lvextend

[balaji_vvv]

I have question in mirroring a Jbod which has 6 disk drivers and i split the bus and now
each controller have 3 disks.

I have created a filesystem (3 disks) with controllerA.
Now when i want to mirror controllerA disk with Controller B (3 disks). I did the following steps.
pvcreate /dev/rdsk/c1t1d0 /dev/rdsk/c1t2d0 /dev/rdsk/c1t3d0
vgextend vg01 /dev/dsk/c1t1d0 /dev/dsk/c1t2d0 /dev/dsk/c1t3d0

lvextend -m 1 /dev/vg01/lvol1 /dev/dsk/c1t1d0 /dev/dsk/c1t2d0 /dev/dsk/c1t3d0

Now question is, since i have 3 disks i have to give lvextend -m 3 .... or whatever i gave (lvextend -m 1) is correct?

[Torsten. · Accepted solution]

-m 1 is correct, you want to have 1 mirror copy of your data on 3 disks, not 3 mirror copies.

[balaji_vvv]

Thank for the fast response, So 1 or 3 indicates no. of mirror copies.

[balaji_vvv]

m indicates no. of mirror copies.

[Cinoj]

As you have 3 disks to be mirrored with another set of 3 disks, the number of mirror copy is 1.

I just wanted mention that, using PVG will be helpful here.

Ref: http://docs.hp.com/en/B2355-60103/lvmpvg.4.html