Andy T

So in case anyone else comes here I have reduced it down to 628gb of "Other" on 110tb of disk. I've determined (using a blank disk) that the root cause is the checksums for ReFS metadata. See https://learn.microsoft.com/en-us/windows-server/storage/refs/refs-overview I can reduce it using NTFS, but I prefer ReFS for integrity. I know that is a controversial topic but I've made my choice, I'm happy with it and over many years of using ReFS with DriveBender I haven't had a problem. Big thanks to Shane and Christopher for offering suggestions.

It's not VSS. I'm exporting a list of every file and it's size to Excel so I can do some maths to see how much spaces is wasted due to the 64k block size. I have a File Placement rule that *.nfo files (which are mostly the files < 64kb) are all on 2 drives which are formatted for 4k clusters. Hopefully using Excel I'll be able to clarify the root cause.

Thanks for all the info Shane. I'm trying to force the only small files, which exist in a single folder to go onto a pair of drives formatted with 4k clusters, but I'm battling with the Balancer vs File Placement rules settings. I'm now up to 71tb of data and 469gb of Other!

Thanks Shane. Once you point it out thats pretty obvious actually! I still can't account for Other. Even using TreeSize there is nothing else on the disks. I am using 64k clusters but it feels unnaturally high to be the wasted space/in-efficiency of 64k for small files, given that most of the files are multi-gb.

I'm just in the process of switching from DriveBender to DrivePool. As of this this screenshot I had added: 1 x 1tb hard disk 1 x 8tb hard disk 1 x 256gb SSD So theoretically the most data that I can store with duplication is 1.2tb. So how did DrivePool manage to duplicate 1.9tb? And what is the 54gb of "Other"? These 3 disks were formatted before being joined to DrivePool. I know that Windows may put some things in System Volume Info behind the scenes, even if the disk doesn't have a drive letter... but 54.5gb?

My oldest remaining drive is a 1tb Western Digital WD10EADS Caviar Green, it's been powered on for 5069 days 21 hours or 19 years! It's lived through being in a RAID5 array, Windows Home Server Pool, Drive Bender and now DrivePool! I did have some 1tb IBM drives too only 1 out of 4 of those failed, the other three I simply removed to make space for newer/bigger disks. ROCK SOLID! I don't have may 4tb drives - I did, but they failed very quickly! Some got swapped under warranty, then failed again. I seem to remember a bit of a scandal, not the performance SMR one... but a design flaw or something. Have you looked at the data BackBlaze publish? https://www.backblaze.com/b2/hard-drive-test-data.html