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Presentation of VDISK to another node

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Christian Marquardt_1
Regular Advisor

Presentation of VDISK to another node

Hello,
we've a two node cluster connected to a eva3000 storage array and putting the database backup to a vdisk on the eva3k. it is possible to present the vdisk with the backup to another node connected to this eva3k in read only mode which is not a member of this database cluster?

regards
Christian
9 REPLIES
Luk Vandenbussche
Honored Contributor
Solution

Re: Presentation of VDISK to another node

Hi,

I don't know what OS version you are running.
But in HPUX it is perfectly possible.

You present it to the host.
Import the VG and activate it with readonly option

vgchange -a r /dev/vgxx
Christian Marquardt_1
Regular Advisor

Re: Presentation of VDISK to another node

Hi Luk,
thanks for the answer.
The cluster machines running hp/ux 11.0 on pa-risc.
The machine to which I'll present the vg in read only mode running a hp/ux 11.23 on itanium.
I hope the different processor architecture is not a problem.

regards
Christian
Luk Vandenbussche
Honored Contributor

Re: Presentation of VDISK to another node

Christian,

I never connected it to a different architecture, but my experencies says me that it might not be a problem.

Perhaps you can try with an simple lun to see what the impact will be
Ivan Ferreira
Honored Contributor

Re: Presentation of VDISK to another node

This is a interesting solution, but I'm a little afraid about doing that. You may corrupt your disk if you forget to import/mount as "read only".

Do you have the Business Copy EVA license? I think that is safer to take a snapshot and present the snapshot to the other host.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Christian Marquardt_1
Regular Advisor

Re: Presentation of VDISK to another node

Hi Ivan,
using business-copy is a good idea too. I'll looking for a license and try it if I can.
Anyway ... because of that the cluster nodes contain our production databases I know that there's a risc but I can "recover" this vdisk by doing a new full backup if the files are corrupted.
Thanks for your answer.

regards
Christian
Uwe Zessin
Honored Contributor

Re: Presentation of VDISK to another node

I don't think you can do that. Don't have a CV-EVA session handy right now, but if I remember correctly, the readonly setting is on the virtual disk, not an individual mapping to a host.

And even if it were possible, then *I* would not do it.

The reason is that the read/write host is still able to make changes to the disk and it's meta data. The 'readonly' host does not expect such changes and can run into file system inconsistencies which might even cause a system crash!!

That's one of the reasons for doing a snapshot or a clone.
.
Christian Marquardt_1
Regular Advisor

Re: Presentation of VDISK to another node

Hi Uwe,
thanks for your answer. These are very important reasons. I think I can't realize my idea this way.
What about umount-ing the vdisk from the db-cluster and mount it readonly to the other note? This is very easy because there are only the backup files on the disk.

regards
Christian
Ivan Ferreira
Honored Contributor

Re: Presentation of VDISK to another node

Your last option Christian is very save. You can do that.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Ivan Ferreira
Honored Contributor

Re: Presentation of VDISK to another node

Forgot to add, you should ensure that is dismounted before mounting in the other host. You can also unpresent the vdisk to have more security. You can do all using sssu scripts.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?