lvextend question.

[Juan Manuel López]

I have a lv and fs mounted.
I need to create a mirror using lvextend -m 1
Do I need to unmount fs to perform this lv extend ? Or can I make it while the fs is mounted.

Thanks in advance.

Juanma.

[Ian Dennison_1 · Accepted solution]

It should not need to be unmounted.

Confirm after perfoming an extend that the Lvol is on the disk you require it to be on, by perfoming an 'lvdisplay -v'.

Share and Enjoy! ian

[john korterman]

Hi Juanma,
you do not have to unmount in order to mirror an lvol, just do this:
# lvextend -m 1

where is the device name for the disk on which you want the mirror, e.g. /dev/dsk/c1t2d0

regards,
John K.

[T G Manikandan]

No.
Just do a

lvextend -m 1
i.e
#lvextend -m 1 /dev/vg05/lvol1 /dev/dsk/c0t5d0
check it with
# lvdisplay -v /dev/vg07/lvol5

THanks

[Ravi_8]

Hi,

If you are using Online JFS unmounting the fs is not necessary, otherwise need to unmount

[T G Manikandan]

sorry

lvdisplay -v /dev/vg05/lvol1

[Bill Hassell]

No, you do not need to unmount an active filesystem to mirror a logical volume. The mirroring software works at the raw disk level and knows nothing about whether this volume is mounted or active. The lvextend command starts a special driver process that performs 'atomic' synchronization, a fancy term that means: each extent written to the mirror will suspend any other writes until it has completed successfully. That means that each mirrored extent exactly matches the primary disk.

HOWEVER, this will create a huge load on the logical volume so on a busy system, any activity on this lvol will appear to be very slow until the mirroring has been completed. The same thing will happen with the lvsync command.