metaset(1M) System Administration Commands metaset(1M)NAMEmetaset - 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]
/usr/sbin/metaset [-s setname] -a | -d [ [m] mediator_host_list]
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 actually provide a high-availability environment.
A single-owner disk set configuration manages storage on a SAN or fab‐
ric-attached storage, or provides namespace control and state database
replica management for a specified set of disks.
In a shared disk set configuration, multiple hosts are physically con‐
nected 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 repartitions 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 boundaries 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 fac‐
tors, 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
If the existing partition table does not meet these criteria, 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 device) 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 neces‐
sary, 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 DiskSuite soft‐
ware, 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 cor‐
respondingly 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 Man‐
ager naming conventions. Hot spare pools with shared disk sets use the
following convention:
setname/hspnumber
where setname is the name of the disk set, and number is the number of
the hot spare pool (0-999).
Multi-node Environment
To create and work with a disk set in a multi—node environment, 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 data‐
bases", 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 get‐
ting the wrong replica record on a disk set take. An error message 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 con‐
figuration, referred to as mediators or mediator hosts, run a special
daemon, rpc.metamedd(1M). The mediator hosts take on additional respon‐
sibilities 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 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 interven‐
tion is required to make the data accessible. See mediator(7D) for fur‐
ther details.
Use the -m option to add or delete a mediator host. See OPTIONS.
OPTIONS
The following options are supported:
-a
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 repartioned. 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 prob‐
lems, or is administratively down, the add fails.
-a | -d | -m mediator_host_list
Add (-a) or delete (-d) mediator hosts to the specified disk set. A
mediator_host_list 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 argu‐
ment to -m to delete a mediator host.
In a single metaset command you can add or delete three mediator
hosts. See EXAMPLES.
-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 single 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 repli‐
cas matches the replica layout algorithm.
-C {take | release | purge}
Do not interact with the Cluster Framework when used in a Sun Clus‐
ter 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. This option is not for use with a
multi-owner disk set.
take
Take ownership of the disk set but do not inform the Cluster
Framework that the disk set is available
release
Release ownership of the disk set without informing the Cluster
Framework. This option should only be used if the disk set own‐
ership was taken with the corresponding -C take option.
purge
Remove the disk set without informing the Cluster Framework
that the disk set has been purged
-d
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.
This option fails on a multi-owner disk set if attempting to with‐
draw 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 ownership. 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 specified
with a partial list of hosts, it can be used for one-host adminis‐
tration. One-host administration could be useful when a host is
known to be non-functional, thus avoiding timeouts and failed com‐
mands. 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 per‐
formed.
-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 can‐
not 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 con‐
cepts of take and release, used with traditional 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 hap‐
pens automatically in a cluster or single-node sitatu‐
ion.
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 reconfigura‐
tion, 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 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 reparti‐
tioned using the standard Solaris Volume Manager algorithm. See
DESCRIPTION.
-l length
Set the size (in blocks) for the metadevice state database 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 ownership of the
set, use the -P option.
This option is not for use with a multi-owner disk set.
-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 set‐
name 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 metade‐
vices 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 operations permitted are the addition and deletion of
replicas. 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 tag‐
number.
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 cancels all resyncs running on the node. A
cluster reconfiguration process that is removing a node from the
cluster 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, respectively. (The hostname is
found in /etc/nodename.) Adding the 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:
# 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 host‐
name 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
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWmdu │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOmdmonitord(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), 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.
SunOS 5.10 20 Feb 2009 metaset(1M)
