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 data-
       base 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
       metadevices; 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. Metadevices 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 configuration 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 follows: mddb number options [ slice... ] Where mddb number is the char-
       acters 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 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 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 geome-
       try, 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 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 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 specifies 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, 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 sub-
       mirrors, 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, depend-
       ing 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 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 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),
       metarecover(1M),  metarename(1M),  metareplace(1M),  metaroot(1M),  metassist(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)