20.7. Object Naming
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## 20.7. Object Naming

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/vinum`. The configuration shown above would cause Vinum to create the following device nodes:

- The control devices `/dev/vinum/control` and `/dev/vinum/controld`, which are used by vinum(8) and the Vinum daemon respectively.

- Block and character device entries for each volume. These are the main devices used by Vinum. The block device names are the name of the volume, while the character device names follow the BSD tradition of prepending the letter r to the name. Thus the configuration above would include the block devices `/dev/vinum/myvol`, `/dev/vinum/mirror`, `/dev/vinum/striped`, `/dev/vinum/raid5` and `/dev/vinum/raid10`, and the character devices `/dev/vinum/rmyvol`, `/dev/vinum/rmirror`, `/dev/vinum/rstriped`, `/dev/vinum/rraid5` and `/dev/vinum/rraid10`. There is obviously a problem here: it is possible to have two volumes called r and rr, but there will be a conflict creating the device node `/dev/vinum/rr`: is it a character device for volume r or a block device for volume rr? Currently Vinum does not address this conflict: the first-defined volume will get the name.

- A directory `/dev/vinum/drive` with entries for each drive. These entries are in fact symbolic links to the corresponding disk nodes.

- A directory `/dev/vinum/volume` with entries for each volume. It contains subdirectories for each plex, which in turn contain subdirectories for their component subdisks.

- The directories `/dev/vinum/plex`, `/dev/vinum/sd`, and `/dev/vinum/rsd`, which contain block device nodes for each plex and block and character device nodes respectively for each subdisk.

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, vinum(8) creates the following structure in `/dev/vinum`:

brwx------ 1 root wheel 25, 0x40000001 Apr 13 16:46 Control brwx------ 1 root wheel 25, 0x40000002 Apr 13 16:46 control brwx------ 1 root wheel 25, 0x40000000 Apr 13 16:46 controld drwxr-xr-x 2 root wheel 512 Apr 13 16:46 drive drwxr-xr-x 2 root wheel 512 Apr 13 16:46 plex crwxr-xr-- 1 root wheel 91, 2 Apr 13 16:46 rs64 drwxr-xr-x 2 root wheel 512 Apr 13 16:46 rsd drwxr-xr-x 2 root wheel 512 Apr 13 16:46 rvol brwxr-xr-- 1 root wheel 25, 2 Apr 13 16:46 s64 drwxr-xr-x 2 root wheel 512 Apr 13 16:46 sd drwxr-xr-x 3 root wheel 512 Apr 13 16:46 vol /dev/vinum/drive: total 0 lrwxr-xr-x 1 root wheel 9 Apr 13 16:46 drive1 -> /dev/sd1h lrwxr-xr-x 1 root wheel 9 Apr 13 16:46 drive2 -> /dev/sd2h lrwxr-xr-x 1 root wheel 9 Apr 13 16:46 drive3 -> /dev/sd3h lrwxr-xr-x 1 root wheel 9 Apr 13 16:46 drive4 -> /dev/sd4h /dev/vinum/plex: total 0 brwxr-xr-- 1 root wheel 25, 0x10000002 Apr 13 16:46 s64.p0 /dev/vinum/rsd: 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 /dev/vinum/rvol: total 0 crwxr-xr-- 1 root wheel 91, 2 Apr 13 16:46 s64 /dev/vinum/sd: total 0 brwxr-xr-- 1 root wheel 25, 0x20000002 Apr 13 16:46 s64.p0.s0 brwxr-xr-- 1 root wheel 25, 0x20100002 Apr 13 16:46 s64.p0.s1 brwxr-xr-- 1 root wheel 25, 0x20200002 Apr 13 16:46 s64.p0.s2 brwxr-xr-- 1 root wheel 25, 0x20300002 Apr 13 16:46 s64.p0.s3 /dev/vinum/vol: total 1 brwxr-xr-- 1 root wheel 25, 2 Apr 13 16:46 s64 drwxr-xr-x 3 root wheel 512 Apr 13 16:46 s64.plex /dev/vinum/vol/s64.plex: total 1 brwxr-xr-- 1 root wheel 25, 0x10000002 Apr 13 16:46 s64.p0 drwxr-xr-x 2 root wheel 512 Apr 13 16:46 s64.p0.sd /dev/vinum/vol/s64.plex/s64.p0.sd: total 0 brwxr-xr-- 1 root wheel 25, 0x20000002 Apr 13 16:46 s64.p0.s0 brwxr-xr-- 1 root wheel 25, 0x20100002 Apr 13 16:46 s64.p0.s1 brwxr-xr-- 1 root wheel 25, 0x20200002 Apr 13 16:46 s64.p0.s2 brwxr-xr-- 1 root wheel 25, 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.

### 20.7.1. Creating File Systems

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/vinum/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/vinum/concat` newfs: /dev/vinum/concat: can't figure out file system partition

### 注意:

The following is only valid for FreeBSD versions prior to 5.0:

In order to create a file system on this volume, use the `-v` option to newfs(8):

`#` `newfs -v /dev/vinum/concat`

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