unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (SunOS-5.10)
Page:
Section:
Apropos / Subsearch:
optional field

md.tab(4)                        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 information in the /etc/lvm/md.tab file. You can use:

       metastat -p > /etc/lvm/md.tab

       to create this file. Edit it by hand  using  the  instructions  in  the
       md.tab.4  file.  Similarly,  if  no hot spares are in use, the cp md.cf
       md.tab command generates an acceptable 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, soft partitions, and RAID5 metade-
       vices;  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 continuation  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. Metade-
       vices and state database replicas can be specified 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  configuration
       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  configu-
       ration entry.

       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 fol-
       lows: mddb number options [ slice... ] Where mddb number is the charac-
       ters  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.

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  con-
       catenation 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 con-
       catenation.  Each stripe is made of  one  slice,  hence  the  number  1
       appears  in front of each slice. Note that the 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 skip-
       ping 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  cor-
       rectly.

       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 follows 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  con-
       catenation 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 specifies the stripe inter-
       lace  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, consisting of
       three submirrors. This mirror does not contain any existing data.

       #
       # (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 submir-
       rors, 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 parallel writes to all submirrors.  The  order  in  which
       mirrors appear in the /etc/lvm/md.tab file is unimportant.

       Example 5: RAID5

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

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


       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 6: 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  repartitioning.   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 partition.

       Manually  specifying  the offsets and extents of soft partitions is not
       recommended. This example is included for to provide  a  better  under-
       standing of the file if it is automatically generated and for complete-
       ness.

       #
       # (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 7: Soft Partition

       This  example shows the command used to re-create a soft partition 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 8: Hot Spare

       This example shows a three-way mirror, /dev/md/dsk/d10,  consisting  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 configuration  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 9: 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


FILES
         o  /etc/lvm/md.tab

         o  /etc/lvm/md.cf


SEE ALSO
       mdmonitord(1M), metaclear(1M), metadb(1M), metadetach(1M),  metahs(1M),
       metainit(1M),  metaoffline(1M),  metaonline(1M), metaparam(1M), metare-
       cover(1M),  metarename(1M),   metareplace(1M),   metaroot(1M),   metas-
       sist(1M),   metaset(1M),   metastat(1M),  metasync(1M),  metattach(1M),
       md.cf(4), mddb.cf(4), attributes(5), md(7D)

       Solaris Volume Manager Administration Guide

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

       Recursive logging is not allowed.

       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.

NOTES
       Trans metadevices have been replaced by  UFS  logging.  Existing  trans
       devices  are not logging--they pass data directly through to the under-
       lying device. See mount_ufs(1M) for more information about UFS logging.



SunOS 5.10                        15 Dec 2004                        md.tab(4)