Software Vault: The Gold Collection/Software Vault - The Gold Collection (American Databankers) (1993).ISO/cdr28/perf.zip/PERFOR.TXT

Text File | 1993-03-03 | 20KB | 356 lines

TECHNICAL BULLETIN                                                        PERFORM
LANtastic Performance Issues


The following information is based on in-house testing of LANtastic.  If you are
not a registered LANtastic owner, your questions should be directed to our
technical sales staff at [phone].  Any questions or comments on this
bulletin may be forwarded by FAX [phone] or mailed to: Artisoft Inc., 691
East River Road, Tucson, AZ., 85704, ATTN: Technical Support.

GENERAL HINTS AND TIPS
INCREASING PERFORMANCE OF LANTASTIC NETWORKS


"What can I do to speed up my LAN?" A very common question, and one to which
there is unfortunately, no cut and dried answer. Network performance depends on
many things.  Getting the best performance out of your particular installation
may require a little experimentation. This bulletin presents a discussion of some
of the major factors that affect performance, and a few general suggestions for
improvement.

Choosing your Hardware

When you're choosing the hardware for your LAN, keep in mind that the things that
make a fast computer are also the basic ingredients of a fast network. A fast
processor, fast memory and a fast disk drive all help to provide better network
speed. For best performance, you should choose fast, well balanced components.
The two biggest factors are CPU speed and hard disk speed.

It's fairly easy to find fast computers and fast disk drives out there in the
marketplace, but for the best results make sure that the components you buy are
well matched. If you install a high performance disk drive in a 4.77 Mhz XT, your
network will be slow because the computer's CPU won't be able to move data around
fast enough to keep up with the drive, let alone the rest of the network.
Similarly, if you install an old 20mb MFM drive in your 386-33, the fast
processor will spend a lot of time waiting around for the old drive, as will the
rest of your network users.

The transmission speed of the adapter cards you choose will also make a
difference. With reasonably fast machines, upgrading from a LANtastic 2mbps
adapter to a new Artisoft Ethernet adapter can approximately double the
throughput of the network. Again, balance is vital. If you have a slow processor,
switching to Ethernet may not make much difference -- the 2mbps adapter has a
coprocessor that handles all the low level NetBIOS processing, whereas the
Ethernet adapter relies on the computer to handle everything.

Optimizing Software Performance

Now that we've dealt with hardware selection; let's see what can be done to
improve the performance of existing installations. First, let's tie down what we
mean by the "speed" of the LAN. There are really two things at issue here, the
physical transmission speed of the hardware, and the effective throughput, or how
fast data gets from one place to another on the LAN. Assuming for now that the
hardware is fixed and immutable, here are some suggestions for getting the best
throughput with your particular application.

Optimizing Network Configuration

There are two major configurations of the network that will greatly benefit
overall network performance.

The first is simply using LANtastic's ability to have more than one server on the
network.  Splitting up network tasks so that different programs are run on
separate servers will decrease the load on each individual server, this will
improve the servers response (and on a non dedicated server improve the
performance of the computer for the person sitting at the keyboard).

The next is setting up a dedicated server (while LANtastic is a Peer to Peer
network - Artisoft considers a dedicated server to be only a special case of peer
to peer networking). A dedicated server can be specifically tuned to optimize the
performance of the Network portion of the computer at the detriment of the
Workstation (keyboard) portion of the computer.

This is done by using the RUN_BURST command line switch (on AILANBIO with
versions of LANtastic prior to 4.1, on both AILANBIO and SERVER with version 4.1
and greater).

This switch controls the amount of time that the program (either netbios or
server) devotes to processing network tasks.  The higher the value the longer
amount of time allocated.  Since both REDIR and SERVER  release control if there
are no tasks waiting neither switch will conflict with the other.  Setting these
switches to the max 254 will give optimum performance for a dedicated server.

In a dedicated server, memory no longer is a major consideration. Large sizes for
the servers caching and buffers should be experimented with.  (See server
buffering below.)

