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File Formats                                            md.tab(4)



NAME
     md.tab, md.cf - Solaris Volume Manager utility files

SYNOPSIS
     /etc/lvm/md.tab
     /etc/lvm/md.cf

DESCRIPTION
     The file /etc/lvm/md.tab can be  used  by  metainit(1M)  and
     metadb(1M)  to  configure  metadevices, hot spare pools, and
     metadevice state database replicas  in  a  batch-like  mode.
     Solaris Volume Manager does not store configuration informa-
     tion in the /etc/lvm/md.tab file. You can  use  metainit  -p
     /etc/lvm/md.tab  to create this file.  Edit it by hand using
     the instructions in md.tab.4. Similarly, if  no  hot  spares
     are in use, the cp md.cf md.tab command generates an accept-
     able version of the md.tab file, with  the  editing  caveats
     previously mentioned.

     When using the md.tab file, each metadevice, hot spare pool,
     or  state  database  replica  in the file must have a unique
     entry. Entries can include the following: simple metadevices
     (stripes,  concatenations,  and  concatenations of stripes);
     mirrors, trans metadevices, soft partitions, and RAID5 meta-
     devices;  hot  spare  pools;  and  state  database replicas.
     Because md.tab contains only entries that you enter  in  it,
     do  not  rely  on  the file for the current configuration of
     metadevices, hot spare pools, and replicas on the system  at
     any given time.

     Tabs, spaces, comments (by using a pound sign, #), and  con-
     tinuation  of  lines  (by  using  a  backslash-newline), are
     allowed.

     Typically, you set up metadevices according  to  information
     specified on the command line by using the metainit command.
     Likewise, you set up state database replicas with the metadb
     command.

     An alternative to the command line  is  to  use  the  md.tab
     file.  Metadevices and state database replicas can be speci-
     fied in the md.tab file in any order, and then activated  in
     a batch-like mode with the metainit and metadb commands.

     If you edit the md.tab file, you specify one complete confi-
     guration  entry  per line. Metadevices are defined using the
     same syntax as required by the metainit  command.  You  then
     run  the  metainit  command  with  either  the -a option, to
     activate all metadevices in the md.tab  file,  or  with  the
     metadevice  name  corresponding  to a specific configuration
     entry.




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File Formats                                            md.tab(4)



     metainit does not maintain the state  of  the  volumes  that
     would  have  been created when metainit is run with both the
     -a and -n flags. If a device d0 is created in the first line
     of  the  md.tab file, and a later line in md.tab assumes the
     existence of d0, the later line will fail when metainit  -an
     runs (even if it would succeed with metainit -a).

     State database replicas are defined in  the  /etc/lvm/md.tab
     file as follows: mddb number options [ slice... ] Where mddb
     number is the characters mddb followed by a number of two or
     more  digits  that  identifies  the  state database replica.
     slice   is   a   physical   slice.   For   example:   mddb05
     /dev/dsk/c0t1d0s2.  The  file  /etc/lvm/md.cf is a backup of
     the configuration used for disaster recovery.  Whenever  the
     Volume  Manager  configuration  is  changed,  this  file  is
     automatically updated (except when hot sparing occurs).  You
     should not directly edit this file.

  Limitations
     Recursive mirroring is not allowed; that is, a mirror cannot
     appear in the definition of another mirror.

     Recursive logging is not allowed; that is, a trans  metadev-
     ice cannot appear in the definition of another metadevice.

     Stripes and RAID5 metadevices must contains slices  or  soft
     partitions only.

     Mirroring of RAID5 metadevices is not allowed.

     Soft partitions can be built directly on slices  or  can  be
     the  top  level  (accessible  by applications directly), but
     cannot be in the middle, with other  metadevices  above  and
     below them.

EXAMPLES
     Example 1: Concatenation

     All drives in the following examples have the same  size  of
     525 Mbytes.

     This example shows a metadevice, /dev/md/dsk/d7,  consisting
     of a concatenation of four disks.

