It seems the LUNs you have created almost consume 80%+ of the total volume capacity. Have you used Snapshot or installed any Apps? It seems you have tried accessing the NAS through SSH, have you checked the volume for shares or possible log files that consumed the space? Also, having fragmentation on the volume, defragging it will move data around and might show different space allocations /infoirmation.
As always, we advise as much as possible to allocate more than 20% of your total storage for other processes/services (Snapshots,Apps, logs, copies) small to no space allocated for these might degrade the performance and also the space accounting of your NAS. 80% of usage may seem to be too low but it usually is just the right amount to be considered as max to avoid any performance and accounting issues
Are you experiencing any performance degradation or any issues on your connections? It is best to contact Support and have them check it on the backend since you are also using LUNs.
Other users might be able to suggest for steps on what to check and what to do.
It seems the LUNs you have created almost consume 80%+ of the total volume capacity.
Based on the first post, @Jota79 has 24 TB of space in two volumes (12 TB each), and 16 TB of LUNs - which would be 67%. That assumes the LUN size is in TB - if it is TiB, then the space used should be about 73%.
@Jota79: do you have 4 LUNs on each volume? How full is each volume (per the Web UI?)
Re: ISSUE - Unallocated/free space Volume DECREASING with no reason
No snapshots:
root@Netgear-rn4220:~# btrfs subvolume list -s /VOLUME_PERFORMANCE2
root@Netgear-rn4220:~# btrfs subvolume list /VOLUME_PERFORMANCE2 ID 257 gen 2028563 top level 5 path .purge ID 258 gen 2028563 top level 5 path .vault ID 259 gen 2104228 top level 5 path NOSUP_VOL02_LUN01 ID 260 gen 2102113 top level 5 path ._share ID 2310 gen 2104228 top level 5 path ARA_VOL02_LUN01 ID 4359 gen 2104228 top level 5 path NOSUP_VOL02_LUN02 ID 6408 gen 2104228 top level 5 path NOSUP_VOL02_LUN03
Re: ISSUE - Unallocated/free space Volume DECREASING with no reason
No snapshots:
root@Netgear-rn4220:~# btrfs subvolume list -s /VOLUME_PERFORMANCE2
root@Netgear-rn4220:~# btrfs subvolume list /VOLUME_PERFORMANCE2 ID 257 gen 2028563 top level 5 path .purge ID 258 gen 2028563 top level 5 path .vault ID 259 gen 2104228 top level 5 path NOSUP_VOL02_LUN01 ID 260 gen 2102113 top level 5 path ._share ID 2310 gen 2104228 top level 5 path ARA_VOL02_LUN01 ID 4359 gen 2104228 top level 5 path NOSUP_VOL02_LUN02 ID 6408 gen 2104228 top level 5 path NOSUP_VOL02_LUN03
Sorry - a line break in your du post led me down the wrong path there. You might want to use the </> tool as it often formats lists like this better. Here's a reformatted one with a couple of blank lines added:
