Am I confused/mis-understanding something? Am I thinking of a different field? Or is this a bug? (Actually, even if I’m confused, I feel there IS a bug here.)
THE ISSUE:
MINIMUM FREE SPACE for a share
unRAID 6.12.3
Drives in share formatted with xfs
HISTORY
I used a 3rd party backup program to back up my home PCs. I have the backup program (Macrium Reflect) write the backup files to a share on my unRAID server.
YEARS AGO, I had the backup program write each backup as one big file. This caused issues – if unRAID started to write to drive 1 of the share, and that drive only had 1TB free, and the backup file ended up being 1.5TB, the backup would fail due to running out of free disk space on that drive since the one big file could not straddle two physical drives (even if both drives are in one share).
I WAS TOLD to do two things:
1) Tell my backup software: Write the backups out in “chunks” (CHUNK is my word for it, that’s not the technical term!). I chose 250GB (yea, I played it overly conservative, bigger chunks would probably be easier to keep track of!).
2) Tell unRAID: Use the MINIMUM FREE SPACE field to tell unRAID to NOT write to a disk within a share if that disk has less than xxGB free – instead pick another disk in the share to write to. This way, no matter what unRAID allocation method was used (high-water, most-free, fill-up) and no matter what the disk size, unRAID would not try to put what MIGHT be a huge file onto an almost full drive. I think I did 500GB (or was it 1TB? Either way, I gave myself extra “elbow room” over-and-above the “chunk size” of 250GB)
This worked great for years.
THE PROBLEM DETAIL:
I recently upgraded to unRAID 6.12.3. Not sure if this issue started with this version or an earlier version. Since the backups have been working OK, I have not looked at that share definition in a long time.
I just now looked at the share definition that holds my backups. The MINIMUM FREE SPACE field now has a percentage, not an absolute number. I tried changing it back to a number:
500GB. I hit enter, and it changes that number to 500000000 (a.k.a. 500,000,000), just like it used to. But then it changes it to a percentage!?!? And the percentage does not make sense (to me).
This share is made up of 4 physical drives:
12TB (currently 1.3TB free)
12TB (currently 2.6TB free)
6TB (currently 2.81TB free)
16TB (currently 15.2TB free)
I put 500GB (or 500 GB) in the MINIMUM FREE SPACE field, and unRAID eventually turns it into 25.6%
I don’t see ANY situation using ANY of those numbers above (max individual size, total size, free size) where 25.6% equals 500 GB!?!?
If I put in 1000GB (also tried 1tb or 1TB or 1 tb or 1 TB), it expands the number to 1000000000, but then it changes it to 51.2%!?!?!? So is that saying if the entire share is more than half full, a file will not be written? Or if an individual drive is more than half full, a file won’t be written to that drive? That makes no sense at all – 1TB does NOT equal 51.2%!?!?
Is this simply a formatting error of how that field is displayed? How can I be sure what the actual value is? Or is unRAID actually doing a bad calculation?
FYI - In the attached diagnostics, the share that I'm working with is named: UR-BU-i9
BUT I tried some other shares and they are also showing a similar issue - MINIMUM FREE SPACE is being converted to a weird percentage.
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