Upgraded two 3TB disks to two 4TB disks; each 4TB disk had 1TB free space about three weeks ago.

 

Now one 4TB disk has 500GB free, the other had 996GB free.

 

All of my shares use all disks, high-water, 50GB min free space, and split level 2.

 

Just thought each disk would be written to evenly, rather than what appears to be happening, one disk getting filled up and then the other.

 

Could be caused by WHAT you are writing...are they files that are constrained by the split level?

...also, no 'include' or 'exclude' settings, right?

 

The behaviour sounds correct got high-water allocation as a disk is used preferentially Neil it gets down to half the previous level.  If you want the disks to be used more evenly you should be using most-free as the allocation method.

 

As was noted depending on the path you are using, Split Level can constrain files to a particular disk.  Split Level takes priority over allocation method in event of conflict for a particular file.

Look at the description I put in the unofficial unRAID manual.

 

http://lime-technology.com/wiki/index.php/Un-Official_UnRAID_Manual#Allocation_method

 

Let us know if there is something you don't understand. Remember, it fils disk by disk so the highest number disk will be the last to "catch up".

 

As others have noted, the split level takes precedence. As an example, assume you start in the fall with single shows for each season. If you use a split level that keeps complete TV seasons on a single disk then the allocation method just might start all these new TV seasons on a single disk since that's the disk presently being filled. Once that happended then all the episodes go to that disk.