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COM3310 > Textbook Questions > Flashcards

Textbook Questions Flashcards

1
Q

List ways in which the mainframe of today challenges the traditional thinking about centralized computing versus distributed computing.

A
  • Centralising data in a single mainframe repository saves customers from having to manage updates to more than one copy of their business data
  • Distinction between distributed and centralised is blurring as smaller machines continue to gain in processing power and mainframes become more flexible and multi-purpose.
  • Mainframes are now frequently used in combination with networks of smaller servers
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2
Q

Explain how businesses make use of mainframe processing power, and how mainframe computing differs from other types of computing.

A
  • RAS (Reliable, Available, Serviceable)
  • Secure
  • Allow for huge numbers of users to rapidly access the same data without interfering
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3
Q

What are four different operating systems that run on the mainframe.

A
  • z/VM
  • z/VSE
  • Linux on IBM System Z
  • z/TPF
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4
Q

What is a mainframe today?

A

“A mainframe is what businesses use to host the commercial databases, transaction servers, and applications that require a greater degree of security and availability than is commonly found on smaller-scale machines.”

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5
Q

Describe how running a mainframe can be cost effective, given the large number of roles needed to run a mainframe system.

A
  • Centralised
  • Environmentally friendly
  • Support staff seem comparatively small when compared to the amount of transactions they manage
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6
Q

How is today’s mainframe environment-friendly? Discuss with examples

A

The mainframe’s virtualization uses the power of many servers using a small hardware footprint. Today’s mainframe reduces the impact of energy cost to a near-negligible value when calculated on a per logical server basis because more applications, several hundred of them, can be deployed on a single machine.

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7
Q

Why does software pricing for mainframes seem so complex?

A
  • Software licences for applications are often set by vendors on the total power of the machine even if it only uses 1% of their power (often the case for older applications)
  • As an offset to this cost, mainframe can offer extreme virtualisation that allows you to run multiple copies of these programs on the same processors
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8
Q

Why does IBM have so many models (or “capacity settings”) for recent mainframe machines?

A

To meet business requirements and manage a customer’s growth

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9
Q

Multiprocessing means running several processors simultaneously (available to the operating system and applications). What does multiprogramming mean?

A
  • Executing many programs concurrently
  • With multiprogramming, when a job cannot use the processor, the system can suspend, or interrupt the job, freeing the processor to work on another job
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10
Q

What are the differences between loosely coupled systems and tightly coupled systems?

A
  • Loosely coupled systems: Configurations with shared DASD, CTC connections, and shared job queues
  • Tightly coupled systems: Multiprocessors, where several processors are used by the operating system
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11
Q

What z/OS application changes are needed for it to work in an LPAR?

A

You can run several different operating systems within a single mainframe by partitioning the resources into isolated servers

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12
Q

What z/OS application changes are needed to work in a Parallel Sysplex?

A

Synchronising the Time of Day clocks of multiple servers, which allows events occurring on different servers to be properly sequenced in time.

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13
Q

How do disaster recovery solutions benefit a global business?

A
  • Continuous availability
  • Mirror critical data
  • Efficiently balances workload between sites
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14
Q

What are the advantages of a Parallel Sysplex presenting a single image externally?

A

Brings reduced complexity from both operational and definition perspectives

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15
Q

Why is continuous availability required in today’s marketplace?

A

24/7 systems accessed globally in different timezones

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16
Q

How might someone justify the cost of the “redundant” hardware required to build a Parallel Sysplex?

A

Allow for fallbacks if ‘live’ hardware fails

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17
Q

To display the CPU configuration:

a. Access SDSF from the ISPF primary option menu.
b. In the command input field, enter /D M=CPU and press Enter.
c. Use the ULOG option in SDSF to view the command display result.

A

B

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18
Q

To display the page data set usage:

a. In the command input field, enter /D ASM and press Enter.
b. Press PF3 to return to the previous screens.

A

A

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19
Q

To display information about the current Initial Program Load (IPL):

a. Use ULOG option in SDSF to view the command display result.
b. In the command input field, enter /D IPLINFO and press Enter.

A

B

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20
Q

How does z/OS differ from a single-user operating system? Give two examples.

A
  • Single-User would read in one job, find the data and devices the job needed, let the job run to completion, and then read in another job – z/OS is capable of multiprogramming
  • z/OS allows for many users to make many actions at the same time
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21
Q

z/OS is designed to take advantage of what mainframe architecture? In what year was it introduced?

A

z/OS is designed to take advantage of the IBM System z architecture or z/Architecture, which was introduced in the year 2000

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22
Q

List the three major types of storage used by z/OS.

A
  • Direct Access Storage Devices (DASD)
  • Magnetic Tape Drives
  • Processor Storage (Central Storage)
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23
Q

What is “virtual” about virtual storage?

