System Administration Commands metaset(1M)
NAME
metaset - configure disk sets
SYNOPSIS
/usr/sbin/metaset -s setname [-M-a -h hostname]
/usr/sbin/metaset -s setname -A {enable disable}
/usr/sbin/metaset -s setname [-A {enable disable}] -a -h hostname...
/usr/sbin/metaset -s setname -a [-l length] [-L] drivename...
/usr/sbin/metaset -s setname -C {take release purge}
/usr/sbin/metaset -s setname -d [-f] -h hostname...
/usr/sbin/metaset -s setname -d [-f] drivename...
/usr/sbin/metaset -s setname -j
/usr/sbin/metaset -s setname -r
/usr/sbin/metaset -s setname -w
/usr/sbin/metaset -s setname -t [-f] [-u tagnumber] [y]
/usr/sbin/metaset -s setname -b
/usr/sbin/metaset -s setname -P
/usr/sbin/metaset -s setname -q
/usr/sbin/metaset -s setname -o [-h hostname]
/usr/sbin/metaset [-s setname]
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/usr/sbin/metaset [-s setname] -a -d
[ [m] mediatorhostlist]
DESCRIPTION
The metaset command administers sets of disks in named disk
sets. Named disk sets include any disk set that is not in
the local set. While disk sets enable a high-availability
configuration, Solaris Volume Manager itself does not actu-
ally provide a high-availability environment.
A single-owner disk set configuration manages storage on a
SAN or fabric-attached storage, or provides namespace con-
trol and state database replica management for a specified
set of disks.
In a shared disk set configuration, multiple hosts are phy-
sically connected to the same set of disks. When one host
fails, another host has exclusive access to the disks. Each
host can control a shared disk set, but only one host can
control it at a time.
When you add a new disk to any disk set, Solaris Volume
Manager checks the disk format. If necessary, it reparti-
tions the disk to ensure that the disk has an appropriately
configured reserved slice 7 (or slice 6 on an EFI labelled
device) with adequate space for a state database replica.
The precise size of slice 7 (or slice 6 on an EFI labelled
device) depends on the disk geometry. For tradtional disk
sets, the slice is no less than 4 Mbytes, and probably
closer to 6 Mbytes, depending on where the cylinder boun-
daries lie. For multi-owner disk sets, the slice is a
minimum of 256 Mbytes. The minimal size for slice 7 might
change in the future. This change is based on a variety of
factors, including the size of the state database replica
and information to be stored in the state database replica.
For use in disk sets, disks must have a dedicated slice (six
or seven) that meets specific criteria:
o The slice must start at sector 0
o The slice must include enough space for disk label
o The state database replicas cannot be mounted
o The slice does not overlap with any other slices,
including slice 2
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If the existing partition table does not meet these cri-
teria, or if the -L flag is specified, Solaris Volume
Manager repartitions the disk. A small portion of each drive
is reserved in slice 7 (or slice 6 on an EFI labelled dev-
ice) for use by Solaris Volume Manager. The remainder of the
space on each drive is placed into slice 0. Any existing
data on the disks is lost by repartitioning.
After you add a drive to a disk set, it can be repartitioned
as necessary, with the exception that slice 7 (or slice 6 on
an EFI labelled device) is not altered in any way.
After a disk set is created and metadevices are set up
within the set, the metadevice name is in the following
form:
/dev/md/setname/{dsk,rdsk}/dnumber
where setname is the name of the disk set, and number is the
number of the metadevice (0-127).
If you have disk sets that you upgraded from Solstice Disk-
Suite software, the default state database replica size on
those sets is 1034 blocks, not the 8192 block size from
Solaris Volume Manager. Also, slice 7 on the disks that were
added under Solstice DiskSuite are correspondingly smaller
than slice 7 on disks that were added under Solaris Volume
Manager.
If disks you add to a disk set have acceptable slice 7s
(that start at cylinder 0 and that have sufficient space for
the state database replica), they are not reformatted.
Hot spare pools within local disk sets use standard Solaris
Volume Manager naming conventions. Hot spare pools with
shared disk sets use the following convention:
setname/hotsparepool
where setname is the name of the disk set, and
hotsparepool is the name of the hot spare pool associated
with the disk set.
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Multi-node Environment
To create and work with a disk set in a multi-node environ-
ment, root must be a member of Group 14 on all hosts, or the
/.rhosts file must contain an entry for all other host
names. This is not required in a SunCluster 3.x enviroment.
