'\" te
.\" Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH METADB 1M "Mar 26, 2006"
.SH NAME
metadb \- create and delete replicas of the metadevice state database
.SH SYNOPSIS
.LP
.nf
\fB/sbin/metadb\fR \fB-h\fR
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR]
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR] \fB-a\fR [\fB-f\fR] [\fB-k\fR \fIsystem-file\fR] mddb\fInn\fR
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR] \fB-a\fR [\fB-f\fR] [\fB-k\fR \fIsystem-file\fR]
     [\fB-c\fR \fInumber\fR] [\fB-l\fR \fIlength\fR] \fIslice...\fR
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR] \fB-d\fR [\fB-f\fR] [\fB-k\fR \fIsystem-file\fR] mddb\fInn\fR
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR] \fB-d\fR [\fB-f\fR] [\fB-k\fR \fIsystem-file\fR] \fIslice...\fR
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR] \fB-i\fR
.fi

.LP
.nf
\fB/sbin/metadb\fR [\fB-s\fR \fIsetname\fR] \fB-p\fR [\fB-k\fR \fIsystem-file\fR]
     [\fImddb.cf-file\fR]
.fi

.SH DESCRIPTION
.sp
.LP
The \fBmetadb\fR command creates and deletes replicas of the metadevice state
database. State database replicas can be created on dedicated slices, or on
slices that will later become part of a simple metadevice (concatenation or
stripe) or RAID5 metadevice. Do not place state database replicas on
fabric-attached storage, SANs, or other storage that is not directly attached
to the system and available at the same point in the boot process as
traditional SCSI or IDE drives. See \fBNOTES\fR.
.sp
.LP
The metadevice state database contains the configuration of all metadevices and
hot spare pools in the system. Additionally, the metadevice state database
keeps track of the current state of metadevices and hot spare pools, and their
components. Solaris Volume Manager automatically updates the metadevice state
database when a configuration or state change occurs. A submirror failure is an
example of a state change. Creating a new metadevice is an example of a
configuration change.
.sp
.LP
The metadevice state database is actually a collection of multiple, replicated
database copies. Each copy, referred to as a replica, is subject to strict
consistency checking to ensure correctness.
.sp
.LP
Replicated databases have an inherent problem in determining which database has
valid and correct data. To solve this problem, Volume Manager uses a
\fImajority consensus algorithm\fR. This algorithm requires that a majority of
the database replicas be available before any of them are declared valid. This
algorithm strongly encourages the presence of at least three initial replicas,
which you create. A consensus can then be reached as long as at least two of
the three replicas are available. If there is only one replica and the system
crashes, it is possible that all metadevice configuration data can be lost.
.sp
.LP
The majority consensus algorithm is conservative in the sense that it will fail
if a majority consensus cannot be reached, even if one replica actually does
contain the most up-to-date data. This approach guarantees that stale data will
not be accidentally used, regardless of the failure scenario. The majority
consensus algorithm accounts for the following: the system will stay running
with exactly half or more replicas; the system will panic when less than half
the replicas are available; the system will not reboot without one more than
half the total replicas.
.sp
.LP
When used with no options, the \fBmetadb\fR command gives a short form of the
status of the metadevice state database. Use \fBmetadb\fR \fB-i\fR for an
explanation of the flags field in the output.
.sp
.LP
The initial state database is created using the \fBmetadb\fR command with both
the \fB-a\fR and \fB-f\fR options, followed by the slice where the replica is
to reside. The \fB-a\fR option specifies that a replica (in this case, the
initial) state database should be created. The \fB-f\fR option forces the
creation to occur, even though a state database does not exist. (The \fB-a\fR
and \fB-f\fR options should be used together only when no state databases
exist.)
.sp
.LP
Additional replicas beyond those initially created can be added to the system.
They contain the same information as the existing replicas, and help to prevent
the loss of the configuration information. Loss of the configuration makes
operation of the metadevices impossible. To create additional replicas, use the
\fBmetadb\fR \fB-a\fR command, followed by the name of the new slice(s) where
the replicas will reside. All replicas that are located on the same slice must
be created at the same time.
.sp
.LP
To delete all replicas that are located on the same slice, the \fBmetadb\fR
\fB-d\fR command is used, followed by the slice name.
.sp
.LP
When used with the \fB-i\fR option, \fBmetadb\fR displays the status of the
metadevice state databases. The status can change if a hardware failure occurs
or when state databases have been added or deleted.
.sp
.LP
To fix a replica in an error state, delete the replica and add it back again.
.sp
.LP
The metadevice state database (\fBmddb\fR) also contains a list of the replica
locations for this set (local or shared diskset).
.sp
.LP
The local set \fBmddb\fR can also contain host and drive information for each
of the shared disksets of which this node is a member. Other than the diskset
host and drive information stored in the local set \fBmddb\fR, the local and
shared diskset \fBmddb\fRs are functionality identical.
.sp
.LP
The \fBmddb\fRs are written to during the resync of a mirror or during a
component failure or configuration change. A configuration change or failure
can also occur on a single replica (removal of a \fBmddb\fR or a failed disk)
and this causes the other replicas to be updated with this failure information.
.SH OPTIONS
.sp
.LP
Root privileges are required for all of the following options except \fB-h\fR
and \fB-i\fR.
.sp
.LP
The following options can be used with the \fBmetadb\fR command. Not all the
options are compatible on the same command line. Refer to the \fBSYNOPSIS\fR to
see the supported use of the options.
.sp
.ne 2
.na
\fB\fB-a\fR\fR
.ad
.RS 18n
Attach a new database device. The \fB/kernel/drv/md.conf\fR file is
automatically updated with the new information and the \fB/etc/lvm/mddb.cf\fR
file is updated as well. An alternate way to create replicas is by defining
them in the \fB/etc/lvm/md.tab\fR file and specifying the assigned name at the
command line in the form, \fBmddb\fInn\fR\fR, where \fInn\fR is a two-digit
number given to the replica definitions. Refer to the \fBmd.tab\fR(4) man page
for instructions on setting up replicas in that file.
.RE

