IBM® DB2 server suspended
I/O support enables you to split mirrored copies of your primary database
without taking the database offline. You can use this to very quickly
create a standby database to take over if the primary database fails.
Disk mirroring is the process of writing data to two separate
hard disks at the same time. One copy of the data is called a mirror
of the other. Splitting a mirror is the process of separating the
two copies.
You can use disk mirroring to maintain a secondary copy of your
primary database. You can use DB2 server suspended I/O functionality
to split the primary and secondary mirrored copies of the database
without taking the database offline. Once the primary and secondary
databases copies are split, the secondary database can take over operations
if the primary database fails.
If you would rather not back up a large database using the DB2
server backup utility, you can make copies from a mirrored image by
using suspended I/O and the split mirror function. This approach also:
- Eliminates backup operation overhead from the production machine
- Represents a fast way to clone systems
- Represents a fast implementation of idle standby failover. There
is no initial restore operation, and if a rollforward operation proves
to be too slow, or encounters errors, reinitialization is very fast.
The
db2inidb command initializes the split mirror
so that it can be used:
- As a clone database
- As a standby database
- As a backup image
This command can only be issued against a split mirror, and
it must be run before the split mirror can be used.
In a partitioned database environment, you do not have to suspend
I/O writes on all database partitions simultaneously. You can suspend
a subset of one or more database partitions to create split mirrors
for performing offline backups. If the catalog partition is included
in the subset, it must be the last database partition to be suspended.
In a partitioned database environment, the
db2inidb command
must be run on every database partition before the split image from
any of the database partitions can be used. The tool can be run on
all database partitions simultaneously using the
db2_all
command. If; however, you are using the
RELOCATE USING option,
you cannot use the
db2_all command to run
db2inidb on
all of the database partitions simultaneously. A separate configuration
file must be supplied for each database partition, that includes
the NODENUM value of the database partition being changed. For example,
if the name of a database is being changed, every database partition
will be affected and the
db2relocatedb command
must be run with a separate configuration file on each database partition.
If containers belonging to a single database partition are being
moved, the
db2relocatedb command only needs to
be run once on that database partition.
Note: Ensure that the split
mirror contains all containers and directories which comprise the
database, including the volume directory. To gather this information,
refer to the DBPATHS administrative view, which shows all the files
and directories of the database that need to be split.
DB2 10.5 for Linux, UNIX, and Windows