INF107 - Minicomputer Operations
Class Four
I.Chapter 7 – Storage Management
A.Types of Storage
1.Main Storage (RAM)
2.Auxiliary Storage (Disk, etc.)
B.Concept of “Single Level Storage”
1.Main and auxiliary storage are managed in the same way (they are part of the same address space)
2.Virtual memory technique
a)Gives the system the ability to run more programs than what the main storage will support
b)Single Level Storage is different than the “swap files” of Windows or the “page pools” of mainframes
C.Auxiliary Storage management
1.OS/400 can manage the disk storage for you
a)Let it do this unless you are a very sophisticated user!
2.OS/400 spreads objects across multiple disk drives
a)Advantages
(1)Improves random access retrieval
(2)Gives optimal disk arm utilization
(3)Simplifies storage management
b)Disadvantages
(1)If a disk drive fails, all objects in the storage pool will be compromised unless data protection is used.
3.Methods of data protection
a)RAID (Redundant Arrays of Inexpensive Disk) is a set of strategies to protect your data from loss!
(1)Raid-1 (Mirroring)
(a)makes two identical copies of your data
(b)uses the most disk, but is the most reliable
(2)Raid-5
(a)Writes redundant data across the disk drives in a way so that the data can be reconstructed if one drive is lost
(b)Uses less disk, but is vulnerable to two simultaneous drive failures
b)Using RAID techniques, the AS/400 system can recover from disk failures without being brought down / up
(1)One of the ways to improve availability
4.Auxiliary storage management commands
a)RCLSTG – Reclaim Storage
(1)Performs cleanup (garbage collection) on the system
(2)Requires a dedicated system
b)RGZPFM – Reorganize Physical File Member
(1)Compresses / optimizes / defragments files
(2)Requires exclusive access to a file (not to the entire system)
D.Main Storage management
1.Main storage can be subdivided into multiple “pools”
a)A pool is a logical separation of main storage
b)A pool is specified in the subsystem definition
c)You use separate storage pools to segregate jobs with different operating / memory usage characteristics
(1)Paging characteristics
(a)*PURGE = *NO
(i)Demand page (bring in pages only when required)
(ii)Best for batch & spool jobs
(b)*PURGE = *YES
(i)Swap entire job in / out of memory
(ii)Best for interactive jobs
(2)Segregate Batch, Interactive, & Spool tasks into separate pools
(a)Each type of task has different memory use characteristics.
d)Special storage pools
(1)*MACHINE
(a)Always pool #1
(b)Contains the operating system
(c)If the machine pool is not big enough, the entire machine slows down
(2)*BASE
(a)Always pool #2
(b)Has main storage shared across the entire system
(c)Can have multiple subsystems running in it
(3)WRKSHRPOOL command shows storage pools that can be shared across subsystems.
e)You can define private pools for a subsystem as part of the subsystem description
2.Each pool (other than the machine pool) has an “Activity Level”
a)This is the number of jobs that can be in memory at once!
b)For pools with *PURGE = *NO (Batch), make this the number of the maximum number of jobs that could run at once in the pool.
c)For pools with PURGE = *YES (Interactive), calculate this value from the “Work Management” reference from IBM (on web site)
3.The command “WRKSYSSTS” is the key storage management command
a)Allows you to view all active storage pools and change their size on the fly
E.Hierarchical Storage Management
1.Option to have infrequently used data moved automatically from disk to tape
II.Chapter 8 – System Security
A.System security is like insurance, you don’t need it until you need it!
1.The AS/400 has been given a C2 rating (Very high security!) by the NSA for both the operating system and the database. This is the first time that NSA has certified a machine’s operating system and database at the same time!
B.You have to know what you are doing in order to have tight security
1.Most security breaches (on any system) come from situations where the security administrator does not really understand what they are doing!
C.Security should be like the layers of the skin of an onion
1.You should have to go through a lot of layers before you get to the core!
2.Common security layers
a)Physical security
(1)If you can’t touch a computer (or communicate with it), you can’t get at it
(a)This is why computers are usually in locked rooms!
(2)If you can touch it, you have a head start in getting into it
(a)Firewall device controls who gets to communicate (logically touch) with the system
D.Operating system security
1.Ability to set overall security strategy using system value QSECURITY
a)Level 10 – Userid only
(1)No password check
(2)Relies on physical security
(3)NOT RECOMMENDED (IBM no longer supports it)
b)Level 20 – Password security
(1)Requires a userid / password
(2)If you get to a signed on client, you have complete access to the system!
