Actual Mirroring process checking ?

[Umang Bhavsar]

Is there anyway i can see how much mirroring is done on vg00 in background ? i want to compare resource for 2 way mirror and 3 way mirror.

Thank in advance.

[Helen French]

# lvdisplay -v /dev/vg00/lvol_name

This will tell you how much mirror has been done so far. The PEs on "stale" are still needs to be synchonized with primary disk. The one which is "current" has been finished already.

[A. Clay Stephenson]

You are going to get your best data by using Glance - io by disk. The answer to your question depends upon your scheduling policy for the LVOLS - parallel (best performance) or sequential. In most cases the overhead of mirroring is minimal although the system must wait for all the disks to update on physical writes but the reads are done using the disk with the shortest i/o queue so that read performance is improved with mirrors.

[Steven E. Protter]

So you are going to set up 2 mirrors, test performance, then 3 and test again.

I have yet to find an application for a third mirror except when I am moving around lvols. But, this script should get you the data you want.

See attachment.

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