ITEM: H1190L

HOWTO: Configure HA/NFS (cabling, hardware requirements)

What are the configuration requirements for HA/NFS? How does HA/NFS


IBM Announcement Letter: 293-356
Dated:  7/13/93 

describes the HANFS Configuration recommendations as follows:

To further improve reliability, availability, performance and
capabilities of HANFS, IBM is taking the strategic steps
to introduce the SCSI Differential hardware subsystems.  IBM
will continue to support customers with IBM SCSI-SE
Increased Availability Subsystems. 

The following hardware cannot be ordered for an HANFS configuration:
o   SCSI Controller Passthrough Terminator Cable Feature 2915
o   SCSI-2 Passthrough Terminator Cable Feature 2914
o   SCSI-I 670 MB and 355 MB Disk Drives.

The following are no longer recommended for a HA/NFS configuration:  
o   9334-500 Expansion Unit
o   SCSI-1 SE Disk Adapters, feature 2835
o   SCSI-2 SE Disk Adapters, feature 2410
o   320MB Bridge Box 7204-320

The following are not supported for an HANFS configuration:
o 9334-500 Expansion Unit with
  - 670 MB Disk Drive, feature \#9247, \#2510
  - 1 GB Disk Drive
  - 2.0 GB Disk Drive, feature \#2580, \#2583
  - 2.4 GB Disk Drive, feature \#2590, \#2593
  - All future IBM SCSI SE drives
o Bridge Box
  - 1 GB Disk Drive 7203-2320, 7203-2312, 7204-001
  - All future IBM SCSI SE drives

The following are recommended for an HANFS configuration:
o SCSI-2 Differential Subsystem
  - SCSI-2 Differential High Performance I/O controller,
    feature 2420
  - 9334-501 with 1 GB IBM SCSI Controller Differential
    files, feature \#9245, \#2565 2 GB IBM SCSI
    Differential files, feature \#2585, \#2588
  - 9334-011 with 1 GB IBM SCSI Controller Differential
    files, feature \#9245, \#2565 2 GB IBM SCSI
    Differential files, feature \#2585, \#2588
  - 7135-010 IBM RAIDiant Array
  - 7135-110 IBM RAIDiant Array
o IBM 9333 High-Performance Disk Drive Subsystem -- supported  models are:
  - 9333 Model 500
  - 9333 Model 501 
  - 9333 Model 010
  - 9333 Model 011
The following POWERstation/POWERserver units are supported for HANFS:
320       530
320H      530H
340       550
350       560
360       570
370       580
355       930
365       950
375       970
365       980
520       970B
520H      980B                            

NFS is a distributed file system that allows users to access files and
directories located on a remote system as if they were local.  HANFS
is an IBM extension to NFS that utilizes shared SCSI string technology
to increase the availability of data provided by a NFS server in a
TCP/IP network.  It's configuration consists of shared SCSI string(s)
connected to 2 RISC System/6000s.  The file systems/directories
exported by the NFS Server are located in external volume group(s) on
the shared SCSI string(s).  HANFS can survive certain types of planned
and unplanned hardware and/or software outages.

When a primary server in a HANFS pair fails, the backup system will
takeover the shared SCSI string(s) and disk(s) owned by the primary
NFS server and imitate the primary NFS server on the network.
Takeover is transparent to NFS clients on the network, taking anywhere
from 30-300 seconds depending on the number of shared SCSI strings and
SCSI disks the primary server owns.  The NFS locks held by the primary
NFS server's clients are re-claimed on the backup system during a
takeover.  NFS client requests are merely delayed during takeover.
HANFS does not need any additional coding to handle NFS locking. The lockd
has been changed to handle the HANFS configuration.                    

There are 2 possible configurations for HANFS.  In the first
configuration, one of the 2 systems is an active NFS server.  The
other system is a backup system, and is only an NFS server when the
primary NFS server fails.  In the second configuration, both systems
are active NFS servers, and each system acts as a backup for the other

Support Line: HOWTO: Configure HA/NFS (cabling, hardware requirements) ITEM: H1190L
Dated: March 1994 Category: N/A
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