Ref: 17350006
Title: Over-the-Network Backup Fails with Internal Error 5 RC=7
date: 12/27/90

Copyright 3Com Corporation, 1991.  All rights reserved.

When performing over-the-network backups (either full, incremental, or
appended), the tape is prepared or erased, but when data transfer commences,
the backup fails.  BACK_LOG reports Internal Error 5 RC=7.  However,
backups from the server to its local tape drive complete successfully.

The problem is caused by improper tuning.  It was replicated at 3Com in this
environment:  3Server386 with 3+Share 1.3.1, 3+Backup 1.3.1 used as the
source of data; also on a 3Server with 3+Share 1.3.1, 3+Backup 1.3.1, 3+Name,
and Locator used as destination for Backup.  The 3+Share parameters were
incorrectly set as follows:

.LT
    Message Buffer Size     4144
    Message Buffers         10
    Concurrent Requests     6
    Receive Buffers         20
    Transmit Buffers        21
.EL

Adjusting Concurrent Requests to 9, Receive Buffers to 30, and Transmit
Buffers to 35 solved the problem.  New buffer values were determined
by (4144/1500) * Message Buffers.  This calculates to (3 * 10) or 30
Receive Buffers.  3Com recommends setting Transmit Buffers equal to or
slightly higher than Receive Buffers.  The number of Concurrent Requests was
calculated as (Message Buffers - 1).

After the parameters were adjusted and the server was reset, all backups
completed successfully.

