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- Correct alphabetical order of commands
- Describe subdisk attachment in more detail
- Describe new 'makedev' command
- Correct use of 'partition' and 'slice'
- Describe 'setupstate' keyword
- Include performance guidelines for striped plexes
- Correct numerical values in examples
- Add examples for disklabel(8)
- Clarify problems creating Vinum drives on inappropriate partitions
Prodded by: NAGANUMA Yasuhiro <y_naga@carat.rim.or.jp> (slices and
partitions)
This commit is contained in:
Greg Lehey
parent
c7c4322f91
commit
ef57f97a9d
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=42070
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@ -46,14 +46,10 @@ List information about volume manager state.
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.\" XXX
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Initialize a plex by writing zeroes to all its subdisks.
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.in
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.Cd l
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.Op Fl r
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.Op Fl s
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.Op Fl v
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.Op Fl V
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.Op volume | plex | subdisk
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.Cd label
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.Ar volume
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.in +1i
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List information about specified objects
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Create a volume label
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.in
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.Cd list
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.Op Fl r
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@ -64,6 +60,17 @@ List information about specified objects
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.in +1i
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List information about specified objects
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.in
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.Cd l
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.Op Fl r
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.Op Fl s
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.Op Fl v
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.Op Fl V
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.Op volume | plex | subdisk
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.in +1i
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List information about specified objects (alternative to
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.Cd list
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command)
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.in
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.Cd ld
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.Op Fl r
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.Op Fl s
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@ -100,10 +107,9 @@ List information about plexes
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.in +1i
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List information about volumes
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.in
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.Cd label
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.Ar volume
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.Cd makedev
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.in +1i
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Create a volume label
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Remake the device nodes in /dev/vinum.
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.in
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.Cd read
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.Ar disk-partition
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@ -256,6 +262,25 @@ renames the object (and in the case of a plex, any subordinate subdisks) to fit
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in with the default
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.Nm
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naming convention.
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.Pp
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A number of considerations apply to attaching subdisks:
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.Bl -bullet
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.It
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Subdisks can normally only be attached to concatenated plexes.
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.It
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If a striped or RAID-5 plex is missing a subdisk (for example after drive
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failure), it may be replaced by a subdisk of the same size only. No other
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attachment of subdisks is currently allowed.
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.It
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For concatenated plexes, the
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.Ar offset
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parameter specifies the offset in blocks from the beginning of the plex. For
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striped and RAID-5 plexes, it specifies the offset of the first block of the
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subdisk: in other words, the offset is the numerical position of the subdisk
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multiplied by the stripe size. For example, in a plex of block size 256k, the
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first subdisk will have offset 0, the second offset 256k, the third 512k, etc.
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This calculation ignores parity blocks in RAID-5 plexes.
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.El
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.It Nm create Ar description-file
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.sp
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.Nm
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@ -291,6 +316,12 @@ option is specified. If the object is named after the object above it (for
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example, subdisk vol1.p7.s0 attached to plex vol1.p7), the name will be changed
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by prepending the text ``ex-'' (for example, ex-vol1.p7.s0). If necessary, the
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name will be truncated in the process.
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.Pp
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.Nm detach
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does not reduce the number of subdisks in a striped or RAID-5 plex. Instead,
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the subdisk is marked absent, and can later be replaced with the
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.Nm attach
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command.
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.It Nm info
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.Pp
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.Nm
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@ -314,6 +345,27 @@ initializes all subdisks of a plex in parallel. Since this operation can take a
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long time, it is performed in the background.
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.Nm
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prints a console message when the initialization is complete.
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.It Nm label
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.Ar volume
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.Pp
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The
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.Nm label
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command writes a
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.Ar ufs
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style volume label on a volume. It is a simple alternative to an appropriate
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call to
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.Ar disklabel .
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This is needed because some
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.Ar ufs
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commands still read the disk to find the label instead of using the correct
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.Ar ioctl
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call to access it.
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.Nm
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maintains a volume label separately from the volume data, so this command is not
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needed for
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.Ar newfs .
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This command is deprecated.
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.Pp
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.It Nm list
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.Op Fl r
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.Op Fl V
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@ -383,26 +435,13 @@ to output device statistics, the
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(verbose) option causes some additional information to be output, and the
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.Op Fl V
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causes considerable additional information to be output.
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.It Nm label
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.Ar volume
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.Pp
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.It Nm makedev
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.br
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The
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.Nm label
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command writes a
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.Ar ufs
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style volume label on a volume. It is a simple alternative to an appropriate
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call to
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.Ar disklabel .
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This is needed because some
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.Ar ufs
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commands still read the disk to find the label instead of using the correct
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.Ar ioctl
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call to access it.
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.Nm
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maintains a volume label separately from the volume data, so this command is not
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needed for
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.Ar newfs .
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This command is deprecated.
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.Nm makedev
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command removes the directory /dev/vinum and recreates it with device nodes
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which reflect the current configuration. This command is not intended for
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general use, and is provided for emergency use only.
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.Pp
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.It Nm read
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.Ar disk-partition
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@ -413,8 +452,8 @@ command reads a previously created
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.Nm
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configuration from the specified disk partition.
