The information in this article applies to:
- Microsoft SQL Server version 4.2 for OS/2
SUMMARY
Microsoft SQL Server for OS/2 can be installed on several different
network operating systems and on several versions of OS/2. However,
the installation guide deals primarily with SQL Server configuration
parameters on LAN Manager networks. While each user's SQL Server setup
will be affected by their own application environment, there are some
general guidelines for the configuration of memory on networks other
than Microsoft LAN Manager and on OS/2 versions other than Microsoft
version 1.3.
MORE INFORMATION
It is very difficult with the OS/2 memory architecture for even the
author of a program to determine his program's consumption of physical
random access memory (RAM). This is because all OS/2 programs exist in
a 512-megabyte (MB) virtual address space, and there is not an
operating system application programming interface (API) that exists
for querying either the amount of total RAM in the computer, or the
amount of RAM consumed by a program. The only way to come close to
determining the physical memory consumption of a program is to keep a
record of all memory allocation requests. This article addresses ways
to maximize SQL Server's use of memory in two ways:
- Freeing up as much memory on the OS/2 system as can be made
available
- Guidelines for determining a safe level to set the SQL
Server memory parameter.
A safe level is one where SQL Server gets the most out of available
memory without causing OS/2 to get into a situation where it is
frequently swapping chunks of memory to the hard disk and thereby
causing a decrease in performance.
Freeing Available Memory
- Chapter 2 of the SQL Server "Installation Guide" gives several
pointers for freeing available memory. You should refer to this
for tips on how to disable read/write caching, turn off the MS-DOS
session, and to set OS/2 swapping options.
- The preferred file system for SQL Server on OS/2 is FAT (File
Allocation Table) instead of HPFS (High-Performance File System).
The two greatest advantages to FAT are that it allows SQL Server to
have access to more of the system's memory because FAT uses less
than HPFS; and in the event of disk problems, you can restart from
a MS-DOS disk and use any of the available MS-DOS utilities
available to attempt hard disk repairs in the event of physical
corruption on a device. Such utilities are much more widely
available for FAT than for HPFS.
All of the following recommendations assume the FAT file system is
being used. If you are using HPFS, or HPFS and FAT together, you
should subtract an additional 1 to 2 megabytes or RAM from these
recommendations.
- The standard installation of MS OS/2 version 1.3 will include
several device drivers for CD-ROM players that most SQL Server
users will not need to use. These lines can be commented out of the
CONFIG.SYS file.
This includes the following programs:
DENON.VSD
STDCDROM.VSD
CDROM.TSD
CDFS.IFS
Configuring SQL Server's Memory
- Each user's particular environment determines how much memory
they can configure SQL Server to use. If you configure SQL Server
to use too little, then you may see decreased client performance.
If you configure SQL Server to use too much, then you may
experience connectivity problems, or have the operating system go
into a thrashing mode as large parts of the network and SQL Server
software end up being swapped to disk.
A good way to determine if you have over-configured your SQL Server
memory is to monitor the size of the SWAPPER.DAT file. The
directory where this file is located is pointed to by the
SWAPPATH= entry in the OS/2 CONFIG.SYS file. If this file is
consistently getting larger than 11 or 12 MB, then you are probably
doing too much swapping and it could be affecting your performance.
- On Novell networks running the Netware requester for OS/2 version
1.3, with Microsoft or IBM OS/2 version 1.3, with 16 MB of RAM on
the computer, with the maximum available memory freed as described
above, and running FAT with no MS-DOS compatibility box enabled,
the suggested maximum amount of memory to configure SQL Server to
use is about 12 MB. If using the Microsoft's "SQL Server Network
Integration Kit for Novell Netware Networks," then about 11 MB is
the suggested maximum.
- On Banyan networks running VINES version 4.10 or later, with
Microsoft or IBM OS/2 version 1.3, with 16 MB of RAM on the
computer, with the maximum available memory freed as described
above, and running FAT with no MS-DOS compatibility box enabled,
the suggested maximum amount of memory to configure SQL Server to
use is about 12 MB. If using the Microsoft's "SQL Server Network
Integration Kit for Banyan VINES Networks," then about 11 MB is the
suggested maximum.
- Microsoft is currently supporting SQL Server version 4.2 on IBM
OS/2 version 2.0 on Novell and IBM LAN Server networks. At this
time, we are still testing on IBM OS/2 version 2.1, but have
clients who use it, and the memory configuration settings will
probably be similar to OS/2 version 2.0.
OS/2 version 2.0 can physically address more than 16 MB of physical
RAM. Microsoft SQL Server version 4.2 can address up to 64 MB of
memory when running on OS/2 version 2.0. However, Microsoft testing
indicates substantially more RAM may be required on OS/2 version
2.0 to provide the same level of performance as OS/2 1.3.
Furthermore, not all hardware platforms may be capable of using
greater than 16 MB under OS/2 2.0. Contact IBM and your hardware
vendor for more details.
For example, on a Novell network with the OS/2 version 2.0
requester, with 16 MB of RAM, and on a dedicated SQL Server
machine, the suggested maximum amount of memory to configure SQL
Server to use is about 8 MB. If this computer will also be used as
a user's workstation, you will need to configure SQL Server to use
less memory.
In a LAN Server environment with 16 MB of RAM on the computer, SQL
Server can be configured to use about 8 MB of memory. As more RAM
is added to the machine, SQL Server can be configured to use parts
of this, but in many cases best performance can be gained by also
leaving more RAM for the operating system. Experimentation will be
required to determine the most effective setting at various
physical memory capacity. The overall goal will be to increase SQL
Server's memory allocation up to the point where excessive OS/2
version 2.0 paging file growth occurs.
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