Another command that is useful for a dedicated server is the ALONE command
included with v4.0 and higher.  When the server program is used to access a
resource on the server, it first swaps out all the DOS stacks and control memory.
It does this so a foreground task can coexist with the server running in the
background. On a dedicated server Alone tells the server that there will NEVER be
a program running on this machine in the foreground using DOS and so server saves
time by NOT swapping into and out of DOS.  This means that you cannot run a TSR
(Terminate and Stay Resident program)  on this dedicated server that will use dos
calls.

General Improvements

FASTOPEN

Running the DOS FASTOPEN command will improve network speed considerably(except
with MSDOS 5.0 because of a reported problem in this version's FASTOPEN).
FASTOPEN stores the location on the hard disk of each previously opened file to
make repeated access to this file much faster.



SEEK CACHE

LANtastic 4.1 contains a new cache built into the server program, SEEK CACHE.
SEEK CACHE caches each users position within open random access files. Typically
a seek cache will significantly affect performance of random access file
operations if:

     1> Files being accessed are relatively large.
     2> The files are kept open and accessed frequently.

The optimum size for the  SEEK CACHE is the SIZE of database files/cluster size
(typically 4096)* 32 + the Number of files *32.


RESOURCE CACHE

When a user on LANtastic accesses a resource, LANtastic has to check the
resources Access Control List (ACL) to see what permissions the user has.  This
requires loading the resource information from the hard disk and checking it.  To
improve performance with LANtastic NOS 4.1 resource caching can be enabled on a
server.  This means that as each resource (disk or printer) is accessed it's
access information  is stored in a permanent cache in the server.  There should
be one cache specified for each commonly used resource. If a server has several
resources, but only a few are normally accessed, the cache number can be set to
the number of commonly used resources +1.  The caches are flushed and used on a
least frequently accessed algorithm so system performance will be only slightly
affected.


INDIRECT FILE ACL's

Indirect files will greatly effect network performance, with LANtastic NOS 3.0x
eliminate the I from each disk resources Access Control List.  With NOS 4.xx the
I ACL has already been eliminated. With the I ACL in place each time a file is
opened the NOS checks to see if the file is an indirect file.  If you are not
using indirect files eliminating this ACL will save time when a file is opened.

SERVER AUDITING

Indirectly, server auditing can also have a great effect on network performance.
If auditing is enabled and the audit files are not cleared on a regular basis
this file can grow very large.  This by itself is not a problem; but since
auditing requires that an entry be made to this file every time an audited
function is used, the time spent seeking to the end of this file will increase as
the file size increases.

SEND SERVER ID

You can reduce the load on heavily used networks by disabling the Send Server ID
selection in NET_MGR, Server Startup Parameters. With this selection enabled the
server sends out a message once every retry period (55ms x retry_period setting),
this message is just that the machine is a server and available.  If your system
is using batch files this message is not needed.  If the server name is known, it
can be logged into even if the server is NOT sending out it's ID.

DISK CACHING

Adding a disk cache to the server also helps performance in almost all
situations. Disk caching programs work by storing frequently requested
information in memory. This reduces the number of physical accesses to the disk.
Since accessing memory is almost always faster than accessing the disk drive,
caching can greatly improve the disk performance of your network.

The LANtastic disk caching program; LANcache, is specifically designed to work
with LANtastic networks. It caches disk writes as well as disk reads and when it
actually does have to write to the disk, it does so as a background operation so
that CPU operations can continue.

Choosing the Best Buffer Settings

Beyond these general changes, getting the best performance out of your specific
application is a matter of fine tuning several parameters. LANtastic has four
sets of buffers, each of which can affect performance in specific situations.

