title: LVM thinpool shrink
body: <p>I want to shrink a thinpool but don't manage to do it.
  Have some a procedure for that ?</p>
  <p>Here is some information:</p>
  <pre><code>hyper $ sudo lvs
    LV       VG  Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
    mailer   lxc Vwi-aotz--  64,00m pool        32,81
    nginx    lxc Vwi-aotz-- 512,00m pool        26,66
    pool     lxc twi-aotz-- 180,00g             2,29   11,45
    vpn      lxc Vwi-aotz--  64,00m pool        33,40
    [...]
  
  hyper dev $ sudo vgs
    VG  #PV #LV #SN Attr   VSize   VFree
    lxc   1  15   0 wz--n- 180,00g    0
  
  hyper $ sudo lvreduce -L100G /dev/lxc/pool
    Thin pool volumes lxc/pool_tdata cannot be reduced in size yet.
  </code></pre>
  <p>Is it possible to reduce the size of a thinpool ?<br />
  If needed, I can copy all the data elsewhere and then restore it, but how to do it properly ?</p>