fstyp reports the type of file system.
With the -v (verbose) option reports even more informations.
fstyp /dev/rdsk/c1t0d0s0
ufs
fstyp -v /dev/rdsk/c1t0d0s0
ufs
magic 11954 format dynamic time Wed Dec 23 17:26:29 2009
sblkno 16 cblkno 24 iblkno 32 dblkno 760
sbsize 2048 cgsize 8192 cgoffset 64 cgmask 0xffffffc0
ncg 427 size 20972160 blocks 20654449
bsize 8192 shift 13 mask 0xffffe000
fsize 1024 shift 10 mask 0xfffffc00
frag 8 shift 3 fsbtodb 1
minfree 1% maxbpg 2048 optim time
maxcontig 128 rotdelay 0ms rps 167
csaddr 760 cssize 7168 shift 9 mask 0xfffffe00
ntrak 48 nsect 128 spc 6144 ncyl 6827
cpg 16 bpg 6144 fpg 49152 ipg 5824
nindir 2048 inopb 64 nspf 2
nbfree 374513 ndir 37781 nifree 2110625 nffree 282680
cgrotor 357 fmod 0 ronly 0 logbno 1568
version 2
fs_reclaim FS_RECLAIM
file system state is valid, fsclean is -3
blocks available in each rotational position
cylinder number 0:
position 0: 0 8 16 24 32 40 48 56 64 72 80 88
96 104 112 120 128 136 144 152 160 168 176 184
192 200 208 216 224 232 240 248 256 264 272 280
288 296 304 312 320 328 336 344 352 360 368 376
output truncated
pfexec fstyp /dev/rdsk/c7d0s0
zfs
pfexec fstyp -v /dev/rdsk/c7d0s0
zfs
version: 14
name: 'rpool'
state: 0
txg: 6946
pool_guid: 2570515241943895053
hostid: 876213
hostname: 'workbox'
top_guid: 9425194213536263558
guid: 9425194213536263558
vdev_tree:
type: 'disk'
id: 0
guid: 9425194213536263558
path: '/dev/dsk/c7d0s0'
devid: 'id1,cmdk@AVBOX_HARDDISK=VB9cb9c5fb-995c3829/a'
phys_path: '/pci@0,0/pci-ide@1,1/ide@0/cmdk@0,0:a'
whole_disk: 0
metaslab_array: 23
metaslab_shift: 27
ashift: 9
asize: 17136615424
is_log: 0
DTL: 106
gen_clean: true
gen_guid: '9425194213536263558'
gen_version: '14'
gen_volume_label: 'rpool'