Hard Drive: WESTERN DIGITAL: SP-4200F PIRANHA 209MB 3.5"/HH SCSI2 FAST
S P - 4 2 0 0 F P I R A N H A WESTERN DIGITAL
NO MORE PRODUCED Native| Translation
------+-----+-----+-----
Form 3.5"/HH Cylinders 1280| | |
Capacity form/unform 209/ MB Heads 8| | |
Seek time / track 14.4/ 5.0 ms Sector/track 40| | |
Controller SCSI2 SI/FAST Precompensation
Cache/Buffer 64 KB SEGMENTED Landing Zone
Data transfer rate 1.500 MB/S int Bytes/Sector 512
10.000 MB/S ext SYNC
Recording method RLL 2/7 operating | non-operating
-------------+--------------
Supply voltage 5/12 V Temperature *C 5 50 | -40 60
Power: sleep W Humidity % 8 80 | 5 95
standby W Altitude km -0.305 3.048| -0.305 12.192
idle 5.0 W Shock g 10 | 50
seek 8.5 W Rotation RPM 3610
read/write 6.2 W Acoustic dBA 40
spin-up W ECC Bit 56
MTBF h 87000
Warranty Month 12
Lift/Lock/Park YES Certificates CSA,FCC,IEC950,UL1950,VDE
Layout
WESTERN WDSP4200/WDSP4200F INSTALLATION GUIDE S0834 79-000543-000
+---------------------------------------------------------+ |+-+ |XX Power ||x| |XX ||x|W3 | ||x| |XX1 |1-+ |XX ++ LED REVISION 1 |XX I ++ |XX N |+-+ |XX T ||x|W1 |XX E ||x| |XX R |1-+ |XX F | |XX A | |XX C | |XX E | |XX | |XX | |XX +---------------------------------------------------------+
+---------------------------------------------------------+ |+-+ |XX Power ||x|W3 |XX ||x| | |1-+ |XX1 |+-+J4 |XX |+-+ REVISION 2 |XX I ++LED |XX N +++--+J5 |XX T |+--+ |XX E |+-+ |XX R ||x|W1 |XX F ||x| |XX A |1-+ |XX C | |XX E | |XX | |XX | |XX +---------------------------------------------------------+
Jumpers
WESTERN WDSP4200/WDSP4200F INSTALLATION GUIDE S0834 79-000543-000
Jumper Setting
==============
x = Factory default setting
Revision 1
----------
Termination
| Reserved Spin-up
| LED | SCSI ID Reserved| +-ANSI/APPLE SCSI
+-+-+ | | +--+--+ | | | +Parity
13 11 9 7 5 3 1 LED 7 5 3 1
---+--+--+--+--+--+--+--+---+---+-----+--+--+--+--+---+ +----
|XX|XX|XX|XX|XX|XX|XX| | O | |XX|XX|XX|XX| | |
----+--+--+--+--+--+--+--+---+---+-----+--+--+--+--+---+---+------
14 12 10 8 6 4 2 8 6 4 2
+--------+---------+ +----+----+
W3 W1
Revision 2
----------
Termination Connector for
| Optional Fuse
|Reserved | Reserved
| | SCSI ID LED | LED | Spin-up
| | +--+--+ | | | | | +----ANSI/APPLE SCSI
9 7 5 3 1 J4 LED J5 9 7 5 3 +1--Parity
---+--+--+--+--+--+----+---+---+--+--+--+--+--+---+ +----
|XX|XX|XX|XX|XX| xx | O | X |XX|XX|XX|XX|XX| | |
----+--+--+--+--+--+----+---+---+--+--+--+--+--+---+---+------
10 8 6 4 2 10 8 6 4 2
+------+-----+ +-----+-----+
W3 W1
The Piranha SP4200 and SP4200F drives have two jumper blocks, W1 and
W3, located on either side of the internal LED. Some Piranha
revisions have a third jumper, J4, and a fuse socket, J5.
If the drive is supplied with the faceplate installed, you must re-
move it to access the jumpers.
W3 SCSI Device ID ----------------- +----------+-----------------------+ | SCSI ID | Jumpers | | | 5-6 | 3-4 | 1-2 | +----------+-------+-------+-------+ |x 0 | OPEN | OPEN | OPEN | +----------+-------+-------+-------+ | 1 | OPEN | OPEN | CLOSED| +----------+-------+-------+-------+ | 2 | OPEN | CLOSED| OPEN | +----------+-------+-------+-------+ | 3 | OPEN | CLOSED| CLOSED| +----------+-------+-------+-------+ | 4 | CLOSED| OPEN | OPEN | +----------+-------+-------+-------+ | 5 | CLOSED| OPEN | CLOSED| +----------+-------+-------+-------+ | 6 | CLOSED| CLOSED| OPEN | +----------+-------+-------+-------+ | 7 | CLOSED| CLOSED| CLOSED| +----------+-------+-------+-------+
Each device on the SCSI bus must have a unique device identifying
number in the range 0 to 7. W3 jumper pins 1 through 6 are used to
set the device ID.
Externally Activity LED
-----------------------
If your system configuration allows the use of an activity LED
external to the Piranha drive, you can power the LED from the drive.
Activity LED options if J4 is NOT present:
- W3 jumper pins 9-10 provide power for an external activity LED.
Activity LED options if J4 IS present:
- W1 jumper pins 9-10 provide power for an external activity LED. Jumper J4 also provides external LED power via a 2-pin 2-mm connector.
