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CD SHARE CD ROM NETWORK SHARING SOFTWARE Version 1.1 User's Manual Digital Solutions Pty. Ltd. P.O. Box 178 Margate QLD, Australia. 4019 Ph. 07 8831851 Intl. 617 8831852 Fax 07 2831217 Intl. 617 2831217 TABLE OF CONTENTS CONTENTS PAGE 1.0 BACKGROUND 1 1.1 THE CD-ROM SOFTWARE INTERFACE 1 1.2 CD-SHARE - WHAT IT IS AND WHY WE NEED IT 2 2.0 CONFIGURING A CD-SERVER 5 3.0 CONFIGURING A CD-WORKSTATION 5 4.0 COMMAND LINE SWITCHES 9 4.1 CD MANAGER COMMAND LINE SWITCHES 9 4.2 CD REDIRECTOR COMMAND LINE 11 4.3 CD-SERVER COMMAND LINE SWITCHES 11 5.0 CACHING YOUR CD-ROM DRIVES - CD-CACHE 13 6.0 ADVANCED TOPICS 15 6.1 MEMORY USAGE 15 6.2 OPTIMIZING CD-SERVE PARAMETERS 16 FOR A NON-DEDICATED SERVER 6.3 OPTIMIZING CD-CACHE PARAMETERS 17 6.4 RUNNING CD-SERVE AND CD-CACHE IN DEDICATED MODE 19 7.0 QUESTIONS AND ANSWERS 20 Page 1 1.0 BACKGROUND 1.1 THE CD-ROM SOFTWARE INTERFACE When you purchase a CD-ROM drive and controller card for your PC you will usually also receive a disk containing a software device driver for the drive and a program written by MicroSoft Corp called the "MS-DOS CD-ROM Extensions" (MSCDEX.EXE). Device drivers are programs that are loaded by including them in a line in the CONFIG.SYS file on your DOS boot disk. A device driver is a software program with a standard DOS interface which allows DOS to talk to hardware devices which it knows nothing about. Although you don't see it DOS actually talks to your disks via an internal device driver ! The device driver supplied with your CD-ROM drive(s) allows DOS to interface to the CD-ROM drive without actually knowing the hardware specifics of the drive. This is how DOS can interface to various different brands of drives with different hardware interfaces - it simply talks via the device driver which does know about the hardware. There are two different classes of device drivers - character and block device drivers. An example of a character device driver are the internal DOS devices named CON (your console) and PRN (your LPT1) since they work a character at a time. Your disk drives are block devices since they transfer data to and from memory in blocks (e.g. a typical cluster (block) size for a disk might be 2K bytes. Character device drivers and addressed by name (e.g. CON, PRN, COM1, etc) whereas block type device drivers are allocated a drive letter by DOS in the range A: to Z:. A single device driver can control a number of drives, in fact up to 255. Since DOS only allows block device drive names A: to Z: this limits the practical total number of drives to a total of 26 minus any physical hard and floppy disk drives that are installed. If you had two floppy disks and one hard disk installed (A;, B: and C:) and a device driver named 'DEVICED' was installed controlling 3 block devices the system would be as follows : ⁄ƒƒƒƒ A: ≥ √ƒƒƒƒ B: ≥ √ƒƒƒƒ C: DOSƒƒƒƒƒƒ¥ ⁄ƒƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒ E: ≥ ≥ ≥ ≥ ¿ƒƒƒ¥ DEVICED √ƒƒƒƒ≈ƒƒƒƒ F: ≥ ≥ ≥ ¿ƒƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒ G: Fig. 1 Page 2 DOS automatically gives block devices the next available drive letter(s) when the device driver is installed in the config.sys file. If CD-ROM's were normal block device that would be the end of the story, however a single CD-ROM can hold a massive 550 MBytes of information - far more than DOS was designed to manage on a single block device. To overcome this limitation MicroSoft wrote some extensions to DOS known as the "MS-DOS CD-ROM Extensions" (MSCDEX). MSCDEX uses the networking drive redirection features built into DOS versions 3.1 and later to create a logical drive for each drive attached to each device driver specified on the MSCDEX command line when the extensions are started. MSCDEX is not a device driver, it is a "Terminate and Stay Resident" (TSR) program which runs and returns to DOS but remains in memory to it's work in the background. So that CD-ROM device drivers won't be installed by DOS as block devices the device driver header tells DOS that they are character devices (even though they aren't). CD-ROM device drivers are block device drivers that appear to DOS as character devices but have a special signature so that MSCDEX and other software wishing to talk to the CD-ROM via the device driver can recognize them as CD-ROM devices. If our previous example (Fig. 1) of DOS with a three drive device driver were replaced by MSCDEX and a device driver (CDDRIVER) driving three CD-ROMS the layout would now be as follows : ⁄ƒƒƒƒ A: ≥ √ƒƒƒƒ B: ≥ √ƒƒƒƒ C: DOSƒƒƒƒƒƒ¥ ⁄ƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒ E: ≥ ≥ ≥ ≥ ≥ ≥ ¿ƒƒƒ¥ MSCDEX √ƒƒ¥ CDDRIVER √ƒƒ≈ƒƒƒƒ F: ≥ ≥ ≥ ≥ ≥ ¿ƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒ G: Fig. 2 When MSCDEX or any other software calls a CD-ROM device driver it specifies which drive (or unit) it wishes to access by specifying a number beginning with zero. It figure 2 the logical drives E:, F: and G: would be drives 0,1 and 2 to CDDRIVER. 