Dne 31.10.2012 01:04, Andres Toomsalu napsal(a):
Hi,
I'm a bit puzzled with some thin LV usage stats - hope that someone can shed a light on this.
lvs shows that thin_backup LV is 94% used - but df shows only 16% - where comes the difference?
lvs -a -o+metadata_percent
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert Meta%
pool VolGroupL0 twi-a-tz 1,95t 35,17 2,79
[pool_tdata] VolGroupL0 Twi-aot- 1,95t
[pool_tmeta] VolGroupL0 ewi-aot- 14,00g
root VolGroupL0 -wi-ao-- 10,00g
swap VolGroupL0 -wi-ao-- 16,00g
thin_backup VolGroupL0 Vwi-aotz 600,00g pool 94,51
thin_storage VolGroupL0 Vwi-aotz 600,00g pool 20,98
df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroupL0-root
9,9G 1,3G 8,1G 14% /
tmpfs 16G 0 16G 0% /dev/shm
/dev/sda1 1008M 122M 835M 13% /boot
/dev/mapper/VolGroupL0-thin_storage
591G 39G 523G 7% /storage
/dev/mapper/VolGroupL0-thin_backup
591G 90G 472G 16% /backup
Thanks in advance,
As Stuart posted values are not related closely together.
But there are few things which are visible:
~35% tells you the number of used space in the pool - around ~700GB
~3% metadata takes - ~400MB
thin_backup has provisioned ~95% -> ~570GB
thin_storage ~21% -> ~130GB
which seem to match approximately number of used blocks from the pool
(~570 + ~130 = ~700)
===
Now to interpret your 'df' stats:
thin_storage uses 39GB stored in provisioned 130GB
thin_backup uses 90GB stored in provisioned 570GB
and there could be multi reasons for this:
- usage of large chunksize - and filesystem spreads a lot of data though the
device - either for it's internal maintenance, or a lot of files are located
across whole provisioned space.
- You have delete lots of files - and have not used discard for deleted areas
(i.e. for ext4 there is 'fstrim' command which will discard them)
So here you need to provide more information which filesystem is in use,
and what was the overall usage for your devices. And also are you using
discard support or not ?
What is the kernel version in use?
(It's always worth to use latest version of lvm2 - since there was improved
discard support configurability.
Zdenek
_______________________________________________
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/
