[linux-lvm] unexpected behaviour of "lvresize" with sparse volumes

Chris Friesen chris.friesen at windriver.com
Wed Oct 14 20:18:41 UTC 2015


I'm running the 3.14 kernel with lvm 2.02.98 and I ran into something unexpected 
with lvresize.

I created a sparse volume:

lvcreate -L 25M -V 50M -n sparsevol myvg

This gives output in lvdisplay like this:
   LV Size                52.00 MiB
   Current LE             13
   COW-table size         28.00 MiB
   COW-table LE           7

I then resized the volume with lvresize:

lvresize -L 200M myvg/sparsevol

This seems to resize the COW-table, but not the volume itself.  Now lvdisplay shows:

   LV Size                52.00 MiB
   Current LE             13
   COW-table size         200.00 MiB
   COW-table LE           50

At this point I've got 200MiB of backing store and running "lvs" shows an LSize 
of "200m" but I can only write 52MiB worth of data to the volume before it 

Is there a way to expand the "LV Size" shown in lvdisplay so that I can write 
the resized amount of data to the volume?


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