.sp
.ne 2
.na
\fB\fB-c\fR \fInumber\fR\fR
.ad
.RS 18n
Specifies the number of replicas to be placed on each device. The default
number of replicas is 1.
.RE

.sp
.ne 2
.na
\fB\fB-d\fR\fR
.ad
.RS 18n
Deletes all replicas that are located on the specified \fIslice\fR. The
\fB/kernel/drv/md.conf\fR file is automatically updated with the new
information and the \fB/etc/lvm/mddb.cf\fR file is updated as well.
.RE

.sp
.ne 2
.na
\fB\fB-f\fR\fR
.ad
.RS 18n
The \fB-f\fR option is used to create the initial state database. It is also
used to force the deletion of replicas below the minimum of one. (The \fB-a\fR
and \fB-f\fR options should be used together only when no state databases
exist.)
.RE

.sp
.ne 2
.na
\fB\fB-h\fR\fR
.ad
.RS 18n
Displays a usage message.
.RE

.sp
.ne 2
.na
\fB\fB-i\fR\fR
.ad
.RS 18n
Inquire about the status of the replicas. The output of the \fB-i\fR option
includes characters in front of the device name that represent the status of
the state database. Explanations of the characters are displayed following the
replica status and are as follows:
.sp
.ne 2
.na
\fB\fBd\fR\fR
.ad
.RS 5n
replica does not have an associated device ID.
.RE

.sp
.ne 2
.na
\fB\fBo\fR\fR
.ad
.RS 5n
replica active prior to last \fBmddb\fR configuration change
.RE

.sp
.ne 2
.na
\fB\fBu\fR\fR
.ad
.RS 5n
replica is up to date
.RE

.sp
.ne 2
.na
\fB\fBl\fR\fR
.ad
.RS 5n
locator for this replica was read successfully
.RE

.sp
.ne 2
.na
\fB\fBc\fR\fR
.ad
.RS 5n
replica's location was in \fB/etc/lvm/mddb.cf\fR
.RE

.sp
.ne 2
.na
\fB\fBp\fR\fR
.ad
.RS 5n
replica's location was patched in kernel
.RE

.sp
.ne 2
.na
\fB\fBm\fR\fR
.ad
.RS 5n
replica is master, this is replica selected as input
.RE

.sp
.ne 2
.na
\fB\fBr\fR\fR
.ad
.RS 5n
replica does not have device relocation information
.RE

.sp
.ne 2
.na
\fB\fBt\fR\fR
.ad
.RS 5n
tagged data is associated with the replica
.RE

.sp
.ne 2
.na
\fB\fBW\fR\fR
.ad
.RS 5n
replica has device write errors
.RE

.sp
.ne 2
.na
\fB\fBa\fR\fR
.ad
.RS 5n
replica is active, commits are occurring to this
.RE

.sp
.ne 2
.na
\fB\fBM\fR\fR
.ad
.RS 5n
replica had problem with master blocks
.RE

.sp
.ne 2
.na
\fB\fBD\fR\fR
.ad
.RS 5n
replica had problem with data blocks
.RE

.sp
.ne 2
.na
\fB\fBF\fR\fR
.ad
.RS 5n
replica had format problems
.RE

.sp
.ne 2
.na
\fB\fBS\fR\fR
.ad
.RS 5n
replica is too small to hold current database
.RE

.sp
.ne 2
.na
\fB\fBR\fR\fR
.ad
.RS 5n
replica had device read errors
.RE

.sp
.ne 2
.na
\fB\fBB\fR\fR
.ad
.RS 5n
tagged data associated with the replica is not valid
.RE

.RE

.sp
.ne 2
.na
\fB\fB-k\fR \fIsystem-file\fR\fR
.ad
.RS 18n
Specifies the name of the kernel file where the replica information should be
written. The default \fIsystem-file\fR is \fB/kernel/drv/md.conf\fR. This
option is for use with the local diskset only.
.RE

