Disk space allocation

Alex Merritt merritt.alex at gmail.com
Wed Apr 15 18:45:33 UTC 2015


File systems such as ext3/4 reserve some amount of space for allocation
only by privileged users, which can be adjusted, e.g.

tune2fs -m reserved-blocks-percentage /dev/sdaN

I installed a BSD system using Virtualbox, giving it an 8GB disk, but 'df'
shows an aggregate size among all mount points to be less than the
capacity. The minfree parameter to tunefs defaults to 8% (see below) but 8%
does not account for the difference in 8189MB capacity vs sum of ca. 6G
among all file systems (shown by df). There's ca. 27% of capacity

What could I be missing here?

# fdisk
The data for partition 1 is:
sysid 165,(DragonFly/FreeBSD/NetBSD/386BSD)
    start 63, size 16773057 (8189 Meg), flag 80 (active)
beg: cyl 0/ head 1/ sector 1;
end: cyl 1023/ head 255/ sector 63

# dumpfs /dev/ad0s1a | grep minfree
minfree 8% optim time maxcontig 15 maxbpg 2048

# df -hT
Filesystem        Type     Size   Used  Avail Capacity  Mounted on
/dev/serno/--.s1a  ufs      620M   140M   431M    24%    /
devfs                   devfs    1.0K   1.0K     0B   100%    /dev
/dev/serno/--.s1d  ufs      2.2G   396K   2.0G     0%    /home
/dev/serno/--.s1e  ufs      248M    10K   228M     0%    /tmp
/dev/serno/--.s1f  ufs      2.6G   1.5G   882M    64%    /usr
/dev/serno/--.s1g  ufs      248M   213M    15M    93%    /var
procfs                  procfs   4.0K   4.0K     0B   100%    /proc


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