(3)NOT RECOMMENDED
c)Level 30 – Resource security
(1)Requires a userid / password
(2)Userid must be authorized to objects in order to use the objects
(a)By object owner OR security officer
(3)Most widely used security level
(4)MINIMUM RECOMMENDED LEVEL OF SECURITY
d)Level 40 & 50- System Interface Security
(1)Requires a userid / password
(2)Userid must be authorized to objects in order to use the objects
(a)By object owner AND security officer
2.User Profile
a)Uniquely identifies you as a user of the system (Level 20 & above)
b)Contains your password
c)Identifies you & your security characteristics to the operating system
(1)User class gives the system a rough idea who you are (User, system operator, programmer, security administrator, security officer)!
(a)System uses user class to do an initial setup of security characteristics
(2)Group profiles allow multiple users to share the same object authorizations
3.Object authority
a)Who can do what to an object?
(1)Read, write, update, delete
4.Authority lists
a)Allow common object authority for multiple objects
III.Chapter 9 – Backup and Recovery
A.System backup is insurance, you don’t need it until you need it!
B.The easiest way to get fired from a data processing job is to get caught with a faulty backup and recovery scheme!
1.A disk drive goes bad … no disk data protection … faulty backup … company is “out of business” … “YOU’RE FIRED!!!”
C.Disaster Recovery Plan
A written plan, which must be tested, which documents the procedures to be followed if the company’s computing facilities are unusable due to fire, flood, or other emergency.
D.Save to disk
1.Option to “Save while active”
a)High availability option
2.Danger if you save to disk & disk goes bad before you copy data off
E.Save to tape
1.Tape is most practical alternative for backing up the system
2.AS/400 supports many different tape formats
3.The “INZTAP” command causes a tape to be initialized (and optionally formatted)
F.Save commands
1.SAVSYS – Saves operating system (Including security and device configurations)
2.SAVLIB LIB(*NONSYS) – Saves all user & IBM supplied libraries
a)SAVLIB – Saves an individual library
b)SAVOBJ – Saves an individual object
c)SAVCHGOBJ – Saves objects which have “changed”
3.SAVDLO – Saves system folders
4.SAV – Saves contents of the Integrated File System
G.Restore commands
1.“IPL from Tape”– Restores operating system
a)RSTCFG – restores configuration
b)RSTUSRPRF – restores user profiles
c)RSTAUT – restores object authorizations
2.RSTLIB LIB(*All) – restores all user & IBM supplied libraries
a)RSTLIB – restores an individual library
b)RSTOBJ – restores an individual object
3.RSTDLO – restores system folders
4.RST – restores contents of the Integrated File System
H.Backup strategies
1.This can be a class in itself!
2.Tied to the amount of time that you have to back the system up (Backup Window) and how dynamic your system is
3.For more information, see the AS/400 Backup and Recovery Guide (SC41-5304) at
IV.Test 1 Review
1.Review Chapters 1 to 9
2.Question and answer period before test
3.Test will be:
a)“Open System, Closed Book, Closed Notes, Closed Message / E-mail, Closed Web Site, Closed Everything Else”
b)Material from
(1)Lectures / lecture notes
(2)Labs
(3)Assigned reading in textbook
c)Questions will include: multiple choice, matching, & fill in the blanks
V.Lab
A.There are no materials to hand in with this lab. If you do not fully do this lab, you will feel pain in the test!
B.Sign on to the system, using your user profile and password
C.DO NOT CHANGE ANY EXISTING VALUE IN THE SYSTEM!!
1.If you change one accidentally, contact the instructor AT ONCE!!
D.Use the command “WRKSYSVAL *STG” to look at the current values for storage management.
E.Use the command “WRKSYSVAL *SEC” to look at the current values for security
F.Use the command “WRKSYSVAL *SYSCTL” to look at system control values
G.Use the command WRKSYSSTS to look at:
1.how the main storage pools are organized
2.how much total available disk is available on the system
3.Press the F24 key (Shift F12) to change the function keys displayed on the bottom of the screen
4.Press the F14 key (Shift F2) to run the WRKSBS command.
5.Look at the subsystem descriptions to see how the main storage pools are specified at the subsystem level
6.Use the F12 key to go back to the WRKSYSSTS screen
7.Press the F16 key (Shift f4) to run the WRKDSKSTS command.
8.Look at the disk units which are configured on the system.
9.Press the F24 key until F11=Display Storage Use is shown
10.Press the F11 Key. Note that the type of storage protection which is used on the disk drives.
11.Press the F3 key until you get back to the main menu.
H.Use the command WRKSHRPOOL to look at:
1.Main storage pools which are shared between subsystems
I.Sign off the system and end the client access program prior to leaving the lab!
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