[CentOS] strange usage stats for thin LV

Sun Nov 11 14:53:12 UTC 2012
Vitaly Yakovenko <mr.yaky at gmail.com>


I have the problem with fstrim (thin provisioning).

some details:

uname -a
Linux test.local 2.6.32-279.14.1.el6.x86_64 #1 SMP Tue Nov 6 23:43:09 UTC
2012 x86_64 x86_64 x86_64 GNU/Linux

/dev/mapper/VolGroup00-lv_root on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/md0 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
/dev/mapper/VolGroup00-lv_test1 on /mnt/test1 type ext4 (rw)
/dev/mapper/VolGroup00-lv_test2 on /mnt/test2 type ext4 (rw)
/dev/mapper/VolGroup00-lv_test5 on /mnt/test5 type xfs (rw)

df -h
Filesystem            Size  Used Avail Use% Mounted on
                       20G  2.3G   17G  13% /
tmpfs                 1.6G     0  1.6G   0% /dev/shm
/dev/md0               99M   27M   67M  29% /boot
                       40G  2.6G   35G   7% /mnt/test1
                      4.0G  1.2G  2.6G  32% /mnt/test2
                      3.0G  725M  2.3G  24% /mnt/test5

lvs -a -o+metadata_percent
  LV                VG         Attr     LSize   Pool      Origin Data%
 Move Log Copy%  Convert Meta%
  lv_native         VolGroup00 -wi-a---   5.00g

  lv_root           VolGroup00 -wi-ao--  20.00g

  lv_swap           VolGroup00 -wi-ao--   4.00g

  lv_test1          VolGroup00 Vwi-aotz  40.00g thin_pool         27.73

  lv_test2          VolGroup00 Vwi-aotz   4.00g thin_pool         98.61

  lv_test5          VolGroup00 Vwi-aotz   3.00g thin_pool         45.40

  thin_pool         VolGroup00 twi-a-tz 100.00g                   16.40
  [thin_pool_tdata] VolGroup00 Twi-aot- 100.00g

  [thin_pool_tmeta] VolGroup00 ewi-aot- 100.00m

This test server (CentOS 6.3 - not install from scratch). I was updated
this server from 6.2 version:

last | tail -3
reboot   system boot  2.6.32-220.el6.x Mon Jan 23 16:03 - 16:04  (00:01)
wtmp begins Mon Jan 23 16:03:26 2012

I test only ext4 fs partitions.
When I used fstrim I had next error:

fstrim /mnt/test1
fstrim: /mnt/test1: FITRIM ioctl failed: Operation not supported

I want retrieve free space from the ext4 fs to the total free space of
thin_pool after delete files on the ext4 fs  (lv_test1).I will have more
free space for another thin LV.
Is it possible to get it?

Thanks in advance.