root@farnsworth ~ # umount /disks/disk1Also you can do it with dumpfs:
root@farnsworth ~ # umount /disks/disk2
root@farnsworth ~ # file -s /dev/wd1a
/dev/wd1a: Unix Fast File system [v1] (little-endian), last mounted on /disks/disk1, last written at Tue Jul 16 09:38:49 2013, clean flag 1, number of blocks 122096646, number of data blocks 121138363, number of cylinder groups 644, block size 32768, fragment size 4096, minimum percentage of free blocks 5, rotational delay 0ms, disk rotational speed 60rps, TIME optimization
root@farnsworth ~ # file -s /dev/wd2e
/dev/wd2e: Unix Fast File system [v1] (little-endian), last mounted on /disks/disk2, last written at Sat Jul 20 02:00:58 2013, clean flag 1, number of blocks 78142160, number of data blocks 77529094, number of cylinder groups 412, block size 32768, fragment size 4096, minimum percentage of free blocks 5, rotational delay 0ms, disk rotational speed 60rps, TIME optimization
root@farnsworth ~ #
root@farnsworth ~ # dumpfs -s /dev/wd1aDifferences between FFSv1 and FFSv2
file system: /dev/rwd1a
format FFSv1
endian little-endian
magic 11954 time Sat Jul 20 02:21:25 2013
superblock location 8192 id [ 51e514a9 69cdbabc ]
cylgrp dynamic inodes 4.4BSD sblock FFSv2 fslevel 4
nbfree 15140244 ndir 1 nifree 30334972 nffree 18
ncg 644 size 122096646 blocks 121138363
bsize 32768 shift 15 mask 0xffff8000
fsize 4096 shift 12 mask 0xfffff000
frag 8 shift 3 fsbtodb 3
bpg 23699 fpg 189592 ipg 47104
minfree 5% optim time maxcontig 2 maxbpg 8192
symlinklen 60 contigsumsize 2
maxfilesize 0x004002001005ffff
nindir 8192 inopb 256
avgfilesize 16384 avgfpdir 64
sblkno 8 cblkno 16 iblkno 24 dblkno 1496
sbsize 4096 cgsize 32768
csaddr 1496 cssize 12288
cgrotor 0 fmod 0 ronly 0 clean 0x02
wapbl version 0x1 location 2 flags 0x0
wapbl loc0 488401024 loc1 131072 loc2 512 loc3 3
flags wapbl
fsmnt /disks/disk1
volname swuid 0
From newfs man page -O option:
0 4.3BSD; This option is primarily used to build root file systems that can be understood by older boot ROMs. This generates an FFSv1 file system with level 1 format.
1 FFSv1; normal Fast File System, level 4 format. Also known as `FFS', `UFS', or `UFS1'. This is the default.
2 FFSv2; enhanced Fast File System, suited for more than 1 Terabyte capacity. This is also known as `UFS2'.
from fsck_ffs man page:
FFSv2 is suitable for large disk (1TB)
FFS1 level 0 = inode 4.2/4.3BSD static table
FFS1 level 1 = dynamic table
FFS1 level 2 = 32bit UID/GID, compact symlinks
FFS1 level 3 = free segment maps
FFS1 level 4 = FFS2 style superblock (allows WAPBL)
FFS2 level 5 = 64bit addresses, 64bit timestamps, birthtime, ext attributes
Here is example how to change default percentage of disk space held back from normal users to 1%. Default is 5% and this is too much for large disks.
root@farnsworth ~ # tunefs -m 1 /dev/wd1a
tunefs: tuning /dev/rwd1a
tunefs: minimum percentage of free space changes from 5% to 1%
tunefs: should optimize for space with minfree < 5%