Can I use pvmove in a stripped volume?

[Fan Jiang]

Hi All,

Can I use pvmove on stripped volume or data?

Thanks.

[Steven E. Protter]

Probably.

IF you asked HP support you would be advised to be more cautious.

Backup up all filesystems in the logical volume, umount the filesystems, lvremove the logical volume and rebuild it.

There are those that have used pvmove(not me). Just don't try it without a backup.

I think it would be a good idea to umount any filesystems before you start(probably required).

From the man page:
pmove cannot be performed if the volume group is activated in shared mode.

pvmove attempts to carry all allocation policies to the target logical volume, it will probably want to stripe the target lv.


SEP

[Robert-Jan Goossens]

No,

A pvmove can be executed when having active access to data except for

The volume group is activated in shared mode (e.g. in a ServiceGuard environment).
Disk striping is being used. To verify that

the logical volumes on this disk are not striped, run pvdisplay -v on the disk in question to see what logical volumes are residing on it. Then run lvdisplay on the logical volumes and see what the value of "Stripes" is set to. If it is '0', then striping is not in place.

Regards,
Robert-Jan

[Robert-Jan Goossens]

Sorry refrase,

pvmove within a volume group Yes,

A pvmove can be executed when having active access to data except for

The volume group is activated in shared mode (e.g. in a ServiceGuard environment).
Disk striping is being used. To verify that
the logical volumes on this disk are not striped, run pvdisplay -v on the disk in question to see what logical volumes are residing on it. Then run lvdisplay on the logical volumes and see what the value of "Stripes" is set to. If it is '0', then striping is not in place.

without the same volume group NO.

Regards,
Robert-Jan.

[John Palmer]

No, because pvmove works by temporarily mirroring the volume and striping and mirroring is not supported.

If you try it you get the following error:
Operation cannot be performed because some of the data on the physical volume
is striped and striped mirroring is not supported. To enable data transfer for
a physical volume through mirroring/reduction, do not specify the striping
options (-i, -I) when creating logical volumes on that physical volume.

[Armin Feller]

# pvmove /dev/dsk/c5t14d0 /dev/dsk/c5t15d0

Operation cannot be performed because some of the data on the physical volume is striped and striped mirroring is not supported. To enable data transfer for a physical volume through mirroring/reduction, do not specify the striping options (-i, -I) when creating logical volumes on that physical volume.

So you need to backup the lvols data, recreate the lvol with the new disk and stripe it and restore the data, like Steven E Protter wrotes.

[Fan Jiang]

Actually, we want to migrate stripped data from a set of PVs to another set of PVs which is on a new array. We found out that online mirroring is not an option for stripped volumes. Now pvmove is out of the picture also. Is there any other ways we can migrate the data online?

[Tim Sanko]

I think this can be done. I believe it can done on a Symmetrix, with Online JFS. So do you have Online JFS?

and is the Volume able to be managed via Online JFS? ie not root volume...

Tim

[Fan Jiang]

Yes, online JFS is on. And it is a Symmetrix volume.

[Massimo Bianchi]

In such cases i always used dd.


create, on destination disks, an exact copy of the source lvols.

Then, umount them and for each lvol do

dd if=/dev/vgSOURCE/rlvolXXX of=/dev/vgTARGET/rlvolyyy bs=512k

if target and source vg are the same no problem.


The only drawback of my outlined solution is the requested downtime....

Massimo

[Fan Jiang]

Thanks Massimo.
One more question, if I want to get rid of stripe, can I create target lv with no stripe and do dd?

[Ashwani Kashyap]

pvmove will not work .

If you can get down time , create a target vg/lv with no stripes and the use cpio to migrate the data with find :
#cd $source_dir
#find . -xdev -depth | cpio -pdm /target_dir .

The only draw back is files greate than 2GB cannot be copied whith cpio , it has to be done manually .

[Massimo Bianchi]

Yes,
simply create the target lvol in a different way, with no stripe on them.

pay attention to use the Rlvol, otherwise the copy will be very much longer.
Before the real move, do some benchmark to test the best combination of parallelism in dd/ thoughput on the board, cpu cycles and so on..

With my solution there are no problem for the 2G/ not 2G issue :)

Massimo

[Tim Sanko]

If it is a symmetrix striped meta, not a ONLINE JFS meta, you alocate it and pvmove it.

If it is Online JFS Use dd as mentioned above.

You could also use RDF if you have EMC's ECC.
RDF could clone it itself...

Tim