1.2 CD-SHARE - WHAT IT IS AND WHY WE NEED IT As well as making CD-ROM's appear as normal (large capacity) disk drives, MSCDEX supplies a number of other services to applications software that calls MSCDEX directly. Although networks such as ArtiSoft's LANtastic can redirect a CD-ROM drive so that it appears as an extra drive on a network workstation, Page 3 CD-ROM software that requires MSCDEX to run won't work. To make matters even worse some CD-ROM software bypasses MSCDEX completely and talks directly to the CD-ROM device driver. This is where CD-SHARE comes in. The CD-SHARE software contains CD-Server and CDWORK/CD-Redirector. CDServer is a TSR program which is run on the network computer which has the CD-ROM drives fitted and the appropriate CD-ROM device drivers installed. CDWORK.SYS and CD-Redirector are run on workstations which wishes to access CD-ROM devices on CD-Servers. CDWORK.SYS appears as a local CD-ROM device driver, however it passes and device requests onto CD-Redirector which in turn passes the requests to the appropriate CD-Server for processing. The results of the request are passed back to CD-Redirector/CDWORK.SYS and then back to the application which called CDWORK.SYS . CDWORK.SYS therefore appears to applications programs (including MSCDEX) as a local CD-ROM device driver. The CD-Manager program allows you to alter the number of drives that CDWORK.SYS appears to be controlling, and to connect each of those logical drives to a CD-ROM drive on a network machine running CD-SERVER. Because CD-ROM seek times and data transfer rates are so slow sharing a single CD-ROM amongst a number of users usually causes applications on workstations to run unacceptably slow. Because of this the CD-SHARE software suite also includes CD-CACHE which is a CD-ROM caching program written specifically to run in conjunction with CD-SHARE. When CD-CACHE running, when a request to read CD-ROM data occurs CD-CACHE checks to see if it has already been read. If not then the data is read from the CD-ROM and stored in the cache as well as being passed back to the calling software. If a request for data which is already in the cache occurs then the data is returned directly from the cache without any access at all to the CD-ROM. The CD-CACHE algorithm ensures that the most frequently read data (directories, etc) are always kept in the cache, this improves response times even when only one users is running programs from the CD-ROM. CD-CACHE can use conventional or extended memory up to 32 MBytes. The networking version of figure 2 using CD-SHARE would appear as follows : ⁄ƒƒƒƒ A: ≥ √ƒƒƒƒ B: ≥ √ƒƒƒƒ C: ⁄ƒƒƒƒƒƒƒƒø DOSƒ¥ ⁄ƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒø ⁄ƒƒƒƒƒø ≥ √ƒƒƒ 0 ¿ƒ¥ MSCDEX √ƒ¥ CDWORK √ƒ¥ CDR ≥-----≥ CDS √ƒ¥CDDRIVER√ƒƒƒ 1 ¿ƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒŸ ^ ¿ƒƒƒƒƒŸ ≥ √ƒƒƒ 2 ≥ ¿ƒƒƒƒƒƒƒƒŸ ^ Network Connection ƒƒŸ Drive Nos.ƒƒƒŸ Fig. 3 Page 4 Where : 1. CDWORK is the CD-Share CD-ROM device driver 2. CDR is the CD-Redirector 3. CDS is the CD-Server Note that figure three is a very simple configuration. Each copy of CDS which is started on a CD-Server is started up with a unique name and can be attached to multiple device drivers on the server computer. Using CD-Manager (CDM) each logical drive on CDWORK may be connected to any CDServer\Device\Drive. For Example SERVERS DEVICE DRIVERS DRIVES ⁄ƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒ 0 +-------≥ CDSERV-1 √ƒƒƒ¬ƒƒ¥ DRIVER1 √ƒƒ¥ | ¿ƒƒƒƒƒƒƒƒƒƒŸ ≥ ¿ƒƒƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒ 1 | ≥ ⁄ƒƒƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒ 0 | ¿ƒƒ¥ DRIVER2 √ƒƒ≈ƒƒƒƒƒ 1 | ¿ƒƒƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒ 2 | | ⁄ƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒ 0 +-------≥ CDSERV-2 √ƒƒƒƒƒƒ¥ DRIVER1 √ƒƒ≈ƒƒƒƒƒ 1 | ¿ƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒ 2 | | ⁄ƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒ 0 +-------≥ CDSERV-3 √ƒƒƒ¬ƒƒ¥ DRIVER1 √ƒƒ¥ | ¿ƒƒƒƒƒƒƒƒƒƒŸ ≥ ¿ƒƒƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒ 1 | ≥ ⁄ƒƒƒƒƒƒƒƒƒƒƒƒø ⁄ƒƒƒƒƒ 0 | √ƒƒ¥ DRIVER2 √ƒƒ≈ƒƒƒƒƒ 1 | ≥ ¿ƒƒƒƒƒƒƒƒƒƒƒƒŸ ¿ƒƒƒƒƒ 2 | ≥ ⁄ƒƒƒƒƒƒƒƒƒƒƒƒø | ¿ƒƒ¥ DRIVER3 √ƒƒƒƒƒƒƒƒ 0 | ¿ƒƒƒƒƒƒƒƒƒƒƒƒŸ | | | WORKSTATION | | DEVICE DRIVER ATTACHED TO DRIVES | | ⁄ƒCDSERV-1\DRIVER2\2 = 0 | ⁄ƒƒƒƒƒø ⁄ƒƒƒƒƒƒƒƒø≥ +-------≥ CDR √ƒ¥ CDWORK √≈ƒCDSERV-3\DRIVER3\0 = 1 ¿ƒƒƒƒƒŸ ¿ƒƒƒƒƒƒƒƒŸ≥ ¿ƒCDSERV-1\DRIVER1\1 = 2 Fig. 4 Note that since CDWORK simulates a CD-ROM device driver, there is no need to run MSCDEX on workstations running software that talks directly to the CD-ROM device driver. Also CD-Server is a non-dedicated server, this means that CDR and CDWORK may also be run on the server which may then log into and use devices made networkable by it's own copy of CD-Serve as well as other CD-Servers. Page 5 2.0 CONFIGURING A CD-SERVER 1. Install the CD-ROM drives, controllers, etc. and device drivers then test run the drives and programs as if the system were not to be networked to make sure everything is okay before adding the CD-Server. 