     #
     # (concatenation of four disks)
     #
     d7 4 1 c0t1d0s0 1 c0t2d0s0 1 c0t3d0s0 1 c0t4d0s0

     The number 4 indicates there are four individual stripes  in
     the  concatenation.  Each stripe is made of one slice, hence
     the number 1 appears in front of each slice. Note  that  the



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File Formats                                            md.tab(4)



     first  disk  sector  in  all of the above devices contains a
     disk   label.   To   preserve   the   labels   on    devices
     /dev/dsk/c0t2d0s0, /dev/dsk/c0t3d0s0, and /dev/dsk/c0t4d0s0,
     the metadisk driver must skip at least the first  sector  of
     those  disks  when mapping accesses across the concatenation
     boundaries. Since  skipping  only  the  first  sector  would
     create an irregular disk geometry, the entire first cylinder
     of these disks will be skipped.  This  allows  higher  level
     file   system   software   to   optimize  block  allocations
     correctly.

     Example 2: Stripe

     This example shows a metadevice, /dev/md/dsk/d15, consisting
     of two slices.

     #
     # (stripe consisting of two disks)
     #
     d15 1 2 c0t1d0s2 c0t2d0s2 -i 32k

     The number 1 indicates that one  stripe  is  being  created.
     Because  the stripe is made of two slices, the number 2 fol-
     lows next. The optional -i followed  by  32k  specifies  the
     interlace size will be 32 Kbytes. If the interlace size were
     not specified, the stripe would use the default value of  16
     Kbytes.

     Example 3: Concatenation of Stripes

     This example shows a metadevice, /dev/md/dsk/d75, consisting
     of a concatenation of two stripes of three disks.

     #
     # (concatenation of two stripes, each consisting of three disks)
     #
     d75 2 3 c0t1d0s2 c0t2d0s2 c0t3d0s2 -i 16k \
           3 c1t1d0s2 c1t2d0s2 c1t3d0s2 -i 32k

     On the first line, the -i followed by 16k specifies that the
     stripe's  interlace size is 16 Kbytes. The second set speci-
     fies the stripe interlace size will be  32  Kbytes.  If  the
     second  set  did  not  specify  32 Kbytes, the set would use
     default interlace value of 16 Kbytes. The blocks of each set
     of three disks are interlaced across three disks.

     Example 4: Mirroring

     This example shows a three-way mirror, /dev/md/dsk/d50, con-
     sisting  of  three  submirrors. This mirror does not contain
     any existing data.




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File Formats                                            md.tab(4)



     #
     # (mirror)
     #
     d50 -m d51
     d51 1 1 c0t1d0s2
     d52 1 1 c0t2d0s2
     d53 1 1 c0t3d0s2

     In this example, a one-way mirror is first defined using the
     -m option. The one-way mirror consists of submirror d51. The
     other two submirrors, d52 and d53, are attached later  using
     the  metattach  command.  The default read and write options
     in this example are a round-robin read algorithm and  paral-
     lel  writes  to  all  submirrors. The order in which mirrors
     appear in the /etc/lvm/md.tab file is unimportant.

     Example 5: Logging (trans)

     This example shows a trans metadevice, /dev/md/dsk/d1,  with
     mirrors  for the master and logging devices. This trans does
     not contain any existing data.

     #
     # (trans)
     #
     d1 -t d10 d20
     d10 -m d11
     d11 1 1 c0t1d0s2
     d12 1 1 c0t2d0s2
     d20 -m d21
     d21 1 1 c1t1d0s2
     d22 1 1 c1t2d0s2

     In this example, the two mirrors, d10 and d20,  are  defined
     using the -m option. d10 is defined as the master device and
     d20 is defined as the logging device for the trans,  d1,  by
     using  the  -t  option.  The order in which mirrors or trans
     appear in the /etc/lvm/md.tab file is unimportant. The  sub-
     mirrors  d12 and d22 are attached later (using the metattach
     command) to the d10 and d20 mirrors.

     Example 6: RAID5

     This example shows a RAID5 metadevice,  d80,  consisting  of
     three slices:

     #
     # (RAID devices)
     #
     d80 -r c0t1d0s1 c1t0d0s1 c2t0d0s1 -i 20k





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File Formats                                            md.tab(4)



     In this example, a RAID5 metadevice is defined using the  -r
     option  with  an  interlace  size of 20 Kbytes. The data and
     parity segments will be striped across the slices, c0t1d0s1,
     c1t0d0s1, and c2t0d0s1.

