LV size for BCV Operation

[V.P]

Dear All,

Server-IA 11.23 HPUX

The overall sequence of a backup is
1) Unmount fileystems in BCV server by deactivating the VG.
2) BCV is normally split
3) Few hours before backup,
sync up bcv of the system (host1 or host2...)
4) Check BCVs are synced
5)shutdown or coalese database to freeze activity
6) generate and tranfer vg/lv/fs info to BCV host
7) split bcvs
8)Bring up database on bcv host to make sure it works
7) bring database down and start backup
8) unfreeze/restart database on main host
9) once backup is done, mount all LV by activating the VG in BCV server.
10) keep bcv split until next cycle of backup.

Now the query is it mandatory to have same LV size in production and BCV server for syncing.
For eg:- production have one LV with 10GB with 5GB of data on that LV and BCV server has same name of LV with the size of 8GB….while syncing is it gives any error as the LV size is different but the 5GB data can hold by the LV in BCV server.
Thanks in advance for the answers.


reg

Jeevaraj

[johnsonpk · Accepted solution]

HI Jeevaraj,

>>Now the query is it mandatory to have same LV size in production and BCV server for syncing.

BCV is happening in storage on LUN level,means you can't have different size of LVs on either side of you BCV volumes .Even if you did some changes,it will be flushed out during the next BCV sync.

[V.P]

Hi Johnson,

Thanks for the confirmation,

exact requirement is for raw device in DB, meand LV without filesystem.

Production:- LV--test.dbf with 10 GB and having 5GB of database created on it.

BCV Server--LV-test.dbf with 8GB.
if am doing bcv syn from production to backup server, whether sync will successfully happen for this particular data file or not?

Thanks.

[johnsonpk]

Production:- LV--test.dbf with 10 GB and having 5GB of database created on it.

BCV Server--LV-test.dbf with 8GB.

How did you set the LV size ? It is created recently after last BCV sync? How u replicating your LVm info from Prod to BCV and how frequent is that?

nevertheless the BCV sync will not fail and LV size will reset to the production size after the sync.

However your Vg activation process on the backup server will fail if you have added any new LUN on the production side for creating the new LV

Bottom line : BCV is an actual copy process happening on the storage lun to lun ,each track/sector by track/sector and does not care about LVM layout

[V.P]

Hi Johnson,

am not going to add any new Lun's. will use the existing one only, but I want to just reduce the lvsize in BCV first then want to fire the bcv sync, as per my undrstanding, bcv sync doesn't have any business with data size and only checks the lun size and avaiabilty.

Appreciate other suggestions.

[Kapil Jha]

BCV syncs data sector wise so I suppose you would have to have exact copy as in production.

You can not reduce it.

BR,
Kapil+

[johnsonpk]

>> as per my undrstanding, bcv sync doesn't have any business with data size and only checks the lun size and avaiabilty.

You are right besides it does not realy care about what is there on the BCV volume (including data and lVm structure) during a sync . During sync everything from primary volume including data and lvm structure will be copied to BCV volume.If you are not convinced, go ahead and increace the size of one of the LV in the BCV volume (Size wil be set to the original LV size in primary volume)


BTW , You are the one who worked with HCL 2003 Batch??

regards!
Johnson

[Michael Steele_2]

HI

After you split the BCV's and have two identical mounted lvols you want to reduce the mirror?

I think you would end up with parity errors. You should be considering the affect you will have on the raid 5 standard dg and bcv dg and realize that they are no longer compaible with each other and hang on the next merge.

These dg's groups have to be exact in size or you will get parity errors.

[V.P]

Thanks to all, closing the same.