[linux-lvm] Query on PE size

Kumar amit mehta gmate.amit at gmail.com
Wed Jun 5 02:07:28 UTC 2013


I see that a VG will set the default PE size to 4MiB, i.e.
4 * 1024 * 1024 = 4194304 
(Please correct me if I'm wrong)

# pvcreate /dev/vdc1
# vgcreate testvg /dev/vdc1
# vgdisplay
# vgdisplay testvg|grep "PE Size"
   PE Size               4.00 MiB <----

I see that :
   -->vp_def->extent_size = DEFAULT_EXTENT_SIZE * 2;

Where DEFAULT_EXTENT_SIZE is #defined to 4096
<snip from lib/config/defaults.h>
#define DEFAULT_EXTENT_SIZE 4096        /* In KB */
<snip from lib/config/defaults.h>

This means that the default extent size being set is 8192, but as mentioned 
earlier,the default extent size as reported by 'vgdisplay' is 4 MiB. So Can
someone please point me to the place where this conversion of 8192 into 4MiB
is taking place in the code ?


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