Tagged data
Tagged data occurs when there are different versions of a
disk set's replicas. This tagged data consists of the set
owner's nodename, the hardware serial number of the owner
and the time it was written out to the available replicas.
The system administer can use this information to determine
which replica contains the correct data.
When a disk set is configured with an even number of storage
enclosures and has replicas balanced across them evenly, it
is possible that up to half of the replicas can be lost (for
example, through a power failure of half of the storage
enclosures). After the enclosure that went down is rebooted,
half of the replicas are not recognized by SVM. When the set
is retaken, the metaset command returns an error of "stale
databases", and all of the metadevices are in a read-only
state.
Some of the replicas that are not recognized need to be
deleted. The action of deleting the replicas also causes
updates to the replicas that are not being deleted. In a
dual hosted disk set environment, the second node can access
the deleted replicas instead of the existing replicas when
it takes the set. This leads to the possibility of getting
the wrong replica record on a disk set take. An error mes-
sage is displayed, and user intervention is required.
Use the -q to query the disk set and the -t, -u, and -y,
options to select the tag and take the disk set. See
OPTIONS.
Mediator Configuration
SVM provides support for a low-end HA solution consisting of
two hosts that share only two strings of drives. The hosts
in this type of configuration, referred to as mediators or
mediator hosts, run a special daemon, rpc.metamedd(1M). The
mediator hosts take on additional responsibilities to ensure
that data is available in the case of host or drive
failures.
A mediator configuration can survive the failure of a single
host or a single string of drives, without administrative
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intervention. If both a host and a string of drives fail
(multiple failures), the integrity of the data cannot be
guaranteed. At this point, administrative intervention is
required to make the data accessible. See mediator(7D) for
further details.
Use the -m option to add or delete a mediator host. See
OPTIONS.
OPTIONS
The following options are supported:
-a drivename
Add drives or hosts to the named set. For a drive to be
accepted into a set, the drive must not be in use within
another metadevice or disk set, mounted on, or swapped
on. When the drive is accepted into the set, it is
repartitioned and the metadevice state database replica
(for the set) can be placed on it. However, if a slice 7
(or slice 6 on an EFI labelled device), starts at
cylinder 0, and is large enough to hold a state database
replica, then the disk is not repartitioned. Also, a
drive is not accepted if it cannot be found on all hosts
specified as part of the set. This means that if a host
within the specified set is unreachable due to network
problems, or is administratively down, the add fails.
Specify a drive name in the form cnumtnumdnum. Do not
specify a slice number (snum). For drives in a Sun Clus-
ter, you must specify a complete pathname for each
drive. Such a name has the form:
/dev/did/[r]dsk/dnum
-a -d -m mediatorhostlist
Add (-a) or delete (-d) mediator hosts to the specified
disk set. A mediatorhostlist is the nodename(4) of the
mediator host to be added and (for adding) up to two
other aliases for the mediator host. The nodename and
aliases for each mediator host are separated only by
commas. Up to three mediator hosts can be specified for
the named disk set. Specify only the nodename of that
host as the argument to -m to delete a mediator host.
In a single metaset command you can add or delete up to
three mediator hosts. See EXAMPLES.
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-A {enable disable}
Specify auto-take status for a disk set. If auto-take is
enabled for a set, the disk set is automatically taken
at boot, and file systems on volumes within the disk set
can be mounted through /etc/vfstab entries. Only a sin-
gle host can be associated with an auto-take set, so
attempts to add a second host to an auto-take set or
attempts to configure a disk set with multiple hosts as
auto-take fails with an error message. Disabling auto-
take status for a specific disk set causes the disk set
to revert to normal behavior. That is, the disk set is
potentially shared (non-concurrently) among hosts, and
unavailable for mounting through /etc/vfstab.
-b
Insure that the replicas are distributed according to
the replica layout algorithm. This can be invoked at any
time, and does nothing if the replicas are correctly
distributed. In cases where the user has used the metadb
command to manually remove or add replicas, this command
can be used to insure that the distribution of replicas
matches the replica layout algorithm.
-C {take release purge}
Do not interact with the Cluster Framework when used in
a Sun Cluster 3 environment. In effect, this means do
not modify the Cluster Configuration Repository. These
options should only be used to fix a broken disk set
configuration.
take
Take ownership of the disk set but do not inform the
Cluster Framework that the disk set is available.
This option is not for use with a multi-owner disk
set.
release
Release ownership of the disk set without informing
the Cluster Framework. This option should only be
used if the disk set ownership was taken with the
corresponding -C take option. This option is not for
use with a multi-owner disk set.
