Comment # 17 on bug 1006952 from zhen ren

(In reply to Ladislav Mate from comment #15)
> Hello, 
> sorry for delay. I might found why lv_var was displayed exactly 5 times for
> vg00/lv_var and reason is LV was extended several times and its Segments are
> spread to 5 physical locations on PV. I've tried to --uncache vg00/lv_root
> and output is same also for vg00/lv_root and LV is shown 4 times as LV is
> split in 4 Segments. So I performed 'sudo pvmove --alloc anywhere -n
> /dev/vg00/lv_root /dev/sda /dev/sda' to tighty LV to one Segment, and after
> another --cache & --uncache operation is all OK. Same applies also for
> vg00/lv_var which looks normal now and it's displayed only once. If I split
> LV to more segments again LV is display multiple times. 
> 
> If you feel that this is OK , feel free to close this bug.

Hi Ladislav,

This issue can be replicated easily as below:

tw1:~ # vgcreate vgtest /dev/vdb1
    Volume group "vgtest" successfully created
tw1:~ # lvcreate -L 3G -n lv1 vgtest
    Logical volume "lv1" created.
tw1:~ # lvcreate -L 3G -n lv2 vgtest
    Logical volume "lv2" created.
tw1:~ # lvextend -L +1G vgtest/lv1
    Size of logical volume vgtest/lv1 changed from 3.00 GiB (768 extents) to
4.00 GiB (1024 extents).
    Logical volume vgtest/lv1 successfully resized.
tw1:~ # lvs -o+cache_mode
    LV   VG     Attr       LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync
Convert CacheMode
    lv1  vgtest -wi-a----- 4.00g                                                
    lv1  vgtest -wi-a----- 4.00g                                                
    lv2  vgtest -wi-a----- 3.00g

***while***

tw1:~ # lvs -o+cache_total_blocks
    LV   VG     Attr       LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync
Convert CacheTotalBlocks
    lv1  vgtest -wi-a----- 4.00g                                                
    lv2  vgtest -wi-a----- 3.00g     

This is by design, because "cache_mode" is under "Logical Volume Segment
Fields", every fields in this category will be displayed per "segment" as
you've pointed out. See:

tw1:~ # lvs -o help
        Logical Volume Device Status Fields
    -----------------------------------
...
      cache_total_blocks     - Total cache blocks.
...
    Logical Volume Segment Fields
    -----------------------------
...
      cache_mode             - For cache, how writes are cached.
...

So close as INVALID. Thanks for your report and contribution!