emv@math.lsa.umich.edu (Edward Vielmetti) (09/01/90)
(single user mode)
# mount /usr
# cp /usr/etc/tunefs /tunefs
# umount -a
# /tunefs -m 2 /dev/rz1g
# /tunefs -m 2 /dev/rz1h
...
# mount -a -t ufs
This changes the minimum amount of free space from the default (10
percent) to a more adequate [in a disk-space-starved environment, like
ours :-(] 2% (that's the number 2 in the /tunefs commands).
The man page for tunefs(8) on SunOS 4.0.3 says
-m minfree
This value specifies the percentage of space held back
from normal users; the minimum free space threshold.
The default value used is 10%. This value can be set
to zero, however up to a factor of three in throughput
will be lost over the performance obtained at a 10%
threshold.
What does the space-performance tradeoff curve look like? If I take a
300M file system and reduce the free space allocation to 15M (5%),
will that have the same impact as trimming a 100M file system's 10M
free space to 5M ? For super performance can I go to 15% free in some
places?
Ideally I want to get enough disk space back so that people will notice
that there's more, without having them notice that it's any slower.
followups to comp.unix.admin,
--Ed
Edward Vielmetti, U of Michigan math dept <emv@math.lsa.umich.edu>