Hello, I am hoping to have someone sanity check me on whether or not these numbers make sense or not. As can be seen in the screenshot, I have 7 cache disks of varying size. Sometimes the cache pool will says 2TB total, but sometimes it will says 2.3TB. The USED and FREE numbers don't add up to anywhere close to 2 or 2.3 TB.

 

Most recently, I deleted my cache pool and completely reformatted all the drives, thinking that may solve the problem, however, it currently shows that of 2.3TB, I have 3.56MB used, and 1.27TB available. Another interesting note is that the bars seem to indicate that 3.56MB ~= 1.27TB.

 

From trying to look into this problem, I understand there's an issue with free space calculations in btrfs, but this all just seems a little off considering that I don't recall having an issue like this before and wanted to get some other eyes on it.

 

Thanks in advance!

trminator-diagnostics-20201230-1158.zip

btrfs raid1 with an odd number of devices gives incorrect free space, and it will change as you fill it up, that's a known btrfs bug, total size e used space should be correct, strange about the pool size.

BTW, total usable space will be 2.25TB

Thanks for the info. JorgeB! Though it makes me wonder, why include the Free Space at all if it's known to be buggy and there's nothing Unraid can do about it? Seems to me that the cache always has at least a good idea of how much space is actually being used, so it seems like it would look much better if there was only the used metric there, and if the bar filled up as a percentage of the used space over the calculated space (2TB/2.3TB in my case). Even if the total drive space does fluctuate a bit, 3MB/2.3TB vs 3MB/2TB or 200GB/2.3TB vs 200GB/2TB seems like it would look much better than an arbitrary 3MB ~= 50%.

 

While I haven't dug into creating plugins personally, does this seem like the kind of thing that could easily be done with a plugin? Seems likely to me. If so, perhaps I'll have a go at creating one.

Not something I can see a plugin being able to fix.    There has been work going on to get a proper fix applied at the generic linux BTRFS driver level and that is the sensible long term solution.   Btrfs has been getting better at reporting sensible values but it is not there yet  

I wasn't insinuating it would be a long-term fix, I was just thinking maybe a little javascript to clean it up a bit. I honestly don't know anything about Unraid plugins and what they're capable of.

45 minutes ago, bamhm182 said:

I wasn't insinuating it would be a long-term fix, I was just thinking maybe a little javascript to clean it up a bit. I honestly don't know anything about Unraid plugins and what they're capable of.

I do not see where anything could easily be hooked into the UnRAID GUI to ‘fix’ this issue which I’d why I did not think a plugin is going to help.    I think we are just going to have to wait until the Linux kernel developers finally fix this issue at the btrfs driver level and Unraid picks up the fix as part of its normal migration to newer Linux kernel releases for new UnRAID releases.

Fair enough. I'll take your word for it. Thanks for the additional information!