Can somebody help me understand BTRFS space?

[5footbanana]

I have a cache pool of two disks in BTRFS Standard RAID1.  I've just run a balance and I get this:  

Data, RAID1: total=84.00GiB, used=83.20GiB
System, RAID1: total=32.00MiB, used=16.00KiB
Metadata, RAID1: total=1.00GiB, used=76.62MiB
GlobalReserve, single: total=19.69MiB, used=0.00B

When I run 

 btrfs fi show /mnt/cache

I get the ouput:  

Label: none  uuid: (OMMITED)
        Total devices 2 FS bytes used 83.27GiB
        devid    1 size 232.89GiB used 85.03GiB path /dev/sde1
        devid    2 size 232.89GiB used 85.03GiB path /dev/sdf1

And in the unraid GUI it shows that I have used 89.4GB.  

  

However, I know for a fact that I only have approximately 69GB used on the cache disks (this is checking the sizes of the shares in windows and in unraid).

 

Where have I lost approx 20GB??

[JorgeB]

17 minutes ago, 5footbanana said:

And in the unraid GUI it shows that I have used 89.4GB.  

And that's correct:

83.27GiB = 89.4GB

[5footbanana]

1 minute ago, johnnie.black said:

And that's correct:

83.27GiB = 89.4GB

 

Yeah I get that bit is correct however my main question really is that I only have approx 69GB used on the shares but unraid and btrfs are saying 89GB.

[JorgeB]

Maybe you have something on the root of the cache, that would be outside the shares, also If you have vdisks cor other sparse files they an can grow and the usage be misreported, in any case the used space reported by the GUI is the correct one, and the space actually used.

[5footbanana]

55 minutes ago, johnnie.black said:

Maybe you have something on the root of the cache, that would be outside the shares, also If you have vdisks cor other sparse files they an can grow and the usage be misreported, in any case the used space reported by the GUI is the correct one, and the space actually used.

Okay cheers.

It's super annoying aha!

 

I've checked the root of the directory and nothing is there.

 

I have a single 50GB VM which i'm pretty sure isn't a sparse disk (it's always been 50GB in size).  I have a 10GB docker and then app data.  In Krusader it says i've used 85GB on the cache mnt too.  However the three shares on the root when I browse them are only using 64GiB.  Any other ideas?  I'm not too fussed about the lost space it's more I can't understand why!

[5footbanana]

Okay, so I moved the VM off the cache using mover.  I moved a 50GB file and I went from 85GB used to 20GB used.  With the remaining two shares taking up 15GB.

[5footbanana]

I just moved the file back, now I have 75GB used on my cache (14GB less than before).  I don't understand the discrepancy?

 

The files and shares are identical as before but unraid and btrfs are showing different values, is it something weird with the file system chunks?

[JorgeB]

See here to "re-sparsify" the file:

https://forums.unraid.net/topic/51703-vm-faq/?do=findComment&comment=557606