2. If you have run MSCDEX in step 1, then re-boot the computer and DON'T run MSCDEX. Copy the CDServer (CDS.EXE) from the CD-Share distribution disk onto your system boot disk. 3. Make sure your network NETBIOS driver has been installed (with LANtastic this is AILANBIO, LANBIOS, or LANBIOS2). You won't need any other networking software on a CD-ROM workstation or a CD-Server in order to run the CD-Share programs. (You can still run network re-directors, non-dedicated servers, etc. if need be). 4. Assuming you wish to allow five logged in users, have named your CD-ROM device drivers DRIVER1, DRIVER2, etc (You will have specified the driver names on the "DEVICE=" line for the drivers in the config.sys file. Typical names take the form MSCD001, MSCD002, etc) and we wish to call our CD server cdserver1 enter the following command line : CDS CDSERVER1 device=DRIVER1 device=DRIVER2 verbose users=5 The "device=DeviceName" section may be repeated up to eight times. CD-Serve can handle up to 32 drives (e.g. four device drivers each driving eight drives, or eight drivers each driving four drives, one driver driving eight drives and four drivers driving six drives, or any mix). The verbose option is optional and causes CDS to indicate the names of connected device drivers as they are attached to confirm that the command line was accepted correctly. The "device=" section may be abbreviated to "d=" to fit more switches on the command line. CDS has more command line switches, they are covered in the "Advanced Topics" section. Note that after CDS has been run, all connected device drivers are effectively removed from the DOS device list so they can't be accessed by any other software. If you need to access the device drivers in order to gain access to the CD-ROM(s) from software running locally on the server you will have to configure the server as a workstation as well. 3.0 CONFIGURING A CD-WORKSTATION 1. Copy the programs CDWORK.SYS, CDR.EXE (CD-Redirector), and CDM( CD-Manager) onto the workstation disk. CDWORK.SYS should be in the root directory, CDR.EXE and CDM.EXE should be in a directory which is on the PATH. Page 6 2. Insert a line similar to that following in the config.sys file on the workstation boot disk : DEVICE=CDWORK.SYS [DEVICE_NAME] Where DEVICE_NAME is the name that MSCDEX or any other CD-ROM software will use to access the CD-ROM driver. Typical examples might be : DEVICE=CDWORK.SYS MSCD001 OR DEVICE=CDWORK.SYS CDWORK We will assume that the name CDWORK is used in future discussion. Whatever you use, make sure that the name doesn't conflict with a name you have given to any other device drivers (e.g. if you are setting up a non-dedicated CD-Server you will have both CDWORK.SYS and real CD-ROM device drivers installed in the config.sys file). 3. You will now have to re-boot the computer so that CDWORK.SYS is installed. CDWORK.SYS will sign on with a line similar to CDWORK Installed - Copyright Digital Solutions during the boot sequence. 4. Make sure that your network NETBIOS driver has been installed. Assuming you wish to call your CD Workstation CDW1 and you wish to redirect to a maximum of two CDROM's simultaneously enter the following command line : CDR CDW1 2 The actual syntax for the CDR command line is : CDR [Station Name] {Maximum Drives} where [] indicates that the parameter is mandatory and {} indicates that the switch is optional. If "Maximum Drives" is not specified it defaults to one. This is all that usually required since CD-Manager (CDM) can be used to disconnect the redirected CD-ROM drive from any CD Server device and re-connect to another at will. Also MSCDEX uses an additional 4K of memory for each logical drive on a device driver. 5. You can now use CDM to connect to devices and drives on any CD-Servers that are on line. To log into and connect to our CDSERVER1, DEVICE1, DRIVE 0 that we set up in the previous section, enter the following command line : CDM V IN:ON +:0=\\CDSERVER1\DEVICE1\0 Page 7 After CDM connects output similar to the following should appear on the screen : C:\CDM V IN:ON +:0=\\CDSERVER1\DEVICE1\0 DEVICE1 : Units = 2 CD - REDIRECTOR STATUS.... Connected servers.. \\CDSERVER1 Drives.. Drive 0: Connected to \\CDSERVER1\DEVICE1\0 Drive 1: NOT Connected Total Servers Attached : 1 Total Drives Attached : 1 Maximum Drives Attached : 2 Activity Indicator is : ON at Row 1, Column 80 C:\ Fig. 5 Let's analyze the command line to set what we've done. The first switch V{erbose} tells CDW to work in verbose mode. This is why the line DEVICE1 : Units = 2 appeared, and why the CD Redirector status was listed in full. The next switch IN{dicator}:ON tells CDM to turn on the CD Redirector activity indicator. This causes a small activity indicator to flash on the workstation as CD-ROM activity is in progress. By default the position of this is row one, column 80 on the screen (upper right corner), see "CDM Command Line Switches" for details on how to change this position. The next switch requires a little more description : +:0=\\cdserver1\device1\0 The + option tells CDM to add a new connection to CDWORK, in Page 8 this case to a drive 0, on a device named "device1" on a CD Server named "cdserver1". The