So over the last day or two my Cache drive has been seeing an increase in data being written to it. Currently the UI and Grafana both say that 230GB are being used:

 

Yet when I go into /mnt/cache and do a du I only see 187GB being used:

 

Any ideas where this discrepancy is coming from and where the data actually is? I even did a scrub recently.

Edited March 26, 20215 yr by TheLaughingMan

If possible before rebooting and preferably with the array started
Go to Tools - Diagnostics and attach the complete Diagnostics ZIP file to your NEXT post in this thread.

Here you go, I have not touched anything

skynet2.0-diagnostics-20210325-0921.zip

Part of it is the differing units (GB vs GiB) between what the dashboard says (500GB drive) vs the commands (465GB drive)

 

du --si will give a larger value, and the rest is probably taken up by metadata storage 

 

 

That puts it close to 200, so is 30GB of metadata realistic?

du isn't accurate with btrfs, what the GUI shows is the correct space used, if you have Windows vdisks there see this.

22 hours ago, Squid said:

Part of it is the differing units (GB vs GiB) between what the dashboard says (500GB drive) vs the commands (465GB drive)

 

du --si will give a larger value, and the rest is probably taken up by metadata storage 

 

 

So using the calculate option on the share tab, I am not seeing any significant growth on any share that uses my cache yet my cache drive utilization has gone up 10GB since my initial post. Any clue what causes that?

Do you have vdisks?

Yes but nothing in /domains is growing

It's growing but it's not being reported, like mentioned if they are Windows VMs see the link to enable trim, if other OSes see if you can do the same, for a temporarily solution you can copy the vdisks with cp --sparse=always, then delete old one(s).

That makes sense now, apparently it was the linux VM I host servers on. Doing that cp --sparse=always 'freed' up 30 GB

Note that it will still continue to grow with use.

Yeah but at least I know the cause and I am no longer paranoid. I can look into implementing something similar as you pointed out for windows or bake into my weekly back up to just copy it and replace old version (Aka the dumb lazy way if I can't figure out the proper way)