Ref: 11640074
Title: Tuning CIOSYS Parameters
Date: 4/20/90

Copyright 3Com Corporation, 1991.  All rights reserved.

Tune parameters for CIOSYS with the 3OPT program on the server.

1.  Start the 3OPT program in off-line mode.

    See "Starting 3OPT, Off-Line Access" in the 3+ Network Tuning
    Guide.

2.  In the 3OPT main menu, select the CIOSYS component and choose
    the CHANGE command.

    Three CIOSYS functions are displayed.  The functions that
    concern you are "Adjust CIOSYS Parameters" and "Adjust CIOSYS
    Buffer Pools."

3.  Select the "Adjust CIOSYS Parameters" function.

    When the parameters screen appears, adjust the parameters as
    appropriate.  See "'Adjust CIOSYS Parameters' Screen" later
    in this section.

    After you adjust the parameters, press [Ctrl] + A to save the
    parameters and exit the parameters screen.

4.  Select the "Adjust CIOSYS Buffer Pools" function.

    When the buffer pools screen appears, adjust the buffer pools
    as appropriate.  See "'Adjust CIOSYS Buffer Pools' Screen"
    later in this section.

    After you adjust the buffer pools, press [Ctrl] + A to save
    the adjustment and exit the buffer pools screen.

5.  Press [Ctrl] + A to return to the 3OPT main menu.

6.  Choose the Save command to save your changes so far.

    Remain in the 3OPT program to tune the 3+Share parameters.
    See "Tuning 3+Share Parameters" later in this manual.



"Adjust CIOSYS Parameters" Screen

Parameters on this screen include:

    Byte range locks
    File descriptors
    File handles
    Threads
    File sharing processes
    I/O request blocks

Byte range locks--If this setting is less than 150, 3+Backup will
run very slowly or not run at all.  A low setting will cause it
to wait for users to stop their activities and free up some byte
range locks.  In extreme cases, you may have a backup problem
even if no other users are on the system.  If you plan to run
3+Backup when other users are using the server, you may need to
set the Byte range locks setting higher.

To tune this parameter, start with the default setting and
increase it based on the number of users.  See "Tuning CIOSYS" in
the 3+ Network Tuning Guide for details.


File descriptors--This setting's value depends on the number of
active users and open files.  In most cases a setting of 200 is
sufficient to accommodate 20 users and still run 3+Backup.  See
"Tuning CIOSYS" in the 3+ Network Tuning Guide for details.

If the number of users and open files demands a higher setting,
consider running 3+Backup when network activity is low.


File handles--This setting's value depends on the number of
active users and open files.  In most cases a setting of 125 is
enough to accommodate 20 users and still run 3+Backup.  See
"Tuning CIOSYS" in the 3+ Network Tuning Guide for details.

If the number of users and open files demands a higher setting,
consider running 3+Backup during a period of lower activity on
the network.


Threads, File sharing processes, and I/O request blocks--Minimum
values for the these settings vary with the model server.

3Server/500 and 3Server386 servers require these minimum
settings:

    Threads = 10
    File sharing processes = 65
    I/O request blocks = 64

3Server3 and 3Server servers require these minimum settings:

    Threads = 7
    File sharing processes = 64
    I/O request blocks = 32

PC servers require these minimum settings:

    Threads = 4 to 6 depending on the server*
    File sharing processes = 64
    I/O request blocks = 32

* 80286-based PC servers require fewer threads; 80386-based PC
servers require more threads.

If Microsoft redirector errors 51, 53, or 55 occur, try a higher
setting for file sharing processes.  See "Tuning CIOSYS" in the
3+ Network Tuning Guide for details.



"Adjust CIOSYS Buffer Pools" Screen

The "Adjust CIOSYS buffer pools" screen contains a table that
assigns a cache buffer pool to every hard disk partition in the
server's base or expansion unit(s).  You can use this table to
create extra buffer pools for specific partitions on the server
and specify the number of buffers in each pool.

The important fields on this screen are

    Pool
    Num bufs
    CIOSYS data area, bytes left
    EMS left for CIOSYS buffers


Pool--This field is included in the table for every partition
listed.  It specifies a numbered pool of memory buffers that the
partition can use as a memory cache.

*   Assign the same numbered buffer pool to partitions of equal
    sector size and sectors per cluster.

*   Assign different numbered buffer pools to partitions of equal
    sector size and sectors per cluster.

If your server has an expansion unit with just one large
partition on the expansion drive, assign a separate pool to that
partition.

See "Tuning CIOSYS" in the 3+ Network Tuning Guide for details.


Num bufs--This field is included in the table for every partition
listed.  It specifies the number of memory buffers available from
each partition's buffer pool.

For 3+Backup version 1.5.2 the recommendations are

*   Specify a minimum of 34 buffers to a pool on a 3Server or
    3Server3.

*   Specify a minimum of 64 buffers to a pool on a 3Server386 or
    3Server/500.

See "Tuning CIOSYS" in the 3+ Network Tuning Guide for details.


CIOSYS Data Area bytes left--As you adjust the CIOSYS parameters
and Buffer pool settings, note the memory left free in the
"CIOSYS Data Area bytes left" information field on the right side
of your screen.  You should keep approximately 4 KB of memory
free.

See "Tuning CIOSYS" in the 3+ Network Tuning Guide for details.


EMS left for CIOSYS buffers--As you adjust the CIOSYS parameters
and Buffer pool settings, note the memory left free in the "EMS
left for CIOSYS" information field on the right side of your
screen.

*   Keep approximately 34 KB free for 3Server and 3Server3
    servers.

*   Keep approximately 64 KB free for 3Server386 and 3Server/500
    servers.

*   If your server has an expansion unit and only 1 MB of
    expanded memory (EMS), install an additional 1 MB of EMS.

You may be able to run 3+Backup with less than the recommended
EMS memory; however, reliability is better if the recommended EMS
memory is available and free.

See "Tuning CIOSYS" in the 3+ Network Tuning Guide for details.
