NonStop Systems Introduction for H-Series RVUs

Requirements of Real-Time Solutions
NonStop Systems Introduction for H-Series RVUs—540083-001
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Data Security
check the customer’s credit card transaction history, including purchases, refunds, and
exchanges. The real-time software would return a recommendation based on its
examination of the customer’s history. But the recommendation is only as reliable as
the data; any missing or incorrect information in the transaction history could result in
an unreliable recommendation.
If a processor, disk drive, or disk drive controller fails, the dangers to data integrity are
even greater. Many applications, each with multiple concurrent users, could be
executing at the point of failure. These applications could be in the process of updating
hundreds of records on the data store at the moment of failure. If we have no way of
knowing which updates were successful and which ones were not recorded in the data
store, the data store is no longer useful because it no longer reflects the real state of
things.
A real-time solution must ensure that transaction data and data in the data store are
correct and consistent at all times. The need for data integrity imposes these three
requirements:
•
The solution must preserve data as received from the end user or other source
even if a system component fails while the system is processing the data.
•
The solution must back out transactions that cannot transform the data store from
one consistent state to another.
•
The solution must restore the data store to its correct and operational state in the
event of a failure such as a head crash on a disk drive or the loss of a pair of disk
drives.
Data Security
Real-time applications make data resources available to multiple end users of business
applications. Such applications must be able to restrict the use of data resources to a
subset of the total user population, or the business loses control of its resources.
For example, the data store might contain credit card information for an order-entry
application running on an operational system. The server that runs the application that
accesses the data store must provide a security mechanism that prevents
unauthorized users from viewing or altering records.
In addition, the solution must offer a security mechanism that restricts authorized users
to subsets of data. For example, each manager who has access to the database must
be able to view and alter only records that pertain to that manager’s employees.
High Performance
If a real-time solution is to provide anything close to zero latency, the real-time
applications and data store must be able to handle massive workloads without
overwhelming the processing capabilities of the computer system on which the solution
is implemented. Furthermore, as the business grows, the system must be able to