actual syntax is as follows : +:[Local Drive Number]=\\[Server Name]\[Device Name]\Drive Where a device named "Device Name" be attached to a CD Server named "Server Name" and that device must have a drive number "Drive". If you now run the Microsoft extensions on the workstation specifying the name that you gave CDWORK.SYS (we'll use CDWORK as the name) you should get the following response : C:\mscdex /d:cdwork MSCDEX Version 2.10 Copyright (C) Microsoft Corp. 1986, 1987, 1988, 1989. All rights reserved. Drive D: = Driver CDWORK unit 0 Drive E: = Driver CDWORK unit 1 C:\ Fig. 6 Note that your drive letters may not necessarily begin at D: depending upon the drives installed in your computer and any redirected network drives you may have. If you now type : DIR D: You should now get a directory listing of the root directory of the disk in your CD-ROM drive. Note that if you now type in DIR E: You will get an error message from MSCDEX stating that the drive is not ready, this is because drive E: which is attached to DRIVE 1 on CDWORK is not connected to a server device (see Fig. 5). Now that MSCDEX has been run you may refer to the CDWORK drives by their drive number, or by their MSCDEX drive letter when using CDM. The - CDM command line switch allows a drive connection to be removed e.g. CDM -:0, or CDM -:D Would cause CDWORK drive 0 (Fig. 5) to be disconnected, or Page 9 CDM LOGOUT:CDSERVER1 Would cause all connections to CDSERVER1 to be removed. 4.0 COMMAND LINE SWITCHES 4.1 CD MANAGER COMMAND LINE SWITCHES The syntax of the CD Manager (CDM.EXE) command line is as follows CDM {switches} Where {switches} represents any of the following switches, each separated by a space. Note that any characters between {} braces are optional, the {} characters do NOT form part of the switch. Square braces [] indicate that the words between the [] are a name and should not be entered as shown. i.e. The name of a Device, CD Server, or Drive Number should be substituted for the [name] entry (the [] characters are not required. e.g. To indicate that a device name is required we might say [Device Name], when CDM is actually run we might use DEVICE1 instead of [Device Name]. In all cases a = character may be substituted for the : character in the following list. Switch Function V{erbose} Causes verbose operation of CDM. CDM will report various activities as they are processed and will cause CDM to show a CD Redirector status listing after all other switches have been processed. Sh{ow} Causes CDM to display CD Redirector status after all other switches have been processed. Logo{ut}: Syntax Logout:Server_Name Causes all CDWORK drive connections to CD Server "Server_Name" to be deleted and the connection to "Server_Name" to be removed. +: Syntax +:[Local Drive]=\\[ServerName]\[DeviceName]\[Drive] Attaches the CDWORK drive [Local Drive] to [Drive] on a device named [DeviceName] on a CD Server named [ServerName]. For [Local Drive] either the local CDWORK drive number or the drive letter may be used if MSCDEX has been run. [Drive] may be replaced by ALL if you want all of the drives on [DeviceName] to be attached to CDWORK beginning with CDWORK Page 10 drive [Local Drive]. e.g. to Connect local drive 1 to [Drive] 2 on [DeviceName] MSCD001 on [ServerName] CDSERVER1 the following switch would be used +:1=\\CDSERVER1\MSCD001\2 If MSCDEX had been run and Local Drive number corresponded to drive E: then the following syntax could also have been used +:E=\\CDSERVER1\MSCD001\2 -: Syntax -:[Local Drive] Disconnects [Local Drive] from the device it is currently attached to. [Local Drive] may be either the CDWORK logical drive (unit) number or the MSCDEX drive name if MSCDEX has been run. Dr{ives} Syntax Drives:[New Number of Local Drives] Alters the number of logical drives that CDWORK can redirect. This switch will not be accepted if MSCDEX has already been run. In{dicator} Syntax Indicator:[On|Off]{@Row,Column} Turns the CD Redirector activity indicator On or Off depending upon whether On, or Off is specified after the : . If On is specified you may optionally specify the screen coordinates by following On with @Row,Column ; where valid ranges for row and column are 1 to 25 and 1 to 80 respectively. The default position for the indicator is 1,80. For example to turn the indicator on at row 25, column 80 the following switch would be used in:on@25,80 or to turn it off in:off Note that if in:on is specified without a new position, then the previous position setting is retained. Page 11 4.2 CD REDIRECTOR COMMAND LINE The CD Redirector (CDR.EXE) command line must contain a unique name for the CD Redirector session and can contain an optional number of Local Drives specifier for CDWORK. CDR [Unique Name] {Number of Local Drives} e.g. CDR STN1 1 The number of local drives defaults to one if not specified. Since MSCDEX uses an extra 4K of ram per local drive, a figure of 1 is recommended if MSCDEX is to be used. Since it is unlikely that a workstation will be accessing more than one CD-ROM simultaneously this does not impose a limitation