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purge
Remove the disk set without informing the Cluster
Framework that the disk set has been purged. This
option should only be used when the disk set is not
accessible and requires rebuilding.
-d drivename
Delete drives or hosts from the named disk set. For a
drive to be deleted, it must not be in use within the
set. The last host cannot be deleted unless all of the
drives within the set are deleted. Deleting the last
host in a disk set destroys the disk set.
Specify a drive name in the form cnumtnumdnum. Do not
specify a slice number (snum). For drives in a Sun Clus-
ter, you must specify a complete pathname for each
drive. Such a name has the form:
/dev/did/[r]dsk/dnum
This option fails on a multi-owner disk set if attempt-
ing to withdraw the master node while other nodes are in
the set.
-f
Force one of three actions to occur: takes ownership of
a disk set when used with -t; deletes the last disk
drive from the disk set; or deletes the last host from
the disk set. Deleting the last drive or host from a
disk set requires the -d option.
When used to forcibly take ownership of the disk set,
this causes the disk set to be grabbed whether or not
another host owns the set. All of the disks within the
set are taken over (reserved) and fail fast is enabled,
causing the other host to panic if it had disk set own-
ership. The metadevice state database is read in by the
host performing the take, and the shared metadevices
contained in the set are accessible.
You can use this option to delete the last drive in the
disk set, because this drive would implicitly contain
the last state database replica.
You can use -f option to delete hosts from a set. When
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specified with a partial list of hosts, it can be used
for one-host administration. One-host administration
could be useful when a host is known to be non-
functional, thus avoiding timeouts and failed commands.
When specified with a complete list of hosts, the set is
completely deleted. It is generally specified with a
complete list of hosts to clean up after one-host
administration has been performed.
-h hostname...
Specify one or more host names to be added to or deleted
from a disk set. Adding the first host creates the set.
The last host cannot be deleted unless all of the drives
within the set have been deleted. The host name is not
accepted if all of the drives within the set cannot be
found on the specified host. The host name is the same
name found in /etc/nodename.
-j
Join a host to the owner list for a multi-owner disk
set. The concepts of take and release, used with tradi-
tional disk sets, do not apply to multi-owner sets,
because multiple owners are allowed.
As a host boots and is brought online, it must go
through three configuration levels to be able to use a
multi-owner disk set:
1. It must be included in the cluster nodelist,
which happens automatically in a cluster or
single-node sitatuion.
2. It must be added to the multi-owner disk set
with the -a -h options documented elsewhere in
this man page
3. It must join the set. When the host is first
added to the set, it is automatically joined.
On manual restarts, the administrator must manually
issue
metaset -s multinodesetname -j
to join the host to the owner list. After the cluster
reconfiguration, when the host reenters the cluster, the
node is automatically joined to the set. The metaset -j
command joins the host to all multi-owner sets that the
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host has been added to. In a single node situation,
joining the node to the disk set starts any necessary
resynchronizations.
-L
When adding a disk to a disk set, force the disk to be
repartitioned using the standard Solaris Volume Manager
algorithm. See DESCRIPTION.
-l length
Set the size (in blocks) for the metadevice state data-
base replica. The length can only be set when adding a
new drive; it cannot be changed on an existing drive.
The default (and maximum) size is 8192 blocks, which
should be appropriate for most configurations. Replica
sizes of less than 128 blocks are not recommended.
-M
Specify that the disk set to be created or modified is a
multi-owner disk set that supports multiple concurrent
owners.
This option is required when creating a multi-owner disk
set. Its use is optional on all other operations on a
multi-owner disk set and has no effect. Existing disk
sets cannot be converted to multi-owner sets.
-o
Return an exit status of 0 if the local host or the host
specified with the -h option is the owner of the disk
set.
-P
Purge the named disk set from the node on which the
metaset command is run. The disk set must not be owned
by the node that runs this command. If the node does own
the disk set, the command fails.
If you need to delete a disk set but cannot take owner-
ship of the set, use the -P option.
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-q
Displays an enumerated list of tags pertaining to
``tagged data'' that can be encountered during a take of
the ownership of a disk set.
This option is not for use with a multi-owner disk set.
-r
Release ownership of a disk set. All of the disks within
the set are released. The metadevices set up within the
set are no longer accessible.
This option is not for use with a multi-owner disk set.
-s setname
Specify the name of a disk set on which metaset works.
If no setname is specified, all disk sets are returned.
