Disk group migration

[Prokopets]

Hi!
I'm dealing with hp-ux 11v3 and EVA8100 with temporary Business Copy license. EVA shows some LUNs to hpux from one disk group (lets call it DG_One). This LUNs are all in one volume group.
I added some enclosures with disks and created another disk group (lets call it DG_Two). So, the question is: how to move the LUNs from DG_One to DG_two with minimum downtime?
I have an approximate plan:
1) shutdown applications that are using the storage
2) unmount all filesystems on this LUNs
2.1) maybe, shutdown system?
3) make a snapclones of all LUNs, wait until it ends replication
4) unpresent all old LUNs
5) present new ones with old LUN ids
5.1) turn system on

I'm not sure if it's a good plan, and be happy if anyone criticizes it. Also, i've read this thread: http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1276277&admit=109447626+1252752400823+28353475 about problems of changing LUNs online and if anyone can comment it - it will also be very appreciated.

Philipp.

[P Muralidhar Kini · Accepted solution]

Hi Philipp,

Refer the following links for similar discussion -
http://forums11.itrc.hp.com/service/forums/questionanswer.do?admit=109447626+1274278296691+28353475&threadId=1321868
http://forums11.itrc.hp.com/service/forums/questionanswer.do?admit=109447626+1272100878798+28353475&threadId=1354054
http://forums11.itrc.hp.com/service/forums/questionanswer.do?admit=109447626+1273478940508+28353475&threadId=696657

Hope this helps.

Regards,
Murali

[Prokopets]

Thanks, Murali!
As i can see from this threads, the less complicated method is just what i wrote, but it means downtime at least until all LUNs will end snapcloning process. And i forgot about LUNs WWN, so my plan should look like this:

1) shutdown applications that are using the storage
2) unmount all filesystems on this LUNs
3) unpresent all old LUNs
4) make a snapclones of all LUNs with changing defauld WWname with the source LUN ones, wait until it ends replication
5) present new ones with old LUN ids

As for 2.1 - it looks like it's not mandatory in this case.

[P Muralidhar Kini]

Hi Philipp,

>> As i can see from this threads, the less complicated method is just what i
>> wrote
Yes, your set of steps does look optimized.
Lets see what other forum members have to say about this.

>> And i forgot about LUNs WWN
Yes right. The unique WWN for every target has to be maintained.

When you do eventually try out your plan, let us know how that goes.

Good luck.

Regards,
Murali

[Prokopets]

Well, i tried to do this migration on test FS, then on test database. Kernel doesn't like this procedure:
=====
#dmesg
.....
class : lunpath, instance 47
lun path (class = lunpath, instance = 47) belonging to LUN (default minor = 0x10) has gone offline. The lunpath hwpath is 1/0/6/1/0.0x50001fe15012c3ea.0x4006000000000000

class : lunpath, instance 38
lun path (class = lunpath, instance = 38) belonging to LUN (default minor = 0x10) has gone offline. The lunpath hwpath is 1/0/6/1/0.0x50001fe15012c3e8.0x4006000000000000

class : lunpath, instance 77
lun path (class = lunpath, instance = 77) belonging to LUN (default minor = 0x10) has gone offline. The lunpath hwpath is 1/0/14/1/0.0x50001fe15012c3e9.0x4006000000000000

class : lunpath, instance 83
lun path (class = lunpath, instance = 83) belonging to LUN (default minor = 0x10) has gone offline. The lunpath hwpath is 1/0/14/1/0.0x50001fe15012c3eb.0x4006000000000000

LVM: VG 64 0x010000: PVLink 3 0x000010 Failed! The PV is not accessible.
=====

Now oracle took his files and looks like my plan worked fine. Unfortunately with downtime...

[chris huys_4]

Hi Philipp,

> LVM: VG 64 0x010000: PVLink 3 0x000010 Failed! The PV is not accessible.

Your procedure is a shortcut of the procedure, I would use. I.e. I would try to avoid the above message.

>1) shutdown applications that are using the storage
>2) unmount all filesystems on this LUNs

I.e. After unmounting the filesystem, "vgexport preview, for the mapfile" followed by a "vgexport" of the volumegroup that contains the OLD lun.

> 3) unpresent all old LUNs
> 4) make a snapclones of all LUNs with changing default WWname with the source LUN ones, wait until it ends replication
> 5) present new ones with old LUN ids

Then vgimport the volumegroup with the "new" "old LUN ids".

NOTE: Would probably throw in a vgchgid before the vgimport, for safety.

NOTE2: Not to sure that after "your" step 5, dmesg wouldnt ask to execute a scsimgr replace_wwid to get access to the "new OLD lunid" lun.

> Now oracle took his files and looks like
> my plan worked fine. Unfortunately with
> downtime...
Thats why you have host (volumemanager) mirroring, which allows for online "migration"..

Greetz,
Chris

[Prokopets]

>>Thats why you have host (volumemanager) mirroring, which allows for online "migration"..

Chris, was it possible to use mirroring in my situation without MirriorUX installed?

Philipp.

[chris huys_4]

Hi Philipp,

> Chris, was it possible to use mirroring in
> my situation without MirriorUX installed?
No, it wasnt.

But mirrordisk/UX, is virtually something that almost cost nothing and also is included in most "environments", except the base OE, so the cost shouldnt be a prohibitive for any corporation, who can afford a hp-ux/oracle environment, imo. ;)

Greetz,
Chris

[Prokopets]

>the cost shouldnt be a prohibitive for any corporation, who can afford a hp-ux/oracle environment, imo. ;)

Chris, you live in a better world than i :)

Philipp.