Recently a 2008 R2 file server reached the 90% full mark on a non-OS data partition, and it started telling people with accounts on the server that they can't save anymore files. I do not have quotas enabled so I do not know where this message was coming from.
After looking at this a little more, it is unclear why "10%" is a fixed minimum space value, while as technology improves, disk space is soaring up from the old 2-32 gigs per server drive on up into the terabytes. On a new server, the "10% free" requirement is often bigger than the entire disk storage I had on servers about 8 years ago.
So on a 1 TB drive, below 100gb free is a "critical space event"? That sounds ridiculous.
Is there a way to adjust that down, so the server will only freak out and prevent people from saving in their accounts, if the drive is 98% full? On a 1 TB drive, this still means there would be 20 gig free on the drive, which is still a huge amount of free space.
Also when I built the system a couple years ago, I put the OS on another drive, and this other drive with 10% free is all account data only... So getting down to even 500 meg free should not cause OS problems, as far as I can tell.
,
On a related note, it seems the volume shadow copy service (VSS) used for open-file backups also flips out if free disk space gets too small. Though what is defined as "too small", is entirely unclear, since VSS does not seem to actually report
to me how much storage it is using, but just that "Error! Not enough disk space! I quit!" when I run a backup.
I can't tell if this is because VSS actually needed all that free space for caching, or if it hit the arbitrary 10% free and gave up without even trying to function normally.
On the 270 gig partition with only 10% free, I went into the disk properties, to the Shadow Copies tab, and set the Maximum Size to just 5 gigabytes. Windows did not complain about this.
After moving off another 50 or so gigabytes, the backup succeeded, no VSS errors, so apparently 5 gigs is not restrictive enough to cause a problem for VSS's operation?