A

It is not the actual amount of storage available, but instead is the amount of storage dedicated to specific OS or applications that the OS or applications believe this is the full resource

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24
Q
  1. Match the following terms:
    a. Page __ auxiliary storage
    b. Frame __ virtual storage
    c. Slot __ central storage
A

a. Page Virtual Storage
b. Frame Central Storage
c. Slot Auxiliary Storage

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25
Q

What role does workload management play in a z/OS system?

A
  • Controls system resources
  • Aiming to achieve business goals and optimal use of system resources by assigning sysplex resources based on importance and goals
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26
Q

List several defining characteristics of the z/OS operating system.

A
  • An address space (virtual storage)
  • Two types of physical storage: Central and Auxiliary
  • z/OS controls the programs ran based on priority (workload management)
  • Security
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27
Q

List three types of software products that might be added to z/OS to provide a complete system.

A
  • Transaction processors
  • Database systems
  • Web application servers
28
Q

List several differences and similarities between the z/OS and UNIX operating systems.

A
  • Similar: Process multiple instances of work concurrently
  • Different: Virtual storage is assigned with address space within z/OS where as users get whatever virtual storage they need to with UNIX
29
Q

Which of the following is/are not considered to be middleware in a z/OS system?

a. Web servers.
b. Transaction managers.
c. Database managers.
d. Auxiliary storage manager.

A

D

30
Q

The first three character optional software component identifiers tells you which of the following?

a. The software component writing the message.
b. The version of the operating system on which you are running.
c. The release of the software writing the message.
d. None of the above.

A

A

31
Q

If a system service represented by a service request block (SRB) experiences a problem, which is most correct?

a. The system gives control to the recovery routine for the service.
b. The service loops until the operator CANCELs the task.
c. The system service does not experience any problems.
d. The Recovery Termination Manager (RTM) is called to end the service.

A

A

32
Q

What optional means are used to accelerate certain types of workloads running on System z?

a. Use of Service Classes within Workload Manager to classify work.
b. Enabling Specialty Engines to off load specific functions.
c. Using zEnterprise BladeCenter Extension (zBX) optimizers to speed up certain instruction sets.
d. All of the above.

A

C

33
Q

If you want more information about a specific ISPF panel or help with a user error, what should be your first action?

A

Press PF1

34
Q

Name the two z/OS UNIX interactive interfaces and explain the two.

A
  • ISHELL: Good starting point for users familiar with TSO and ISPF, includes panels for mounting and unmounting file systems and doing UNIX administration
  • OMVS: Good starting point for UNIX users, used to invoke the z/OS UNIX shell
35
Q

What is a data set?

A

A collection of logically related data records, such as a library of macros, medical records or a source program

36
Q

What are the three different type of data sets used on z/OS?

A
  • Sequential: Data items that are stored consecutively e.g. alphabetical list of names in a classroom
  • Partitioned: consists of a directory and members, the directory holds the address of each member and thus makes it possible for programs or the operating system to access each member directly
  • Virtual Storage Access Method (VSAM): In a VSAM, Key Sequenced Data Set (KSDS) records are data items that are stored with keys so that the system can retrieve an item without searching all preceding items in the set. VSAM is ideal for data items that are used frequently and in an unpredictable order
37
Q

Why are unique data set names needed by z/OS?

A

The basic z/OS file structure is not hierarchial, z/OS data sets have no equivalent to a path name

38
Q

Why is a PDS used?

A

The directory holds the address of each member and thus makes it possible for programs or the operating system to access each member directly

39
Q

What determines the largest file a traditional UNIX system can use? Is there an equivalent limit for z/OS?

A

z/OS UNIX files are different from the typical z/OS data sets because they are byte-oriented rather than record-oriented

40
Q

What special characters are used to identify a temporary data set in a JCL stream?

A

If you begin your data set name with &&, the JCL processor will allocate it as a temporary data set and delete it when the job has completed

41
Q

What information about a data set is stored in a catalog?

A

Describes data set attributes and indicates the volumes on which a data set is located

42
Q

What is the difference between the master catalog and a user catalog?

A
  • A z/OS system always has at least one master catalog. If it had a single catalog, this catalog would be the master catalog and it would hold the location entries for all data sets, although this would not be efficient
  • The master catalog usually stores only the name of the user catalogs
  • A user catalog is a data set used to locate the DASD colume in which the requested data set is stored
43
Q 
We have three DD statements:
//DD1 DD UNIT=3480,...
//DD2 DD UNIT=0560,...
//DD3 DD UNIT=560,...
What do these numbers mean? How do we know this?
A
  • System disk, tape, special device type, or esoteric (local name)
  • Because it says so in the book
44
Q

JCL can be submitted or started. What is the difference?

A

It is possible to submit JCL for batch processing or start a JCL procedure to start a task

45
Q

Which JCL statement (JOB, EXEC, or DD) has the most parameters? Why?

A

DD, as it can be involved with many aspects of defining or describing attributes of the program inputs or outputs

46
Q

What is the difference between JCL and a JCL PROC? What is the benefit of using a JCL PROC?

