What disk data is mirrored to

[Travis Harp_1]

I'm currently engaged in a project to migrate data from one EMC frame to another.
We are using a method of creating devices on the new frame, vgextend'ing them into the volume groups, lvextend -m 1 to the new devices then vgreduce the old devices.

I'm at the point where I need to vgreduce the volumes but since these systems are live while doing this I would like a reliable way to confirm that none of the data I mirrored ended up disks that I'm about to vgreduce (because if that happened then I would reduce out both the original and the mirror).

Is there a quick and simple way to confirm that all the data ended up where I wanted it to go?


Thanks,
Travis

[melvyn burnard · Accepted solution]

use lvdisplay -v to show where the copies lie:
lvdisplay -v vgxx |more

[Patrick Wallek]

Do an 'lvdisplay -v /dev/vg??/lvol??' for each of the LV's that you mirrored.

This will tell you what physical extents each logical extent occupies and on which devices.

[Tim Nelson]

If the old device is still part of an lvol then the vgreduce will fail as the device is still in use. ( do not force it )

pvdisplay -v /dev/dsk/old-disk

The only output should be that it is still a member of the vg. No lvextents should be mapped to anything.

I have done the same process a number of times to migrate from old array to new. Works great !! Non intrusive !! Pretty much fool proof.

[Travis Harp_1]

Ok this confirmed my fear that some of the data ended up on one of the disks I plan to reduce.

What would be the best method for moving the data to the correct disk?

Can I simply change the mirror count to 0 thus removing the mirror and remirror that lvol to the correct device?

[Patrick Wallek]

Yes.

# lvreduce -m 0 /dev/vg??/lvol?? /dev/dsk/c?t?d?

where the /dev/dsk/c?t?d? is the disk you want to remove the mirror from.

When you do the lvextend you should also specify a specific disk device to put the mirror on. This way you are sure where it is going initially.

# lvextend -m 1 /dev/vg??/lvol?? /dev/dsk/c?t?d?

[sathish kannan]

Travis,

Did you consider using SRDF for data migration from one EMC frame to another?

Regards
Sathish

[gold_21]

Hi travis,

You can use also Open Replicater from EMC, I found it easier than SRDF. it is like cloning but out of the box, you will need only the target disk WWN and the source disk WWN. No need for bin file change or Symconfigure.

Regards,

gold_21