as CDM can be used to alter the actual CD-ROM drive that the single local drive is connected to at any time. Note that providing MSCDEX hasn't been run CDM.EXE can also be used to alter the number of local drives. CDR can be logged into a maximum of five CD Servers at any one time. Local Drives can range from one to twenty five. 4.3 CD-SERVER COMMAND LINE SWITCHES The syntax of the CD Server (CDS.EXE) command line is as follows CDS [Server_Name] device=device_name {switches} [Server_Name] a unique name which is used to represent the CD Server on the network. At least one device must be specified. Where {switches} represents any of the following switches, each separated by a space. Note that any characters between {} braces are optional, the {} characters do NOT form part of the switch. Square braces [] indicate that the words between the [] are a name and should not be entered as shown. i.e. The name of a Device, CD Server, or Drive Number should be substituted for the [name] entry (the [] characters are not required. e.g. To indicate that a device name is required we might say [Device Name], when CDS is actually run we might use DEVICE1 instead of [Device Name]. In all cases a = character may be substituted for the : character in the following list. Switch Function D{evice} Syntax Device:[Device_Name] Page 12 where [Device_Name] is the named of a CD-ROM device driver already installed on the server. This switch may be used a maximum of eight times connecting to a maximum of 32 drives per server (each device driver can handle multiple drives - the total of these drives must not exceed 32). Device drivers to which CDS attaches are removed from the DOS device list so other programs can no longer access the device(s). Us{ers} Syntax Users:[Maximum Number of logged in CD users] Note that a NETBIOS session is required for each logged in user. CDS DOES NOT check that your NETBIOS can support the number of sessions corresponding to your Users specification, it is the responsibility of the network configurer to ensure that enough netbios sessions will be available. (Up to 254 with LANtastic) Bu{ffer} Syntax Buffer:[Buffer Size in sectors] e.g. Buffer:4 Specifies the size of the network transfer buffer used to pass CD ROM data to CD workstations. The actual buffer size is approximately 2K by the specified buffer size. The default Buffer Size is three sectors (about 6K). Larger buffers improve performance but use more memory when CDS is installed leaving less room for other programs to run (This is not a consideration when running a CD Server in dedicated mode). Note that one buffer is allocated PER network task (see "Tasks") Ta{sks} Syntax Tasks:[Number of Network Tasks] e.g. Tasks:3 The network tasks figure determines how many network CD requests the server can handle simultaneously. The default is one. On a non-dedicated server the law of diminishing returns is reached at a figure of about five tasks. Three tasks is usually adequate, use two if memory is tight. 5.0 CACHING YOUR CD-ROM DRIVES - CD-CACHE Page 13 CD-CACHE is a caching program specifically designed to work in conjunction with CD-Serve on a CD-ROM server. Because of the slow access times of CD-ROM drives use of CD-CACHE is almost essential if three or more than three users will be accessing the CD-ROM simultaneously. In fact using CD-CACHE will usually speed up response times even when only one user is accessing the CD-ROM. CD-CACHE can use conventional, extended, expanded, or XMS memory for caching purposes CD-CACHE will cache any accesses to any of the CD-ROM drives (i.e. up to 32) that are being managed by CD Serve (CDS.EXE). Like CDS.EXE CD-CACHE (CDC.EXE) is a TSR program. This means that when you run CDC from the command line it will install itself and return to the DOS prompt while remaining in memory to perform CD caching as necessary. CDC will not install unless CDS has already been installed. CDC has a number of command line switches, the two that will most commonly be used are those that specify the type of memory CDC is to use for caching purposes and the amount of memory to use for caching. The syntax of the CD Cache (CDC.EXE) command line is as follows CDC {switches} Where {switches} represents any of the following switches, each separated by a space. Note that any characters between {} braces are optional, the {} characters do NOT form part of the switch. Square braces [] indicate that the words between the [] are a name and should not be entered as shown. i.e. A number of KBytes of memory to be used would be substituted for the [Cache Size in Kbytes] entry (the [] characters are not required. When CDC is actually run we might use 1000 instead of [Cache Size in KBytes]. In all cases a = character may be substituted for the : character in the following list. Command line switches are not case sensitive, i.e. TYPE is the same as Type or typE. Switch Function Type Syntax Type:{Conv|Ext|Ems|Xms} e.g. TYPE:CONV means to use conventional memory (below the 640K boundary) for caching. TYPE:EXT for Extended Memory TYPE:EMS for Expanded memory