A

JCL PROC (Procedure) is like a macro (or method), it contains part of the JCL code that will be repeated and used again to call in the future

47
Q

To override a JCL PROC statement in the JCL stream executing the PROC, what PROC names must be known? What is the order of the names on the JCL override statement?

A
  • An override statement has the following form:
    //stepname.ddname DD
    e.g. //MYSORT.SORTOUT DD
  • The Step Name and the DD name
48
Q

When a JCL job has multiple EXEC statements, what is the type of name associated with each EXEC statement?

A
  • EXEC: JCL that gives the name of a program to be executed

- Following the EXEC is either PGM=(executable program name) or a JCL procedure name

49
Q

What is batch processing?

A

Batch processing is for those frequently used programs that can be executed with minimal human interaction. They are typically executed at a scheduled time or on an as-needed basis.

50
Q

Why does z/OS need a JES?

A

To receive, schedule and output jobs i.e. manage

51
Q

What does the acronym spool stand for?

A
  • Simultaneous Peripheral Operations OnLine
  • Spooling: The reading and writing (by JES) of input and output streams on auxiliary storage devices concurrently with job execution
52
Q

What are some of the jobs performed by an initiator?

A
  • Ensure there are no conflicts sue to data set utilization
  • Ensure that single-user devices, such as tape drives, are allocated correctly
  • Find the executable programs requested for the job
  • Clean up after the job ends and then request the next job
53
Q

Why are multitasking and multithreading important to online transaction processing?

A
  • Allow for more than one task to be processed at the same time, with each task saving its specific variable data and keeping track of the instructions each user is executing
  • Multithreading is different from multitasking in a sense that multitasking allows multiple tasks at the same time, whereas, the Multithreading allows multiple threads of a single task (program, process) to be processed by CPU at the same time.
54
Q

What are some common characteristics of an online transaction system?

A
  • Interactions between the user and the system are brief
  • Managing and dispatching tasks
  • Controlling user access authority to system resources
  • Managing the use of memory
  • Managing and controlling simultaneous access to data files
  • Providing device independence
55
Q

Explain two-phase commit.

A
  • The two-phase commit protocol provides commit and rollback. It verifies that either all changes or no changes are applied even if one of the elements (such as the application, the system, or the resource manager) fails.
  • The protocol allows for restart and recovery processing to take place after the system or subsystem failure
56
Q

How might the meaning of “business transaction” differ from “CICS transaction”?

A
  • A business transaction is a self-contained business deal

- A CICS transaction is a piece of processing initiated by a single request.

57
Q

How do you define resources in CICS?

A
  • CICS manages the sharing of resources

- CICS allows you to keep your application logic separate from your application resources

58
Q

What DB2 objects define a physical storage area?

A

Table Spaces & Index Spaces

59
Q

What are some of the problems with the following SQL statement:
SELECT *
FROM PAYROLL;

A
  • Need to use a semicolon at the end of all statements

- Need to define the user when noting the table e.g. she0001.payroll

60
Q

How does the precompiler find an SQL statement in a program?

A
  • The precompiler identifies the SQL by using special beginning and ending flags that must be included for each SQL statement
  • The beginning flag, EXEC SQL, is the same for all programming languages
  • The ending flag differs: COBOL uses END-EXEC. While C and other languages use a semi-colon
61
Q

How is a load module put back together using the SQL statements?

A

When you execute your application program, the load module is loaded into main storage. When an SQL statement is encountered, the CALL to DB2, which replaced the SQL statement, passes its parameters to DB2.

62
Q

How could you discover what access path the optimizer chooses? What process creates this path?

A
  • The ‘BIND’ process completes this path
  • DB2 has a component called the optimizer, which assesses all the different ways that your data can be accessed, such as scanning an entire table, using an index. It weights the costs of each and picks the least.
63
Q

What is a stored procedure?

A
  • A stored procedure is a user-written application program that typically is stored and run on the server (but it can be run for local purposes as well).
  • You can think of a stored procedure as being somewhat like a subroutine that can be called to perform a set of related functions. It is an application program, but is defined to DB2 and managed by the DB2 subsystem.
64
Q

What are some of the ways that security is handled by DB2?

A

Sensitive data can be isolated in a separate View that prevents unauthorized applications from seeing it

65
Q

Why are system reloads necessary?

A
  • A high-availability banking system may only be reloaded once a year, or even less frequently, to refresh the software levels
  • Outside influences may often be the cause of Initial Program Load (IPLs), such as the need to test and maintain the power systems in the machine room
  • Sometimes badly behaved software uses up system resources that can only be replenished by an IPL
66
Q

What are the three types of reloads and how do they differ?

A
  • Cold start: An IPL (Initial Program Load) that loads the PLPA (Pageable Link Pack Area) and clears the VIO (Virtual I/O) data set pages
  • Quick start: An IPL that does not reload the PLPA, but clears the VIO data set pages
  • Warm start: An IPL that does not reload the PLPA, and preserved journaled VIO data sets

COM3310 (6 decks)

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