As described above, Vinum assigns default names to plexes and subdisks, although they
may be overridden. Overriding the default names is not recommended: experience with the
VERITAS volume manager, which allows arbitrary naming of objects, has shown that this
flexibility does not bring a significant advantage, and it can cause confusion.
Names may contain any non-blank character, but it is recommended to restrict them to
letters, digits and the underscore characters. The names of volumes, plexes and subdisks
may be up to 64 characters long, and the names of drives may be up to 32 characters
long.
Vinum objects are assigned device nodes in the hierarchy /dev/gvinum. The configuration shown above would cause Vinum to
create the following device nodes:
-
Note: This only applies to the historic Vinum implemenation.
The control devices /dev/vinum/control and /dev/vinum/controld, which are used by gvinum(8) and the
Vinum daemon respectively.
-
Device entries for each volume. These are the main devices used by Vinum. Thus the
configuration above would include the devices /dev/gvinum/myvol, /dev/gvinum/mirror,
/dev/gvinum/striped, /dev/gvinum/raid5 and /dev/gvinum/raid10.
-
Note: This only applies to the historic Vinum implemenation.
A directory /dev/vinum/drive with entries for each drive.
These entries are in fact symbolic links to the corresponding disk nodes.
-
All volumes get direct entries under /dev/gvinum/.
-
The directories /dev/gvinum/plex, and /dev/gvinum/sd, which contain device nodes for each plex and for
each subdisk, respectively.
For example, consider the following configuration file:
drive drive1 device /dev/sd1h
drive drive2 device /dev/sd2h
drive drive3 device /dev/sd3h
drive drive4 device /dev/sd4h
volume s64 setupstate
plex org striped 64k
sd length 100m drive drive1
sd length 100m drive drive2
sd length 100m drive drive3
sd length 100m drive drive4
After processing this file, gvinum(8) creates the
following structure in /dev/gvinum:
drwxr-xr-x 2 root wheel 512 Apr 13 16:46 plex
crwxr-xr-- 1 root wheel 91, 2 Apr 13 16:46 s64
drwxr-xr-x 2 root wheel 512 Apr 13 16:46 sd
/dev/vinum/plex:
total 0
crwxr-xr-- 1 root wheel 25, 0x10000002 Apr 13 16:46 s64.p0
/dev/vinum/sd:
total 0
crwxr-xr-- 1 root wheel 91, 0x20000002 Apr 13 16:46 s64.p0.s0
crwxr-xr-- 1 root wheel 91, 0x20100002 Apr 13 16:46 s64.p0.s1
crwxr-xr-- 1 root wheel 91, 0x20200002 Apr 13 16:46 s64.p0.s2
crwxr-xr-- 1 root wheel 91, 0x20300002 Apr 13 16:46 s64.p0.s3
Although it is recommended that plexes and subdisks should not be allocated specific
names, Vinum drives must be named. This makes it possible to move a drive to a different
location and still recognize it automatically. Drive names may be up to 32 characters
long.
Volumes appear to the system to be identical to disks, with one exception. Unlike
UNIX® drives, Vinum does not partition volumes, which
thus do not contain a partition table. This has required modification to some disk
utilities, notably newfs(8), which
previously tried to interpret the last letter of a Vinum volume name as a partition
identifier. For example, a disk drive may have a name like /dev/ad0a or /dev/da2h. These names
represent the first partition (a) on the first (0) IDE disk
(ad) and the eighth partition (h)
on the third (2) SCSI disk (da) respectively. By contrast, a
Vinum volume might be called /dev/gvinum/concat, a name which
has no relationship with a partition name.
Normally, newfs(8) interprets
the name of the disk and complains if it cannot understand it. For example:
# newfs /dev/gvinum/concat
newfs: /dev/gvinum/concat: can't figure out file system partition
In order to create a file system on this volume, use newfs(8):
# newfs /dev/gvinum/concat
Note: On FreeBSD versions prior to 5.0 newfs(8) requires an
additional -v flag and the old device naming scheme:
# newfs -v /dev/vinum/concat