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.Nm
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maintains an up-to-date copy of all configuration information on each of the
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disk slices. You can specify any of the partitions in a configuration as the
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maintains an up-to-date copy of all configuration information on each disk
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partition. You can specify any of the partitions in a configuration as the
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parameter to this command.
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.It Nm rename
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.Op Fl r
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@ -532,12 +571,10 @@ subsystem or one of its components. To start a plex in a multi-plex volume, the
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data must be copied from another plex in the volume. This frequently takes a
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long time and is done in the background.
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.ig
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XXX
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When invoked without arguments, it checks
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all disks connected to the system for BSD partitions (type 165) and scans the
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slices for a
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XXX When invoked without arguments, it checks all disks connected to the system
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for BSD partitions (type 165) and scans the partitions for a
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.Nm
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slice, which it calls a \fIdrive\fR\|. The
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partition, which it calls a \fIdrive\fR\|. The
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.Nm
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drive contains a header with all information about the data stored on the drive,
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including the names of the other drives which are required in order to represent
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@ -644,7 +681,9 @@ command to first bring them to a consistent state. In the case of striped and
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concatenated plexes, however, it does not normally cause problems to leave them
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inconsistent: when using a volume for a file system or a swap partition, the
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previous contents of the disks are not of interest, so they may be ignored.
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If you want to take this risk, use this keyword.
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If you want to take this risk, use this keyword. It will only apply to the
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plexes defined immediately after the volume in the configuration file. If you
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add plexes to a volume at a later time, you must integrate them.
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.Pp
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Note that you \fImust\fP\| use the
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.Nm init
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@ -700,6 +739,12 @@ it specifies the size of a group. A group is a portion of a plex which
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stores the parity bits all in the same subdisk. It must be a factor of the plex size (in
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other words, the result of dividing the plex size by the stripe size must be an
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integer), and it must be a multiple of a disk sector (512 bytes).
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.sp
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For optimum performance, stripes should be at least 128 kB in size: anything
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smaller will result in a significant increase in I/O activity due to mapping of
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individual requests over multiple disks. The increase in concurrency due to
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this mapping will not make up for the increase in latency. A good guideline for
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stripe size is between 256 kB and 512 kB.
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T}
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.Pp
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#T{
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@ -849,14 +894,14 @@ volume concat
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sd length 100m drive drive2
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sd length 50m drive drive4
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plex org concat
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sd length 100m drive drive4
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sd length 150m drive drive4
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# A volume with one striped plex and one concatenated plex
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volume strcon
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plex org striped 32b
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sd length 100m drive drive2
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sd length 100m drive drive4
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plex org concat
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sd length 100m drive drive2
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sd length 150m drive drive2
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sd length 50m drive drive4
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# a volume with a RAID-5 and a striped plex
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# note that the RAID-5 volume is longer by
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@ -880,13 +925,56 @@ in order to avoid overwriting file systems. In later versions of
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.Nm
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this requirement will change to type
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.Ar vinum .
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Use
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.Nm disklabel
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.Ar -e
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to edit a partition type definition. The following display shows a typical
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partition layout as shown by
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.Nm disklabel:
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.nf
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8 partitions:
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# size offset fstype [fsize bsize bps/cpg]
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a: 81920 344064 4.2BSD 0 0 0 # (Cyl. 240*- 297*)
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b: 262144 81920 swap # (Cyl. 57*- 240*)
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c: 4226725 0 unused 0 0 # (Cyl. 0 - 2955*)
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e: 81920 0 4.2BSD 0 0 0 # (Cyl. 0 - 57*)
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f: 1900000 425984 4.2BSD 0 0 0 # (Cyl. 297*- 1626*)
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g: 1900741 2325984 unused 0 0 0 # (Cyl. 1626*- 2955*)
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.fi
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.sp
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In this example, partition
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.Nm g
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may be used as a
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.Nm
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partition. Partitions
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.Nm a ,
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.Nm e
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and
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.Nm f
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may be used as
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.Nm UFS
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file systems or
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.Nm ccd
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partitions. Partition
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.Nm b
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is a swap partition, and partition
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.Nm c
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represents the whole disk and should not be used for any other purpose.
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.Pp
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.Nm
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uses the first 265 sectors on each partition for configuration information, so
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the maximum size of a subdisk is 265 sectors smaller than the drive.
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.Sh GOTCHAS
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.Nm
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will not create a device on UFS partitions. Instead, it will return an error
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message ``wrong partition type''. The partition type must currently be
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``unused''. See above for more details.
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.Sh BUGS
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.Nm
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is currently in beta test. Many bugs can be expected. The configuration
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mechanism is not yet fully functional.
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mechanism is not yet fully functional. If you have difficulties, please look at
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http://www.lemis.com/vinum_beta.html and
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http://www.lemis.com/vinum_debugging.html before reporting problems.
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.Sh FILES
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.Ar /dev/vinum
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- directory with device nodes for
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@ -908,6 +996,7 @@ plexes.
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subdisks.
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.Sh SEE ALSO
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.Xr vinum 4
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.Xr disklabel 8
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.Sh AUTHOR
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Greg Lehey
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.Pa <grog@lemis.com> .
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