big problem...but difficult!

[Emanuele_4]

Hi everybody...this is a big question but it's related to critical systems and production environment...so I'm looking for an answer only if somebody is very very sure! ;-)

I'm not sure at all! :-(

Here the question:

EVA6000 with command view eva
Brocade switch.
Server itanium hpux 11.23

1) the initial situation:
on the EVA6000 I built a lun of about 17GB and presented it to 2 servers....for a cluster.
So, the 2 servers can see the shared disk like c4t0d0...diskinfo of c4t0d0 is 17GB. I built a vg...with c4t0d0 and at the end...the VG has 17GB of allocable space (3 lv...all ok)

2) the stupid error:
Somebody asked me to enlarge the lun!
I'm a stupid...because I run command view eva and enlarged the lun!!! the Lun now is 77GB!
the 2 servers still see the disk (lun) like c4t0d0...but obviously, the vg is still 17GB.
BUT diskinfo c4t0d0 is....77GB
So, the lun (I still see it like c4t0d0) has changed dimension...but the vg is still the same as before.

The question....I tryed to enlarge the vg but it's impossible (I HAVE NOT to loose data! So, no pvcreate!)...so...I'll build a new lun of 60GB...vgextend the existing vg(17GB) and voila...the vg will be made by 77GB using 2 lun (the 17old one and the 60new one).

Apparently no problem...but I'd like to reduce the initial LUN!!!

Command view EVA permitted me to enlarge the lun (17BG->77BG)...but I know the eva put data across many disk from itself but if I want to reduce it (77GB->17Gb)...is the EVA able to do it?
How can eva reduce lun dimension without loosing data? Is it possible?

Command view EVA permit to change lun dimension (increasing e relocating)...but I'm not sure it permits to reduce (it should relocate again...but without loosing data!).

So the question is:

Is it possible to reduce a lun without loosing data on it? (with EVA6000)

Points for anyone who have a granitic answer! ;-)

Thanks in advance to anybody!

Emanuele

[Ivan Ferreira · Accepted solution]

Comman View EVA does NOT allow you reduce the size of a VDISK.

Maybe you can:

Create a new vdisk.

Use LVM to mirror your current LVs to this new vdisk.

Split the mirror.

Remove the wrong sized disk from the VG.

Remove the disk in command view.

[Emanuele_4]

Thank you very much for your answer.

The last question.

I understand I can't reduce the lun so...I still will have the bigger lun.

Will have I any problem for this configuration?

a 77GB lun...a cXtYdZ disk of 77GB
BUT
a 17GB VG on the 77GB PV
?

I loose a lot of space...ok...but no problem for this..I only need the system is ok!

PS At the end...I did this error on 2 lun...the 17GB one and a 500GB one!
for the 17GB...I resolved...I created another one...copied data..and remove the old one.
but for 500gb...I'm thinking to keep the 500-520 lun with 500VG....I'm loosing only 20Gb...no problem if it works fine! ;-)

Thanks again

Emanuele

[m saravanan]

There is no issues, in keeping the LUN size bigger than the actual PV size. Only thing is, u can't use that space.

HP is working on this issue to enhance the LVM capability to increase the PV size on the fly. we may expect "pvextend" command :)


Regds,
Saravanan

[Emanuele_4]

Wow....If a new lvm version will have anything like "pvextend"...I'll more than happy! They don't imagine how many hours people will save! :-)

Thanks to all...byby

Emanuele