Mirror logical volumes

[Sentinel_2]

Hi All,
I have to migrate to new storage (from EVA to EVA).
I will use lvextend -m to mirror the lvol´s between disks of the two cabinets but I was wondering if I can run several lvextend -m at the same time (at different shells)
Will I save time if I do it in this way? Anyone knows the transfer rate for 1 Gb, more or lees?

Thanks

[Torsten.]

The operations will set a lock, so you can only mirror one at a time.

[johnsonpk · Accepted solution]

prior to Hp ux 11.31 sept 2007 it is not possible

Even if multiple commands are run in parallel, LVm locking
mechanism forces them execute one at a time (you may notice a message ""cannot lock /etc/lvmconf/lvm_lock still trying.." )


But in Hp ux 11.31 sept 2007 or later you can do it parallel by the below approach

lvextend -s -m 1 (note the -s option)
lvextend -s -m 1
lvextend -s -m 1

once you done with lvextend

lvsync -T
lvsync -T
(Note : -T option This option resynchronizes the specified logical volumes in parallel rather than serially)

[johnsonpk]

What is you OS version?

[johnsonpk]

What is your OS version?

[Sentinel_2]

I have two different O.S. versions, 11.11 and 11.23

[johnsonpk]

No luck :-(

You need to go with one at a time as Torston suggested.

[Sentinel_2]

OK Thanks for your quick answers; does anyone have an idea of how long can take to mirror the lvols? Let´s say per Gb.
A couple of minutes per Gb?

[TTr]

> does anyone have an idea of how long can take to mirror the lvols?

It all depends how fast your interfaces to the array are and how much i/o the array groups you have created can handle.

You could try a read test on one of the logical volumes that you are going to mirror to see how fast you can read it.

dd if=/dev/vgXX/lvolYY of=/dev/null bs=1024k count=5000

This will read 5GB from a volume in a similar manner that the mirroring process would do.

You have to factor the write time to this as well. You could also try a write test to the target logical volumes.

Of course the mirroring will be impacted by the remaining server i/o activity and server load but you will get a rough idea how long the process might take.

[Torsten.]

Since mirroring is online, you don't need to worry about the time. No downtime is needed.

Just mirror all the LVOLs, then remove the mirror from the old EVA.

You can make a small script for all the mirroring, so the mirrors will be created one by one without any additional input required.

Just let it run.