-t
Take ownership of a disk set safely. If metaset finds
that another host owns the set, this host is not be
allowed to take ownership of the set. If the set is not
owned by any other host, all the disks within the set
are owned by the host on which metaset was executed. The
metadevice state database is read in, and the shared
metadevices contained in the set become accessible. The
-t option takes a disk set that has stale databases.
When the databases are stale, metaset exits with code
66, and prints a message. At that point, the only opera-
tions permitted are the addition and deletion of repli-
cas. Once the addition or deletion of the replicas has
been completed, the disk set should be released and
retaken to gain full access to the data.
This option is not for use with a multi-owner disk set.
-u tagnumber
Once a tag has been selected, a subsequent take with -u
tagnumber can be executed to select the data associated
with the given tagnumber.
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w
Withdraws a host from the owner list for a multi-owner
disk set. The concepts of take and release, used with
traditional disk sets, do not apply to multi-owner sets,
because multiple owners are allowed.
Instead of releasing a set, a host can issue
metaset -s multinodesetname -w
to withdraw from the owner list. A host automatically
withdraws on a reboot, but can be manually withdrawn if
it should not be able to use the set, but should be able
to rejoin at a later time. A host that withdrew due to a
reboot can still appear joined from other hosts in the
set until a reconfiguration cycle occurs.
metaset -w withdraws from ownership of all multi-owner
sets of which the host is a member. This option fails if
you attempt to withdraw the master node while other
nodes are in the disk set owner list. This option can-
cels all resyncs running on the node. A cluster reconfi-
guration process that is removing a node from the clus-
ter membership list effectively withdraws the host from
the ownership list.
-y
Execute a subsequent take. If the take operation
encounters ``tagged data,'' the take operation exits
with code 2. You can then run the metaset command with
the -q option to see an enumerated list of tags.
EXAMPLES
Example 1 Defining a Disk Set
This example defines a disk set.
# metaset -s relo-red -a -h red blue
The name of the disk set is relo-red. The names of the first
and second hosts added to the set are red and blue, respec-
tively. (The hostname is found in /etc/nodename.) Adding the
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first host creates the disk set. A disk set can be created
with just one host, with the second added later. The last
host cannot be deleted until all of the drives within the
set have been deleted.
Example 2 Adding Drives to a Disk Set
This example adds drives to a disk set.
# metaset -s relo-red -a c2t0d0 c2t1d0 c2t2d0 c2t3d0 c2t4d0 c2t5d0
The name of the previously created disk set is relo-red. The
names of the drives are c2t0d0, c2t1d0, c2t2d0, c2t3d0,
c2t4d0, and c2t5d0. There is no slice identifier ("sx") at
the end of the drive names.
Example 3 Adding Multiple Mediator Hosts
The following command adds three mediator hosts to the
specified disk set.
# metaset -s mydiskset -a -m myhost1,alias1 myhost2,alias2 myhost3,alias3
Example 4 Purging a Disk Set from the Node
The following command purges the disk set relo-red from the
node:
# metaset -s relo-red -P
Example 5 Querying a Disk Set for Tagged Data
The following command queries the disk set relo-red for a
list of the tagged data:
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# metaset -s relo-red -q
This command produces the following results:
The following tag(s) were found:
1 - vha-1000c - Fri Sep 20 17:20:08 2002
2 - vha-1000c - Mon Sep 23 11:01:27 2002
Example 6 Selecting a tag and taking a Disk set
The following command selects a tag and takes the disk set
relo-red:
# metaset -s relo-red -t -u 2
Example 7 Defining a Multi-Owner Disk Set
The following command defines a multi-owner disk set:
# metaset -s blue -M -a -h hahost1 hahost2
The name of the disk set is blue. The names of the first and
second hosts added to the set are hahost1 and hahost2,
respectively. The hostname is found in /etc/nodename. Adding
the first host creates the multi-owner disk set. A disk set
can be created with just one host, with additional hosts
added later. The last host cannot be deleted until all of
the drives within the set have been deleted.
FILES
/etc/lvm/md.tab
Contains list of metadevice configurations.
EXIT STATUS
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The following exit values are returned:
0
Successful completion.
>0
An error occurred.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWmdu
Interface Stability Stable
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), metastat(1M),
metasync(1M), metattach(1M), md.tab(4), md.cf(4),
mddb.cf(4), md.tab(4), attributes(5), md(7D)
NOTES
Disk set administration, including the addition and deletion
of hosts and drives, requires all hosts in the set to be
accessible from the network.
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