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cnxset(8)
NAME
cnxset - Adds or deletes the name of a tie-breaker disk to the
/etc/rc.config file (provided on Production Server configurations only)
SYNOPSIS
/usr/sbin/cnxset [-d disk1[,disk2,disk3]] [-D]
FLAGS
-d disk1[,disk2,disk3]
Specifies the name of one to three raw disk devices. Each disk
should participate in a discrete available server environment
(ASE) service that can fail over to, and run on, either system in
a two-system cluster configuration. You can specify up to three
tie-breaker disks by separating each name with a comma (,).
You cannot specify a Logical Storage Manager (LSM) volume or an
Advanced File System (AdvFS) fileset as a tie-breaker disk.
-D Removes all tie-breaker disks from the local system's
/etc/rc.config file.
DESCRIPTION
The cnxset utility adds or deletes the names of one or more tie-breaker
disks in the CNX_DISK variable to the local system's /etc/rc.config file.
A two-member cluster uses a virtual hub connection between the members to
provide access to Memory Channel hardware. This type of cluster
configuration can partition if the cable is disconnected from either
member. A two-member cluster using a redundant Memory Channel virtual hub
configuration can partition if both Memory Channel cables are disconnected
from either system. A cluster partition can result in unpredictable
behavior, and even corruption of shared data, if it is not detected.
The connection manager allows partitions to be detected, and sometimes
remedied, by requiring you to define a tie-breaker disk for such a
configuration immediately after installing the Production Server software.
(The connection manager and distributed lock manager [DLM] will not run
until you define at least one tie-breaker disk.)
A tie-breaker disk is a raw disk device to which both members have access.
When a virtual hub is in use and a tie-breaker disk is defined, the cluster
requires the presence of either both members or one member and a disk. If
this condition is not met, the connection manager and DLM will not
function.
If you have a two-member virtual hub configuration, follow these steps to
configure the cluster:
1. Set up at least one ASE service that can run on either member and that
includes at least one participating disk.
2. On both members, run the cnxset utility, specifying the names of one
or more raw disk devices participating in the service defined in step
1. For example:
% cnxset -d /dev/rrz10c,/dev/rrz11c,/dev/rrz12c
The cnxset utility places the device names in the local system's
/etc/rc.config file, as follows:
CNX_DISK="/dev/rrz10c,/dev/rrz11c,/dev/rrz12c"
You can still use a tie-breaker disk for its normal purposes. The
connection manager neither reads to nor writes from it.
You can specify up to three tie-breaker disks in the cluster. Specifying
multiple tie-breaker disks helps you eliminate the tie-breaker disk as a
single point of failure in the cluster, which consists of a single
remaining member and its tie-breaker disks. Each disk should participate
in a different ASE service, so that you can take a service off line and not
affect cluster operation.
Note
When two tie-breaker disks are specified, the connection manager
requires one member to be present plus both disks. Any other policy
risks a partition involving two "one member/one tie-breaker"
configurations. Because the two tie-breaker disk configuration
introduces another risk (that is, either of the tie-breaker disks
failing would bring down the cluster), it is not very useful.
When three tie-breakers are specified, the connection manager requires
one member to be present plus two disks. This is the optimal
configuration for systems that require no single point of failure.
To delete tie-breaker disks from a cluster, run the cnxset utility,
specifying the -D flag, on each member system.
EXAMPLES
In the following example, the cnxset utility configures /dev/rrz10c,
/dev/rrz11c, and /dev/rrz12c as tie-breaker disks:
% cnxset -d /dev/rrz10c,/dev/rrz11c,/dev/rrz12c
Verifying: /dev/rrz10c
/dev/rrz10c is reserved by the local ASE
/dev/rrz10c is an acceptable device
Verifying: /dev/rrz11c
/dev/rrz11c is reserved by the local ASE
/dev/rrz11c is an acceptable device
Verifying: /dev/rrz12c
/dev/rrz12c is reserved by the local ASE
/dev/rrz12c is an acceptable device
In the following example, the cnxset utility attempts to configure /dev/tty
as a tie-breaker disk. The utility fails with an appropriate message.
% cnxset -d /dev/tty
Verifying: /dev/tty
/dev/tty is unknown to the local ASE
Performing further checks on this device...
/dev/tty is not a disk. It does not support DEVIOCGET
/dev/tty is not an acceptable device
Unable to configure device /dev/tty
In the following example, the cnxset utility attempts to configure
/dev/rrz0c as a tie-breaker disk. The utility fails with an appropriate
message.
% cnxset -d /dev/rrz0c
Verifying: /dev/rrz0c
/dev/rrz0c is unknown to the local ASE
Performing further checks on this device...
/dev/rrz0c is a disk
/dev/rrz0c will not be used until it is included in an ASE service
/dev/rrz0c is an acceptable device
Local configuration updated...You must also update all other nodes
In the following example, the cnxset utility deletes all tie-breaker disks
from the local system's /etc/rc.config file. You must invoke the utility
with the -D flag on each cluster member to remove the tie-breaker disks
from the cluster.
% cnxset -D
Local configuration updated...You must also update all other nodes
FILES
/usr/sbin/cnxset
Specifies the command path.
/etc/rc.config
Local system's configuration file.
RELATED INFORMATION
cnxagentd(8), cnxmgrd(8), cnxmond(8), cnxpingd(8), cnxshow(8)
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Index for
Section 8 |
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Alphabetical
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Top of
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