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Showing posts from July 23, 2017

LVM thin provisioning - file system usage and pool usage dosn't match

When I was demonstrating LVM thin provisioning to new batch of campus hires ; they pointed out an important mismatch between thin pool usage and actual file system usage.

I thought , it would be worthy to give it a try to find the cause.

So here we go; I created a thin pool with size of 100MB and thin volume of 1GB

Thin volume formatted with ext4 and mounted over /test_fs

Everything was going smooth as per the plan until we did a tar backup of /usr over /test_fs.

Here we go ;

* Created vg001 - size 12GB

[root@ol7-san ~]# vgdisplay vg001   --- Volume group ---   VG Name               vg001   System ID   Format                lvm2   Metadata Areas        1   Metadata Sequence No  12   VG Access             read/write   VG Status             resizable   MAX LV                0   Cur LV                0   Open LV               0   Max PV                0   Cur PV                1   Act PV                1   VG Size               12.00 GiB   PE Size               4.00 MiB   Total PE              3071   Allo…