Integrated File System Introduction

 

Use QFileSvr.400 through the integrated file system interface

The QFileSvr.400 file system can be accessed through the integrated file system interface using either the OS/400 file server or the integrated file system commands, user displays, and APIs. In using the integrated file system interfaces, be aware of the following considerations and limitations.

The characteristics of the QFileSvr.400 file system are determined by the characteristics of the file system being accessed on the target server.

Case-sensitivity in the OS/400 file server file system

For a first-level directory, which actually represents the "root" (/) directory of the target system, the QFileSvr.400 file system preserves the same uppercase and lowercase form in which object names are entered. However, no distinction is made between uppercase and lowercase when QFileSvr.400 searches for names.

For all other directories, case-sensitivity is dependent on the specific file system being accessed. QFileSvr.400 preserves the same uppercase and lowercase form in which object names are entered when file requests are sent to the OS/400 file server.

Path names in the OS/400 file server file system

• Path names have the following form:

     /QFileSvr.400/RemoteLocationName/Directory/Directory . . . /Object
  

  The first-level directory (that is, RemoteLocationName in the example shown above) represents both of the following:

  • The name of the target server that will be used to establish a communications connection. The target server name can be either of the following:
    • A TCP/IP host name (for example, beowulf.newyork.corp.com)
    • An SNA LU 6.2 name (for example. appn.newyork).
  • The "root" (/) directory of the target server

  Therefore, when a first-level directory is created using an integrated file system interface, any specified attributes are ignored.

  First-level directories are not persistent across IPLs. That is, the first-level directories must be created again after each IPL.

• Each component of the path name can be up to 255 characters long. The full path name can be up to 16 megabytes long.

  The file system in which the object resides may restrict the component length and path name length to less than the maximum allowed by QFileSvr.400.

• There is no limit to the depth of the directory hierarchy, other than program and system limits and any limits imposed by the file system being accessed.
• The characters in names are converted to UCS2 Level 1 form when the names are stored (see Name continuity).

Communications in the OS/400 file server file system

• TCP connections with the file server on a target server can be established only if the QSERVER subsystem on the target server is active.
• SNA LU 6.2 connections are attempted only if there is a locally controlled session that is not in use (for example, a session specifically established for use by the LU 6.2 connection). When establishing LU 6.2 connections, the QFileSvr.400 file system uses a mode of BLANK. On the target system, a job named QPWFSERV is submitted to the QSERVER subsystem. The user profile of this job is defined by the communications entry for the BLANK mode. For more information about LU 6.2 communications, see the publication APPC Programming .
• File server requests that use TCP as the communications protocol are performed within the context of the job that is issuing the request. File server requests that use SNA as the communications protocol are performed by the OS/400 system job Q400FILSVR.
• If a connection is not already established with the target server, the QFileSvr.400 file system assumes that the first-level directory represents a TCP/IP host name. The QFileSvr.400 file system goes through the following steps to establish a connection with the target server:
  1. Resolve the remote location name to an IP address.
  2. Connect to the host server's server mapper on well-known port 449 using the resolved IP address. Then send a query to the server mapper for the service name "as-file." One of the following occurs as result of the query:
     • If "as-file" is in the service table on the target server, the server mapper returns the port on which the OS/400 file server daemon is listening.
     • If the server mapper is not active on the target server, the default port number for "as-file" (8473) is used.

     The QFileSvr.400 file system then tries to establish a TCP connection with the OS/400 file server daemon on the target server. When the connection is established, QFileSvr.400 exchanges requests and replies with the file server. Within the QSERVER subsystem, the QPWFSERVSO prestart requests take control of the connection. Each prestart job runs under its own user profile.

  3. If the remote location name is not resolved to an IP address, the first-level directory is assumed to be an SNA LU 6.2 name. Therefore, an attempt is made to establish an APPC connection with the OS/400 file server.
• The QFileSvr.400 file system periodically (every 2 hours) checks to determine if there are any connections that are not being used (for example, no opened files associated with the connection) and those connections had no activity during a 2-hour period. If such a connection is found, the connection is ended.
• The QFileSvr.400 file system cannot detect loops. The following path name is an example of a loop:

     /QFileSvr.400/Remote2/QFileSvr.400/Remote1/QFileSvr.400/Remote2/...
  

  where Remote1 is the local system. When the path name that contains a loop is specified, the QFileSvr.400 file system returns an error after a brief period of time. The error indicates that a time-out has occurred.

  The QFileSvr.400 file system will use an existing free session when communicating over SNA. It is necessary to start the mode and establish a session for the QFileSvr.400 to successfully connect to the remote communications system.

Security and object authority in the OS/400 file server file system

If both of the systems have Kerberos configured, and the user has authenticated to Kerberos, then Kerberos may be used to authenticate a file system that resides on a target iSeries server. If the Kerberos authentication fails, then the user ID and password may be used to verify access.

If the ticket-granting ticket or the server ticket expires after the target server has verified your access, the expiration will not be effective until the connection to the target server has ended. For more information on Kerberos, see the Network authentication service topic in the iSeries Information Center.

• To access a file system that resides on a target iSeries server, have a user ID and password on the target server that matches the user ID and password on the local server if Kerberos is not used to authenticate.

  If your password on the local or target server is changed after the target server has verified your access, then the change is not reflected until the connection to the target server has ended. However, there is no delay if your user profile on the local server is deleted and another user profile is created with the same user ID. In this case, the QFileSvr.400 file system verifies that you have access to the target server.

• Object authority is based on the user profile that resides on the target server. That is, you are allowed to access an object in the file system on the target server only if your user profile on the target server has the proper authority to the object.

Links in the OS/400 file server file system

The QFileSvr.400 file system supports only one link to an object. Symbolic links cannot be created or stored in QFileSvr.400. However, files in QFileSvr.400 can be accessed by using a symbolic link from the "root" (/), QOpenSys, or user-defined file systems.

See Link for a description of links.

Use integrated file system commands and displays in the OS/400 file server file system

The commands listed in Perform operations using CL commands can operate on the QFileSvr.400 file system, except for the following:

ADDLNK

APYJRNCHG

CHGAUT

CHGOWN

DSPAUT

ENDJRN

RST

SAV

SNDJRNE

STRJRN

WRKOBJOWN

WRKOBJPGP

The same restrictions apply to the user displays described in Perform operations using iSeries menus and displays.

Use integrated file system APIs in the OS/400 file server file system

The C language functions listed in Perform operations using APIs can operate on the QFileSvr.400 file system, except for the following:

chown()

fchown()

givedescriptor()

link()

QjoEndJournal()

QjoRetrieveJournalInformation()

QJORJIDI()

QJOSJRNE

QjoStartJournal

Qp0lGetPathFromFileID()

symlink()

takedescriptor()

---

[ Top of Page | Previous Page | Next Page | Table of Contents | Index ]