public link. Cutting and pasting between too many text windows.

[Mauro Livi · Accepted solution]

Sorry if I mislead anyone. I haven't done anything...i.e. have not added any vdisks nor have I extended any VG (yet).

I will need to extend a VG and I had simply read that if I increase my vdisk size, there is no way to modify the VG at HPUX11.11 other than recreating it. This was verified by Torsten. Therefore, the better solution for me would be to:

1) Create a new vdisk

2) vgextend the VG that needs more space and lvextend any lvol on that VG.

Again, sorry if I confused anyone...and thanks for all your input.

Mauro

[Stuart Powell]

If you have mirroring in place I believe you can break the mirror, remove the PV from the VG, delete the VG, "recreate" the PV, and  then add it back into the VG. Then the new size will be recognized. I haven't done this in quite a while but I believe that is the process that will work.

[Stuart Powell]

If I recall the process is:

1. Break the mirror(s) for the lvol’s (lvreduce)
2. Reduce the PV from the VG (vgreduce)
3. Re-create the PV (vgcreate –f)
4. Add the PV back into the VG (vgextend)
5. Re-add the mirror(s) (lvextend)