TYPE:XMS for XMS memory Page 14 The default is Conventional if no TYPE switch is used. Size Syntax Size:[Cache Size in KBytes] e.g. type:1000 for a 1MByte cache. The default is to use ALL of the specified type of cache memory if no size switch is found. Note that if you use all of conventional memory as cache it is preferable to use the Dedicate CDC switch to cause the CD Server to run dedicated, this will always use all of conventional memory for caching as well as improving performance dramatically and leaving you the option of unloading CDC at any time without re-booting the CD Server. See the "Dedicate" CDC switch for more detail. If you run CD-CACHE not dedicated and use all available conventional memory for caching there will be NO MEMORY LEFT TO RUN OTHER PROGRAMS. Ded{icate} Causes CD Cache to run the CD-Server in dedicated mode. This improves CD-Server performance dramatically (5 to 10 fold) and will add any remaining conventional memory available after CD Cache has loaded to the cache memory. E.G. if you have specified 1MByte of extended memory as cache and use the dedicate switch, and CD Cache finds that 500K of conventional memory remain available after it has loaded - your total cache size would be 1.5MBytes. When CD Cache is run in dedicated mode pressing the Esc key on the CD-Server keyboard will unload CD Cache and return to the DOS command line, leaving the CD Server as a non-dedicated, non-cached (as far as CD ROM's are concerned) server. Buff{er Sectors} Syntax Buffer:{Buffer Size in Sectors} When CD-Cache performs any CD-ROM reads it ALWAYS reads the same number of sectors into cache memory then returns the requests sectors from the cache to CD Server. For optimum performance the Buffer Size set for CD-Cache should be a multiple of that set for CD Serve. The default for CD Serve is three sectors and the default for CD-CACHE is six. As you can see the default of six for CD-Cache will be a multiple of Buffer settings for CD Server of one, two, or three sectors. The maximum buffer size setting is 25 sectors (about 64KBytes). The buffer Page 15 size you choose will be determined by the amount of conventional and cache memory you are willing to let CD-Cache use and the performance you require from the server. See the "Advanced Topics" section for information on how to make decisions on the best combinations of options to select for CD Server and CD Cache to optimize performance for your application. An example command line for running CD Cache in dedicated mode using 2 MBytes of extended memory would be as follows : CDC Type:Ext Size:2000 6.0 ADVANCED TOPICS 6.1 MEMORY USAGE The amount of conventional memory used by the various CD Share programs and MSCDEX after being loaded is listed below. NOTE: 1K = 1024 Bytes PROGRAM MEMORY USED CDWORK.SYS < 650 Bytes CDR.EXE 8 KBytes CDS.EXE 12K + Users * 106 + Tasks * (BufferSecs*2532 + 225) e.g. 10 Users, 2 tasks, 5 sectors per buffer = 12K + 10 * 106 + 2 * ( 5 * 2532 + 225) = 39118 Bytes = 38.2 K CDC.EXE Conventional Cache : 12K + Size of Cache Other : Buffer Size Bytes(BSB) = BufferSectors * 2532 Buffers in Cache (BIC) = CacheSize/BSB Conventional Memory used = 12K + BIC*34 + BSB e.g. Cache Size = 2MBytes of Extended Memory BufferSectors = 6 BSB = 6 * 2532 = 15192 Bytes BIC = (2000 * 1024)/15192 = 134(.8) Page 16 Conv Mem Used = 12K + 134*34 + 15192 = 31012 Bytes = 30.3 K MSCDEX.EXE 22K + 4K per logical drive (e.g. one device driver controlling 2 drives would use approximately 30K). This will vary slightly according to the version of MSCDEX. 6.2 OPTIMIZING CD-SERVE PARAMETERS FOR A NON-DEDICATED SERVER For a non-dedicated CD Server we are assuming that you want the server to use as little memory as possible. As with most things in real life you rarely get something for nothing - the more you prune back the resources available to CD Serve the poorer the performance will be. The trick is to strike a compromise which gives both acceptable memory usage and acceptable performance. As you can see from the CDS.EXE section in section 6.1 CDS conventional memory usage is governed by three parameters 1. Users 2. Buffer Sectors 3. Tasks Obviously you should only specify the number of CD users that you actually want the CD Server to be able to have connected at any one time. The "Buffer Sectors" parameter defines the size of the memory buffer that CDS uses to return CD ROM data to a CD Redirector. The larger this parameter is made (Max 25) the larger the block of data that the server can send to the CD Redirector in one hit. However the maximum figure of 25 sectors amounts to a buffer size of about 64K and there is one buffer allocated per network task, as you can see allocating large buffers and tasks can quite quickly gobble up huge amounts of memory. The number of tasks determines how many CD network requests that the CD Server can process at any one time. Performance will improve as the number of tasks is increased. The law of diminishing returns is reached for a non-dedicated server at a figure of about five tasks. The question then arises as to which