.sp
.ne 2
.na
\fB\fB-l\fR \fIlength\fR\fR
.ad
.RS 18n
Specifies the size of each replica. The default \fIlength\fR is 8192 blocks,
which should be appropriate for most configurations. "Replica" sizes of less
than 128 blocks are not recommended.
.RE

.sp
.ne 2
.na
\fB\fB-p\fR\fR
.ad
.RS 18n
Specifies updating the system file (\fB/kernel/drv/md.conf\fR) with entries
from the \fB/etc/lvm/mddb.cf\fR file. This option is normally used to update a
newly built system before it is booted for the first time. If the system has
been built on a system other than the one where it will run, the location of
the \fBmddb.cf\fR on the local machine can be passed as an argument. The system
file to be updated can be changed using the \fB-k\fR option. This option is for
use with the local diskset only.
.RE

.sp
.ne 2
.na
\fB\fB-s\fR \fIsetname\fR\fR
.ad
.RS 18n
Specifies the name of the diskset on which the \fBmetadb\fR command will work.
Using the \fB-s\fR option will cause the command to perform its administrative
function within the specified diskset. Without this option, the command will
perform its function on local database replicas.
.RE

.sp
.ne 2
.na
\fB\fIslice\fR\fR
.ad
.RS 18n
Specifies the logical name of the physical slice (partition), such as
\fB/dev/dsk/c0t0d0s3\fR.
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fRCreating Initial State Database Replicas
.sp
.LP
The following example creates the initial state database replicas on a new
system.

.sp
.in +2
.nf
# metadb -a -f c0t0d0s7 c0t1d0s3 c1t0d0s7 c1t1d0s3
.fi
.in -2
.sp

.sp
.LP
The \fB-a\fR and \fB-f\fR options force the creation of the initial database
and replicas. You could then create metadevices with these same slices, making
efficient use of the system.

.LP
\fBExample 2 \fRAdding Two Replicas on Two New Disks
.sp
.LP
This example shows how to add two replicas on two new disks that have been
connected to a system currently running Volume Manager.

.sp
.in +2
.nf
# metadb -a c0t2d0s3 c1t1d0s3
.fi
.in -2
.sp

.LP
\fBExample 3 \fRDeleting Two Replicas
.sp
.LP
This example shows how to delete two replicas from the system. Assume that
replicas have been set up on \fB/dev/dsk/c0t2d0s3\fR and
\fB/dev/dsk/c1t1d0s3\fR.

.sp
.in +2
.nf
# metadb -d c0t2d0s3 c1t1d0s3
.fi
.in -2
.sp

.sp
.LP
Although you can delete all replicas, you should never do so while metadevices
still exist. Removing all replicas causes existing metadevices to become
inoperable.

.SH FILES
.sp
.ne 2
.na
\fB\fB/etc/lvm/mddb.cf\fR\fR
.ad
.RS 23n
Contains the location of each copy of the metadevice state database.
.RE

.sp
.ne 2
.na
\fB\fB/etc/lvm/md.tab\fR\fR
.ad
.RS 23n
Workspace file for metadevice database configuration.
.RE

.sp
.ne 2
.na
\fB\fB/kernel/drv/md.conf\fR\fR
.ad
.RS 23n
Contains database replica information for all metadevices on a system. Also
contains Solaris Volume Manager configuration information.
.RE

.SH EXIT STATUS
.sp
.LP
The following exit values are returned:
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 6n
successful completion
.RE

.sp
.ne 2
.na
\fB\fB>0\fR\fR
.ad
.RS 6n
an error occurred
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Stable
.TE

.SH SEE ALSO
.sp
.LP
\fBmdmonitord\fR(1M), \fBmetaclear\fR(1M), \fBmetadetach\fR(1M),
\fBmetahs\fR(1M), \fBmetainit\fR(1M), \fBmetaoffline\fR(1M),
\fBmetaonline\fR(1M), \fBmetaparam\fR(1M), \fBmetarecover\fR(1M),
\fBmetarename\fR(1M), \fBmetareplace\fR(1M), \fBmetaroot\fR(1M),
\fBmetaset\fR(1M), \fBmetassist\fR(1M), \fBmetastat\fR(1M), \fBmetasync\fR(1M),
\fBmetattach\fR(1M), \fBmd.tab\fR(4), \fBmd.cf\fR(4), \fBmddb.cf\fR(4),
\fBmd.tab\fR(4), \fBattributes\fR(5), \fBmd\fR(7D)
.sp
.LP
\fI\fR
.SH NOTES
.sp
.LP
Replicas cannot be stored on fabric-attached storage, SANs, or other storage
that is not directly attached to the system. Replicas must be on storage that
is available at the same point in the boot process as traditional SCSI or IDE
drives. A replica can be stored on a:
.RS +4
.TP
.ie t \(bu
.el o
Dedicated local disk partition
.RE
.RS +4
.TP
.ie t \(bu
.el o
Local partition that will be part of a volume
.RE
.RS +4
.TP
.ie t \(bu
.el o
Local partition that will be part of a UFS logging device
.RE