REDIR Buffers

It takes the network about the same amount of time to send 1 byte of data as it
does to send 256 bytes of data. Every packet sent over the network takes time to
construct and time to process. Given this, it makes sense to include as much data
as possible in each packet -- it keeps the network overhead impact to a minimum
and reduces network traffic. The REDIR program accomplishes this by buffering
network requests at each machine. Here's an example of REDIR's buffering in
action:

     You are creating a file of customer names on the server and adding data to
     it. You type in the names one at a time and your program writes the names to
     the data file one at a time. Rather than issue a network send for each name,
     the data gets stored in the local REDIR buffer until you close the file or
     fill the buffer. At that point, REDIR issues a single request to send the
     entire buffer.

REDIR buffers read requests similarly. If you request an amount of data smaller
than the REDIR buffer, REDIR requests one buffer full of data from the server.
Then, if you request the next sequential piece of data, REDIR can supply it to
your program without even making a network request.


REDIR buffers are only used for small (small means smaller than the REDIR buffer
size) sequential reads or writes to files that are NOT opened in the sharable
mode. If you read or write blocks of data larger than the REDIR buffer, the
network software bypasses it and moves data directly from the applications buffer
directly to the NetBIOS. The ideal REDIR buffer size then, would be about the
average size of the packets that your network typically sends and receives. You
can set the size of the REDIR buffers with the SIZE= command line switch.

The number of REDIR buffers can also affect the performance of many applications.
If you allocate multiple REDIR buffers using the BUFFERS= command line switch,
the network tries to associate each file opened in the non sharable mode. Network
printers are handled just like other files. Ideally, you should have a buffer
available for each open non sharable network file. If you have more files than
available buffers, the network flushes the least recently used buffer and assigns
into the new request.

WordPerfect is a good example of a program that is affected by the number of
buffers. If you have only one buffer allocated, printing can be very slow because
WP has to read the document and send data to the printer with the same buffer.
The buffer gets continually filled and flushed, back and forth, with printer data
and document data. In this situation, allocating just one more buffer allows WP
to use one buffer for document reading and another for printing.

Server Buffers and Tasks

A server buffer is at the other end of a REDIR buffer. When, for example, a
workstation makes a read request, the server reads one server buffer full of
data, beginning with the information requested. If the workstation then asks for
the next piece of the same information, the server can get it from the buffer
instead of physically reading the hard disk.

The server buffer size can be changed from the Server Startup Parameters option
in the NET_MGR program. Be aware that bigger isn't necessarily better -- as with
REDIR buffers, the optimal size is somewhere around the average size of the
packets that will be transferred across the network by your application. One
server buffer of whatever size you select is allocated for each network task.
Large network buffers will greatly effect the speed when moving large amounts of
sequential data across the network. Loading programs, using a word processor, and
using a cad program are all examples of the type of applications and use that can
benefit from large server buffers.

When a workstation submits a request to a server, the server will work on the
request until the task is finished, or the timeslice allocated to the server is
over. If the server is set up with only one network task, instead of switching,
the server will run the request to completion and other incoming tasks will be
queued up behind it. If server tasks are higher, the server can process several
tasks in one active period. One task can actually be buffered in the server while
another in being processed.If you're a using network adapter with a coprocessor, like our Enhanced 2mbps
adapter, increasing the number of network tasks (with the Server Startup
Parameters option of NET_MGR) will give you a big performance boost. While the
coprocessor is busy working on one task, the server's CPU can work on another.
This advantage is multiplied if you have more than one coprocessor equipped
adapter in a server. In fact, with three or four 2mbps boards in a dedicated
server and a corresponding number of network tasks, you can achieve a continuous
throughput comparable to that of an Ethernet network with an equal number of
stations. As a plus, you've got built-in redundancy -- the workstations connected
to each adapter will function as separate networks. If one segment fails because
of cabling or adapter problems, the rest will still operate.

SERVER REQUEST SIZE

With NOS 4.xx a new parameter has been added to change the size of the server
request buffer. The REQUEST_SIZE= is set to 14 bytes by default. If a request
from a workstation is smaller than this buffer, the server will be able to act
directly on this request. If the request is larger than the request buffer, it
must be buffered by the SERVERS initial send buffer, and system overhead is
increased.  The value of 14 is chosen specifically for LANtastic.  This 14 byte
buffer is large enough to tell the server what type of operation and how many
bytes the total operation will take.