combination is best for a non-dedicated server. The answer of course lies in the question "how much memory do you want left over after CDS has been run and what level of performance are you going to consider as satisfactory ?". For minimum memory usage both the Buffer Sectors and Tasks should be reduced to a minimum. The default buffer sectors setting is three, a setting of two is probably a good starting point if you a trying to minimize memory usage and Page 17 maintain reasonable performance. A Tasks setting of two will give a fairly substantial improvement over the default of one, improvements will be gradually decreasing as the number of tasks is increased through three, four, and five. With this background experimentation is probably the best indicator of what will be acceptable for your application. When evaluating performance it should be noted that CD ROM applications usually have long periods of disk inactivity interspersed with short bursts of activity when programs and images are loaded from the CD ROM. A simple method of gauging performance is to create a batch file on a number of workstations which reads a large number of files from the CD-ROM into a temporary file on a hard disk, deletes the temporary file then loops to the beginning - timing the loop will give an indication of performance. If you have this arrangement set up and you wish to re-boot the server in order to alter CDS parameters it is quite acceptable to simply re-boot the server. Each CD Redirector will eventually report an error and MSCDEX will give you the options Abort, Retry, or Ignore. After CDS has been re-run on the CD Server simply select Retry and the CD-Redirector will re-connect to the server and continue. 6.3 OPTIMIZING CD-CACHE PARAMETERS We will assume here that for a non-dedicated CD Server CD Cache will always be run using cache memory other than conventional memory; since you would have to use all of the conventional memory in order to make the cache of any use and if you do this you might as well run the CD Server in dedicated mode and get some real performance improvements ! As you can see from the calculations for CDC.EXE conventional memory usage when using extended memory, the additional memory that CDC uses beyond it's fixed code and data size is made up of two components 1. A single buffer the size of which is set by the "BufferSectors" command line switch. The default setting for this is 6 sectors or about 15 KBytes. 2. Cache Buffer management memory which amounts to 34 bytes for each time the buffer allocated at step 1 will fit into the cache memory size. From step 2 we can see that for a given amount of cache memory the amount of cache management memory required increases as the "Buffer Sectors" setting decreases. In the example calculation of section 6.1 for 2MByte of cache memory and 6 sectors per buffer we used 134 * 34 Bytes = 4556 bytes for cache management and 15192 bytes for the buffer for a total extra conventional memory usage of 19748 Bytes. If we halved the buffer size to three sectors we could used 269 * 34 = 9146 Bytes for management plus 7596 bytes for buffering for a total of 16742 bytes. As you can Page 18 see we have only reduced the consumption of conventional memory by 3K but we have more than doubled the fragmentation of the cache. As a general rule, the larger the Buffers per Sector setting the better as it allows the CD-ROM to read more information in a single disk read thus eliminating a seek from another position on the disk when sequential sectors are read from the server. However a quick glance at some files on a CD-ROM will reveal that many of the files (and the directories if you could see their size) are actually less than 20K in length. This means that since there is usually very little file fragmentation many of these files could be read with a single access from the CD ROM. Note that although CD-CACHE allocates 2532 bytes per sector so that it can cope with CD-ROM applications that request sector data in RAW mode (2532 bytes per sector) most applications read the CD-ROM in cooked mode which returns 2048 bytes per sector (2K). Thus a 12 sector buffer would generally read 24K bytes per read. Although CD-CACHE will accept buffer sizes up to 25 sectors, using values above 12 decreases the granularity of the cache for very little improvement in performance. For optimum performance the Buffer size should be set to a multiple of the BufferSectors setting used with CDS. The default CD-CACHE buffer size is set to six sectors, this is a good compromise between conventional memory usage and performance, and is also a multiple of the default CD-SERV buffer size of three sectors (Also of 2, and 1 !). You should choose your buffer sectors setting with the following things in mind: 1. If you are caching a large number of drives running different applications, then for a given cache size smaller buffers are going to increase buffer granularity and therefore more likely to keep more of the frequently used sections of each CD-ROM in the cache. 