Availability Guide for Change Management

Reducing the Time Required for Planned Outages
Availability Guide for Change Management–125506
6-8
Reducing Downtime When Installing a New
Operating System
Reducing Downtime When Installing a New
Operating System
Tandem currently requires that you shut down your NonStop system to install any major
operating system release and some critical IPMs. Using DSM/SCM minimizes your
system down time in the following ways:
•
By requiring you to stop only applications being updated.
Although the safest practice is to stop all applications, this may be unnecessary in
cases where only a few files have changed. Stopping only the changed applications
minimizes down time.
•
By placing files under “fabricated” names.
When you apply software to a target system, DSM/SCM places the product files in
their destination target subvolumes (TSVs) with “fabricated” file names, that is, file
names that are not the actual product file names used on the target system.
DSM/SCM uses fabricated file names so that the files it has just placed do not
conflict with the file names of currently running programs on the target system.
After stopping the affected applications, you run the DSM/SCM utility, ZPHIRNM,
to rename the files to their real names.
•
By requiring a system load only if necessary.
DSM/SCM determines whether a system load is necessary.
Testing Your Plans
Testing should include recovery procedures in case problems occur with the new
version. These tests also provide a good opportunity to evaluate various ways to reduce
startup and shutdown time.
Section 2, “Change Control,” describes a change-control process that includes how to
create recovery procedures. A change-control process is a process for proposing,
planning, and implementing change. An efficient change-control process ensures the
successful migration of a system or an application environment from one stable
configuration to another.
The Introduction to NonStop Operations Management includes information about
recovery planning that can help you develop testing procedures.