     Example 7: Soft Partition

     This example shows a soft partition, d85, that reformats  an
     entire  9  GB  disk. Slice 0 occupies all of the disk except
     for the few Mbytes taken by slice 7, which is space reserved
     for  a  state database replica. Slice 7 will be a minimum of
     4Mbytes,  but  could  be  larger,  depending  on  the   disk
     geometry. d85 sits on c3t4d0s0.

     Drives are repartitioned when they are added  to  a  diskset
     only  if Slice 7 is not set up correctly. A small portion of
     each drive is reserved in Slice 7 for use by Volume Manager.
     The  remainder  of  the  space  on each drive is placed into
     Slice 0. Any existing data on the disks is lost after repar-
     titioning.   After  adding  a  drive  to  a diskset, you can
     repartition the drive as necessary. However, Slice 7  should
     not  be  moved, removed, or overlapped with any other parti-
     tion.

     Manually specifying the offsets and extents of  soft  parti-
     tions  is  not  recommended. This example is included for to
     provide a better understanding of the file if it is automat-
     ically generated and for completeness.

     #
     # (Soft Partitions)
     d85 -p -e c3t4d0 9g

     In this example, creating the soft  partition  and  required
     space  for  the  state database replica occupies all 9 GB of
     disk c3t4d0.

     Example 8: Soft Partition

     This example shows the command used to re-create a soft par-
     tition  with  two  extents, the first one starting at offset
     20483 and extending for 20480 blocks and the  second  extent
     starting at 135398 and extending for 20480 blocks:

     #
     # (Soft Partitions)
     #
     d1 -p c0t3d0s0 -o 20483 -b 20480 -o 135398 -b 20480

     Example 9: Hot Spare





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File Formats                                            md.tab(4)



     This example shows a three-way mirror, /dev/md/dsk/d10, con-
     sisting of three submirrors and three hot spare pools.

     #
     # (mirror and hot spare)
     #
     d10 -m d20
     d20 1 1 c1t0d0s2 -h hsp001
     d30 1 1 c2t0d0s2 -h hsp002
     d40 1 1 c3t0d0s2 -h hsp003
     hsp001 c2t2d0s2 c3t2d0s2 c1t2d0s2
     hsp002 c3t2d0s2 c1t2d0s2 c2t2d0s2
     hsp003 c1t2d0s2 c2t2d0s2 c3t2d0s2

     In this example, a one-way mirror is first defined using the
     -m  option.  The  submirrors  are  attached  later using the
     metattach(1M) command.  The hot spare pools to be  used  are
     tied  to the submirrors with the -h option. In this example,
     there are three disks used as hot spares, defined  in  three
     separate  hot spare pools. The hot spare pools are given the
     names hsp001, hsp002, and hsp003. Setting up three hot spare
     pools  rather  than  assigning  just one hot spare with each
     component helps to maximize the use of hardware. This confi-
     guration enables the user to specify that the most desirable
     hot spare be selected first, and  improves  availability  by
     having  more  hot spares available. At the end of the entry,
     the hot spares to be used are defined. Note that, when using
     the  md.tab  file, to associate hot spares with metadevices,
     the hot spare spool does not have  to  exist  prior  to  the
     association. Volume Manager takes care of the order in which
     metadevices and hot spares are created when using the md.tab
     file.

     Example 10: State Database Replicas

     This example shows how to set up an initial  state  database
     and three replicas on a server that has three disks.

     #
     # (state database and replicas)
     #
     mddb01 -c 3 c0t1d0s0 c0t2d0s0 c0t3d0s0

     In this example, three state database replicas are stored on
     each  of  the  three slices. Once the above entry is made in
     the /etc/lvm/md.tab file, the metadb  command  must  be  run
     with  both  the  -a  and -f options. For example, typing the
     following command creates one  state  database  replicas  on
     three slices:

     # metadb -a -f mddb01




SunOS 5.9           Last change: 18 Feb 2003                    6






File Formats                                            md.tab(4)



FILES
     /etc/lvm/md.tab


     /etc/lvm/md.cf


SEE ALSO
     metaclear(1M),   metadb(1M),   metadetach(1M),   metahs(1M),
     metainit(1M),        metaoffline(1M),        metaonline(1M),
     metaparam(1M),       metarecover(1M),       metareplace(1M),
     metaroot(1M),   metastat(1M),  metasync(1M),  metattach(1M),
     mddb.cf(4)

     Solaris Volume Manager Administration Guide








































SunOS 5.9           Last change: 18 Feb 2003                    7