Integrated
File System
It is a
part of OS/400 that supports stream input/output and storage management.
It
comprises 10 file systems, each have its own logical structure and rules for
interacting with storage information.
- Support for storing the information
in stream file.
- A hierarchy directory
structure. (Objects maintain in Tree structure). Based on this access to
object is feasible by specifying the path through the directory.
- A common interface enables to
the user and applications to access the stream files, database file,
documents and other objects
Basic Concept:
- Directory:
A directory is a special object that is used to locate objects by names
that you specify. Each directory contain list of objects. The directory
branches have subordinate branches called as subdirectories.
When your job is started, the system looks in your user profile for the
name of your home directory. If it does not exist, the home directory is change
to root (/) directory.
Note: /home directory is sub directory under root (/) directory
- Link:
A link is a named connection between a directory and an object. A link
can be used as a path name or as part of path name.
There are two types of links, Hard Link and Symbolic Links
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Item
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Hard Link
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Symbolic Links
|
|
Name
resolution
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Faster. A
hard link have direct reference to object.
|
Slower.
It contains a path name to find the object.
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Object
existence
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Required.
An object must be exit.
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Optional.
It can refer to object that does not exit.
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|
Object
deletion
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Restricted.
It should be unlinked to delete an object.
|
Unrestricted.
The object can be deleted.
|
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Static
object (attributes do not change)
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Faster.
Name resolution is primary performance concern.
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Slower.
|
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Scope
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Restricted.
It cannot cross file system.
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Unrestricted.
It can cross file system.
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- Stream file:
It is randomly accessible sequence of bytes, with no further structure
imposed by the system.
IFS support for storing and operating information in the form of stream
files. The object type is *STMF
Stream file
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…………………………………………………………………………
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Database file (with Records) (Two records): It has predefined
subdivision.
Field 1 field
2 Field
N
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……………
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……………
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……………
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……………
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……………
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……………
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Note: There are other three concepts which are not covered here, namely Name
Continuity, Extended attributes and Scanning support.
Command To Copy To Stream File From Database
File:
CPYTOSTMF
FROMMBR(&FROMFLD) TOSTMF(&TOFLD)+
STMFOPT(*ADD)
STMFCODPAG(*PCASCII)
For file and directory the
authority need to be given as public to get the access to user:
CHGAUT
OBJ(&TOFLD) USER(*PUBLIC) DTAAUT(*RWX) +
OBJAUT(*ALL)
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