My question is how full does everyone else let the hard drives in their arrays get?  I have been trying to cram as much data as possible on each drive and wondered if, at some point, the drive could be too full and mess with parity checks or the like.

Years ago, I was told to leave 10% of a drive free on my Macs. Don't know if there's any data to back up this being a good thing, but it's always seemed to make sense for a standard desktop/laptop that's writing lots of files.

 

For the drives in my unRAID – 2Tb and 1.5Tb - leaving 10% would just seem a waste of space. And most of my files are 'write once, read seldom'.

 

My rule of thumb has been to leave roughly 1% – 20Gb or 15Gb free min. Haven't seen any problems on the drives I've filled so far.

 

But would be interested to hear of any scientific data on optimum space to leave.

I have been leaving 2% due to years of windows defragmenting warnings.  Which equals about 30GB on 2 TB drives.

My question is how full does everyone else let the hard drives in their arrays get?  I have been trying to cram as much data as possible on each drive and wondered if, at some point, the drive could be too full and mess with parity checks or the like.

It has no impact on parity checks, but it does not leave space for data migration/recovery efforts if you need to use some file-system repairs.  I also like to leave 15 to 20 Gig free on disks.  (enough to move at least one or two movies around) 

 

 

I always leave at least 2X the size of the largest file on the disc.  For reason's similar to Joe L (moving a file around, data recovery, etc.).