Chapter 2. DB2 server deployment 41
Other file system technologies that provide concurrent access to a common set
of files can also be used in creating the instance home directory in a DB2
partitioned database system. The IBM General Parallel File System™ (GPFS™)
is an example. It is a high performance scalable file management solution
available on both AIX and Linux. For more information about GPFS, refer to:
http://www.ibm.com/systems/clusters/software/gpfs/index.html
Remote shell
For a partitioned database system on the UNIX/Linux platforms, a remote shell
utility is required to issue commands to every partition. DB2 9.5 supports two
remote utilities:
򐂰rsh
򐂰ssh
Remote Shell (rsh) is a traditional shell utility that has been supported by DB2 for
many years. It is the default shell tool used by DB2 after the installation. It allows
the user to execute commands from another computer over the network. But rsh
could be considered an insecure utility because it does not provide strong
encryption when sending information over a network.
Security Shell (ssh) could be taken as an improved version of remote shell. It
uses public-key technology to encrypt and decrypt messages and to authenticate
a remote user who requests to access a local machine. It is just as flexible as
rsh. Support for ssh was introduced in DB2 V8.2.
Users and groups in a partitioned database environment
There is not much difference between a multi-partitioned database and a
single-partitioned database in regard to users and groups. Three users and their
groups have to be created on each participating machine. For the instance user
and the fenced user, not only the name of the user or group, but also the user ID
or the group ID, must be identical on each machine.
For the Administration user, it also has to be created on each participating
computer, not just the instance owning one, to allow administrative tasks to be
performed on that computer.
Note: Unlike UNIX and Linux, we do not have to configure remote shell for
DB2 on Windows. There is a DB2 service automatically installed to support
remote DB2 command executions. It is called DB2 Remote Command Server.