On Thu, May 10, 2018 at 07:30:09PM +0000, John Hamilton wrote: > I saw something today that I don't understand and I'm hoping somebody can > help. We had a ~2.5TB thin pool that was showing 69% data utilization in > lvs: > > # lvs -a > LV VG Attr LSize Pool Origin Data% > Meta% Move Log Cpy%Sync Convert > my-pool myvg twi-aotz-- 2.44t 69.04 4.90 > [my-pool_tdata] myvg Twi-ao---- 2.44t > [my-pool_tmeta] myvg ewi-ao---- 15.81g > > However, when I dump the thin pool metadata and look at the mapped_blocks > for the 2 devices in the pool, I can only account for about 950GB. Here is > the superblock and device entries from the metadata xml. There are no > other devices listed in the metadata: > > <superblock uuid="" time="34" transaction="68" flags="0" version="2" > data_block_size="128" nr_data_blocks="0"> > <device dev_id="1" mapped_blocks="258767" transaction="0" > creation_time="0" snap_time="14"> > <device dev_id="8" mapped_blocks="15616093" transaction="27" > creation_time="15" snap_time="34"> > > That first device looks like it has about 16GB allocated to it and the > second device about 950GB. So, I would expect lvs to show somewhere > between 950G-966G Is something wrong, or am I misunderstanding how to read > the metadata dump? Where is the other 700 or so GB that lvs is showing > used? The non zero snap_time suggests that you're using snapshots. I which case it could just be there is common data shared between volumes that is getting counted more than once. You can confirm this using the thin_ls tool and specifying a format line that includes EXCLUSIVE_BLOCKS, or SHARED_BLOCKS. Lvm doesn't take shared blocks into account because it has to scan all the metadata to calculate what's shared. - Joe _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