2. If you don't have much memory to use as cache memory smaller buffers are better as this will help to improve the granularity. 3. If you have plenty of cache memory in comparison to the number of CD-ROM's that are being cached then you can increase the buffer size to improve performance and reduce CD-ROM drive wear and tear while still achieving good granularity. 4. If you are running CD-CACHE in non-dedicated mode then you should choose a buffer size which results in an acceptable compromise between conventional memory used and granularity Page 19 6.4 RUNNING CD-SERVE AND CD-CACHE IN DEDICATED MODE If you want the ultimate in performance - dedicate your CD-ROM Server ! When using CD-CACHE you can optionally tell it to run CD Server in dedicated mode. This will give an immediate speed improvement of usually at least five hundred percent as well as allowing CD-CACHE to add all remaining conventional memory to it's cache buffers. As a bonus you can unload CD-CACHE and return the CD-Server to non-dedicated/non-cached operation at the touch of a key without disturbing and other network users using the CD-ROM's on the server. To run in dedicated mode simply include the "Dedicate" switch on the CD-Cache command line as follows : CDC Type:Extended Size:2000 Dedicated CD-Cache will respond with a message saying that it is installed and running CD-Serve in dedicated mode. To unload CD-Cache and return to non-dedicated CD Server operation simply press the Esc key. Network users logged in and using the CD-ROM at this time will notice nothing excepting for a dramatic decrease in performance. If a computer is being used specifically as a dedicated CD Server in order to share multiple CD ROM's with maximum performance then the memory constraints which are important when running in non-dedicated mode lose there importance. The CD Serve buffer size should be increased to about six sectors and tasks to about five. The CD-CACHE buffer size should also be set to at least twelve sectors (you should install plenty of cache memory). Read sections 6.2 and 6.3 (if you haven't already done so) to get a good understanding of the performance consequences of altering the CD-Serve and CD-Cache buffer sizes. Page 20 7.0 QUESTIONS AND ANSWERS Question : Does a network computer need to be set up as a network server or have a redirector or MSCDEX installed in order to be used as a CD-Server. Answer : No - All that is required of the network in order to run CD Serve on a computer is a NETBIOS network driver. Question : Do I need to run the network redirector on a CD ROM workstation. Answer : No - All that is required on the workstation is that CDWORK.SYS is included and given a device name in the CONFIG.SYS file on the workstation boot disk and that network NETBIOS network driver is installed before running CDR.EXE. Question : Do I need to run MSCDEX on a CD-ROM workstation. Answer : Only if your CD-ROM application requires MSCDEX. Many CD-ROM applications install themselves on the workstation hard disk then interface to the CD-ROM directly via the device driver (CDWORK.SYS in this case) - these applications usually only require MSCDEX for the initial installation (i.e. to copy the program files from the CD-ROM to the hard disk). Question : Can I use a CD-ROM workstation to perform normal network activities by running the network redirector. Answer : Yes - the CD Redirector and CDWORK appear simply as another device driver to both the network and to DOS. Question : Can I run CD Serve in dedicated or non-dedicated mode on a normal non-dedicated network server (e.g. LANtastic) Answer : Yes, although the activities of the two servers will serve to reduce the performance of both when running under heavy load conditions. Question : I cannot run my normal network redirector up after running CDR and MSCDEX Answer : MSCDEX is implemented as a network re-director. Your network redirector sees MSCDEX as a previously installed network redirector and refuses to install. The solution is to run MSCDEX after your Page 21 network redirector (and before your server if running the machine up as a non-dedicated network server e.g. LANtastic's SERVER.EXE). Question : After running MSCDEX I don't have enough memory to run my CD-ROM program. Answer : MSCDEX uses an extra 4K of memory for every drive on every device driver it is attached to. Make sure that when running CDR.EXE or CDM.EXE that you don't set the number of drives supported by CD Redirector to more than one. You can then use CDM.EXE to alter this one logical CD-ROM drive to different CD-ROM drives on any CD Servers on the network as and when required. Question : After I run MSCDEX I get devices with names like G.\A. H.\B. I.\C. In my network connection manager's list of redirected drives and I can't remove the connection. Answer : MSCDEX functions in exactly the same way as your network redirector - it uses the DOS redirection functions and therefore the CD-ROM logical drives appear in the list of redirected drives. Because your network redirector doesn't recognize these as it's own re-directed drives it won't alter these connections. Page 22