There are some natural breaks in the size of this buffer.  The default will
handle only the very smallest network tasks, lock, unlock, closing a file, etc.
At 60-70 bytes most network activity except reads and writes are processed
without additional buffering, and from 600-2048 small reads and writes are
processed without additional server buffering.  This parameter should NOT be set
larger than the AILANBIO Initial Send Buffer. One request buffer is allocated for
each user in MAX USERS (LOGINS= command line switch).

LOCK HOLD TIME

Artisoft has discovered that setting the lock hold time higher than 0 with
LANtastic v4.1 can have an adverse effect on the time required to open a file.
This parameter should be used cautiously. If your use of the network entails
opening and closing a large number of files, then this parameter should be set to
a low value.  If your use of the network involved accessing a large common data
file, then increasing the value of this parameter will help performance.

NetBIOS and Adapter Card Memory

With LANtastic v4.xx ethernet cards, you can increase the netbios packet size.
This can have an effect on the system speed when loading programs and performing
large sequential reads and writes.  Increasing the PACKET_SIZE beyond 1500 bytes
moves the network out of IEEE802.3 standards and may cause problems if you are
using third party IEEE devices like routers or bridges.

With our AE-2 card, there's an easy way to get a performance boost on heavily
loaded networks. You can upgrade the adapter from its default 16K configuration
to a full 64K of RAM. It is fairly easy to tell when this upgrade is needed.
Start the network; if after 10 minutes of use lancheck shows network resource
exhuasts, increasing the memory on the adapter will help network performance.

Effects of Changing Buffer Sizes

Keep in mind that on systems with only two or three stations, changing the buffer
configuration may not have any measurable impact on speed. In any case,
increasing the size and number of REDIR and SERVER buffers uses memory and can
slow down programs running on the server. If your application performance is
critical, consider setting up a dedicated server for your most used application
programs and printers.

Running Applications on the Server

To get the best performance out of your network when you run applications on a
server, you should always use the server as though it was a remote workstation:
log in and access the application through network drives. Using the server
locally, without logging in, places you in contention with the rest of the users
and network performance can suffer. If you log in, the server will schedule you
along with the rest of the network users and everyone will get good performance.
This does NOT mean that you should issue NET USE commands that use a drive over
itself, IE NET USE C: \\SERVER\C-DRIVE.  This can cause problems.  It is better
to create a common network redirection ie NET USE G: \\SERVER\C-DRIVE and have
ALL workstations (even the server) access the program off of G:.

Increasing Print Speed

One of the slowest things about printing to a network printer is spooling to the
hard disk. With LANtastic NOS 3.0 and above you can easily increase the print
spooling speed by spooling to a RAM disk. To change the spooler's location, use
the Change Spool Location option of NET_MGR's Queue Maintenance function.  You
must be sure that the ramdisk is large enough to hold both the largest file
printed and all print requests that may be submitted at one time.  The spooler
will exit with an error if there is not enough space available on this drive.

PRINTER BUFFERS

As with REDIR and server buffers, increasing the size of your printer buffers can
improve printing speed. If your server has more than one printer attached,
increasing the number of printer tasks will allow it to print to more than one
printer simultaneously. Artisoft has determined through testing that with some
applications running on the server optimum printing is achieved with printer
tasks set to 1 no matter how many printers are attached to the server. Notably
these applications are Windows 3.x, Clipper 5.0, and Lotus products. If you
notice slow printing when running one of these programs on a print server, you
can increase print speed by setting printer tasks to 1 and setting cps in the
printer resource to 9600.

ARTISOFT, Inc. makes no warranties as to the completeness or accuracy of this
document.  LANtastic is a registered trademark of ARTISOFT, Inc.  Brand names and
product names are trademarks or registered trademarks of their respective
companies. Network Performance Issues