LVM shared mod

[Ivajlo Yanakiev]

Is it possible to extend LV in shared mod ?

[Steven E. Protter]

Can you add a few more details.

Is this a shared lvol as in a logical volume that is part of a volume group that ServiceGuard fails over between nodes.

If so its possible, but you need to be careful.

Please add some details.

SEP

[Ivajlo Yanakiev]

I want to extend online raw LV.
I use ORACLE RAC.

[Simeon Harwood]

Yes it's possible to extend the lvol in shared mode. Because its a raw lvol, you will have no control over the data on it from the HPUX level, so to be sure that your data is safe, I would use somthing like RMAN from Oracle to backup the data first, to make sure that it's safe. I would always suggest that you backed up data before doing anything like this.
After extending the lvol, you will need to make sure that the other machines that see the shared lvol get this info that it has been extended. To do this, I would export the vg in preview mode (as you would with a service guard cluster) and import it onto the other nodes.

e.g
on node 1 run this: -

vgexport â p â s â m\ vg01 /etc/cmcluster/maps/vg01

get the mapfile to node2 and run this: -
vgimport â s â m /etc/cmcluster/maps/vg01 vg01

Ho

[Simeon Harwood]

Sorry the previous text got corupted, should have read this: -

vgexport -p -s -m\ vg01 /etc/cmcluster/maps/vg01

vgimport -s -m /etc/cmcluster/maps/vg01 vg01

[Nguyen Anh Tien]

Impossible.
Only Vg is possible.
use "vgchange" to change mode
#vgchange -c y -S y /dev/vg01

[Duncan Edmonstone · Accepted solution]

From the manual 'Using Serviceguard Extension for RAC' ( http://docs.hp.com/en/T1859-90017/ch03s02.html#cegbaeff ) :

No configuration changes are allowed on shared LVM volume groups while they are activated. The volume group must be deactivated first on all nodes, and marked as non-shareable.

So no you can't - previous posters are talking about standard serviceguard (non SLVM) volumes.

HTH

Duncan

[Ivajlo Yanakiev]

HI Duncan

Is there any workaround ?
My service is 24/7 and I can not stop packets.

Do not tell me that I buy servers unix oracle
RAC and I can not extend LV :(

Do I am lose ?

[Duncan Edmonstone]

Yes its true - what most admins of RAC systems with SLVM do is define lots of unused raw lvols at cluster creation time, then you can just assign them as required. The other way out is to:

a) if you are using a RAID array, ditch the volume manager completely and just use raw disks, with all the implications of that...

b) Use Veritas CVM instead of LVM (basically clustered version of VxVM) - although I'm fairly sure this will cost $$$

HTH

Duncan

[Ivajlo Yanakiev]

Can I extend online Veritas volume ?
without stop pachets ?

[Ivajlo Yanakiev]

Doncan
coud you tell my what kind of problem I can have if I use raw LUNs (RAID) without LVM ?
for Oracle data ?

[Duncan Edmonstone]

Well the main problem is that you can't resize a raw LUN - if you want to make a tablespace bigger, you would need to add a new LUN instead...

I would seriously consider Veritas CVM to do this - it does allow you to make changes online.

HTH

Duncan

[Ivajlo Yanakiev]

Ok probably you are right but any way I will test it.
Thanks for now :))

[Ivajlo Yanakiev]

could you give me some point or documents where I can read that kernel do not support online LUN extend ?