shareddisk(4M) DG/UX R4.11MU05 shareddisk(4M)
NAME
shareddisk - shared disk databases
SYNOPSIS
/etc/shareddisk
DESCRIPTION
The /etc/shareddisk directory contains all of the shared disk
database files used in configuring and maintaining physical disk
sharing. Disk sharing is an additional feature provided with the
AViiON® Distributed Lock Manager for ORACLE Parallel Server
(Trademark) product, which must be purchased separately from the
DG/UX (Trademark) System product. You must have this feature to
successfully make use of the shareddisk databases documented herein.
Each shared disk database file is a plain ASCII text file. Each line
in these files represents a separate database record. The fields of
each record are separated by whitespace (space and/or tab
characters). Blank lines and comment lines beginning with the pound
sign character (`#') are allowed in all shared disk database files.
Every shared disk database file contains a version stamp, normally on
the first line in the file. The version stamp takes the form of a
special comment line, as shown below:
# VERSION=1
Do not change or delete version stamp lines, or add similarly-
formatted lines to the database files. If you do, commands that
administer shared disks may fail.
Although the shared disk database files can be edited manually, we
strongly recommend that you do not do so. Use sysadm(1M) or the
shared disk administrative commands admshareddiskhost(1M) and
admshareddiskdevice(1M) instead. Faulty entries in the databases can
seriously degrade the safety mechanisms built into the shared disk
management subsystem, potentially risking the integrity of data on
shared disk devices. The aforementioned interfaces perform checking
that will help prevent errors from creeping into the databases.
The files within the /etc/shareddisk directory are:
hosts - shared disk hosts database file
This file defines the hosts that form a shared disk "cluster".
It contains information about all remote hosts ("nodes")
sharing physical disks, and may also contain information about
the "local" system upon which the database resides. This file
also defines how the local system should communicate with each
remote system. The admshareddiskhost(1M) command maintains
this database.
The format of entries in the shared disk hosts database file
is as follows:
hostname
The name of a system that shares one or more physical
disk devices with other nodes in the cluster. Both the
name of the local system itself and the names of remote
systems are supported for this field.
communications-path
The type of communications path to the system. Two
values are supported for this field, as described
below.
The communications-path type network identifies an
entry that represents a remote system. Such a system
must be connected to the local system by a local area
network (LAN), as defined by the Transport Layer
Interface (TLI) specification or the Internet
Communications Domain (e.g., TCP/IP) of DG/UX IPC.
The communications-path type localhost identifies an
entry that represents the local system. At most one
such entry is supported within a single instance of the
database.
devices - shared disk devices database file
This file identifies each physical disk on the local system
that can be shared with one or more other systems. Physical
disks listed in the shared disk devices database (but not
necessarily available for shared access at the moment) are
referred to as "public". This file also defines a cluster-
wide name for each public physical disk, which is termed the
"public device name". The admshareddiskdevice(1M) command
maintains this database.
Each entry in the database associates a public device name
with the device specification of a physical disk device that
can be shared among two or more systems. The format of
entries in the shared disk devices database file is as
follows:
name The public device name, an administrator-defined name
for the device entry. Throughout the cluster, every
shared disk devices database entry that represents a
path to the same physical disk device must contain the
same public device name. However, this name must be
unique within a single instance of the database; it is
the key by which records are identified in the
database.
device-spec
The DG/UX Common Device Specification for accessing the
public physical disk on the local system. This field
is usually different between nodes, even between device
entries that represent paths to the same public
physical disk device. However, this field must be
unique within a single instance of the database; no two
entries in one database file may represent the same
physical disk device.
EXAMPLES
For these examples, assume that the nodes "hostA" and "hostB" share a
CLARiiON disk array. The array is configured with two physical disks
as follows:
· The first physical disk has public device name "pdisk1", with
DG/UX Common Device Specifications "sd(dgsc(0,6),0,2)" on hostA
and "sd(dgsc(0,7),0,2)" on hostB.
· The second physical disk has public device name "pdisk2", with
DG/UX Common Device Specifications "sd(dgsc(0,6),0,4)" on hostA
and "sd(dgsc(0,7),0,4)" on hostB.
/etc/shareddisk/hosts
In this example, the shared disk hosts database on hostA would
contain the following entry:
hostB network
The shared disk hosts database on hostB would contain the
corresponding entry:
hostA network
Both databases might also contain an entry for the local host:
hostA localhost
on hostA, and
hostB localhost
on hostB.
/etc/shareddisk/devices
In this example, the shared disk devices database on hostA would
contain two entries, as follows:
pdisk1 sd(dgsc(0,6),0,2)
pdisk2 sd(dgsc(0,6),0,4)
The shared disk devices database on hostB would contain the
corresponding entries:
pdisk1 sd(dgsc(0,7),0,2)
pdisk2 sd(dgsc(0,7),0,4)
FILES
/etc/shareddisk/hosts database of information about communications
with nodes sharing disks in a cluster
/etc/shareddisk/devices database of information about physical disks
that can be shared with other nodes
SEE ALSO
admshareddiskdevice(1M), admshareddiskhost(1M), sysadm(1M).
NOTES
Every system sharing a physical disk with the local system must be
listed in the shared disk hosts database. The local system itself
need be listed in the database only if it is known by a nonstandard
name on the remote nodes; for example, if shared disk communication
should occur over an alternate network (i.e., other than the primary
network on the local system).
The shared disk devices databases on every system sharing a given
physical disk must contain entries assigning the same public device
name to that disk. However, the common device specification in each
such entry must be customized to the configuration of the individual
system.
The above rules do not apply to disks "shared" using failover.
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