More to consider wrt sorted I/O requests.  If I fill a partition
by creating a large file, delete the file and attempt to create
another large file in its place, the delayed deletion operation
causes the second creation to fail.

$ pwd
/storage/scratch
$ dd if=/dev/zero of=bigfile bs=1024k count=200 
200+0 records in
200+0 records out
209715200 bytes transferred in 8.326 secs (25187989 bytes/sec)
$ rm bigfile 
$ df 
Filesystem  1K-blocks     Used     Avail Capacity  Mounted on
/dev/wd0a       63248    31634     28451    52%    /
/dev/wd0e      253615    83672    157262    34%    /var
/dev/wd0f     1465278   372914   1019100    26%    /usr
mfs:123         31727     2175     27965     7%    /tmp
/dev/wd0g     1018329    56420    909297     5%    /home
/dev/wd0h    12766536 11862460    265748    97%    /storage
$ dd if=/dev/zero of=bigfile bs=1024k count=200 

/storage: write failed, file system is full
dd: bigfile: No space left on device
60+0 records in
59+0 records out
61865984 bytes transferred in 2.729 secs (22669836 bytes/sec)

	-- Gregory McGarry <g.mcgarry@ieee.org>