If you using the WD 5.25 Kit, refer to the LED installation
instructions in the kit. To install an external activity LED from the
system, connect the positive lead (anode) of the LED to pin 10 and
the negative lead (cathode) to pin 9.
SCSI Termination
----------------
The devices at each end of the SCSI bus must be terminated. Since the
SCSI cable is actually an extension of the bus, you must terminate
the devices physically located at the ends of the cable. All devices
between the ends of the cable must be unterminated. The host bus
adapter is unterminated if it is in the middle of the cable. If the
Piranha drive is to be at either end of the SCSI cable, the drive
must be terminated.
To terminate the Piranha drive, you must set a jumper, and you must
have termination power. Termination power can come from the SCSI bus
(directly or through a host bus adaptor) or from the drive which is
being terminated.
There are different jumper options for termination, depending on
whether the bus or the drive is to supply the termination power.
Consult your system or host adapter documentation to determine if
your SCSI bus supplies termination power. (Most systems do supply
termination power.) If your system does not, then you must use power
supplied by the Piranha drive.
The jumper options for termination are on the W3 jumper block. They
vary depending on which version of the Piranha you have.
Termination options if J4 is NOT present:
- To terminate the Piranha drive with termination power coming from the SCSI bus, leave the jumper shunt on pins 11-12. This is the factory default setting. If you are not sure whether your system supplies termination power, try this setting first, since is the most common.
- To terminate the Piranha drive with termination power coming from the drive, move the jumper shunt from pins 11-12 to pins 12-14. Note that this requires an uncommon sideways placement of the jumper shunt.
- To make the drive unterminated, remove the jumper shunt from pins 11-12. The unterminated setting is no shunts on pins 11 through 14.
Termination options if J4 IS present:
- To terminate the Piranha drive, leave the jumper shunt on pins 9-10. This is the factory default setting.
- To make the drive unterminated, remove the jumper shunt from pins 9-10.
- In the unusual event that power is not supplied by the host or another SCSI device, the Piranha can supply termination power. To enable termination power from the Piranha drive, you must procure and install a fuse in the J5 connector. Disconnect the power source before installing the fuse.
Parity Checking
---------------
The SCSI bus provides a parity bit to allpw parity checking of data
on the bus. Parity checking improves data reliability. The default
mode of the Piranha drive enables parity checking. To disable parity
checking, install a jumper shunt on W1 jumper pins 1-2
ANSI/Apple SCSI
---------------
Apple Computer products use the SCSI bus in a slightly different
manner than other computers. The Piranha drive supports both the
Apple SCSI implementation and the conventional ANSI SCSI implementa-
tion via W1 jumper pins 3 and 4. The default configuration (no jumper
shunt), enables ANSI SCSI. Install a jumper shunt on Pins 3-4 to
enable Apple SCSI.
Spin-Up at Power-On
-------------------
The Piranha drive can be configured to automatically spin up when
power is applied to the drive, or to spin up only on command from the
host. Regardless of whether automatic spin up is enabled, the drive
will always respond to the host command. A jumper shunt on W1 jumper
pins 5-6 enables automatic spin up at power-on. This is the factory
setting. To enable spin-up on command only, remove the jumper shunt
from pins 5-6.
Install
WESTERN WDSP4200/WDSP4200F INSTALLATION GUIDE S0834 79-000543-000
Notes on Installation
=====================
Drive mounting
--------------
horizontally vertically
+-----------------+ +--+ +--+
| | | +-----+ +-----+ |
| | | | | | | |
+-+-----------------+-+ | | | | | |
+---------------------+ | | | | | |
| | | | | |
| | | | | |
| +-----+ +-----+ |
+--+ +--+
Before Installing the Drive
---------------------------
Be sure that you have the following items before installing your new
drive:
- Computer system manual
- Operating system manual
- Host bus adapter and information, if applicable
- 50-pin interface cable, maximum 6 meters long
There are some other items you may require:
- You may need jumper shunts, available from your dealer, if you change the drive configuration.
- You may need a power Y-adapter if you are installing the drive as a second hard drive and you not have two internal power connectors.
- You may need a fuse if termination power is not supplied by the host or another SCSI device.
- Some systems require drive mouning rails. Check your computer system manual to determine if mounting rails are required. These rails can be purchased through your computer manufacturer or dealer.
- If you are installing the Piranha intelligent drive in a 5-1/4" drive bay, you need a 5-1/4" frame. This frame mounts on the drive and adapts it to the larger bay. Western Digital offers a 5.25 Kit, which may be purchased from your dealer.
The WD 5.25 Kit contains one 5-1/4" frame, two faceplates with LEDs,
and screws for connecting the drive frame and faceplate to the
Piranha drive.
Mounting Restrictions
---------------------
The Piranha drive may be mounted with the top, bottom, left, or
right side down, depending on the physical design of your system. The
Piranha is mounted with four 6-32 screws.
Screws which are too long will damaga the board components. Mounting
screws must engage no more than six threads (3/16 inch).
Caution
You may damage the Piranha drive or the host system if the interface
cable is not connected properly. Confirm that you are cabling the
drive to a 50-pin connector on the system or host bus adapter. Be
sure to match pin 1 on the cable to pin 1 on the connector. To
prevent incorrect correction, use a cable that has keyed connectors.
Cabling
-------
The Piranha SP4200 and SP4200F drives require a 50-pin cable not
longer than six meters. If multiple devices are attached to the SCSI
bus, the devices must be daisy-chained, using a cable with multiple
connectors. The ends of the cable must be connected to terminated
devices. If the cable contains more connectors than needed for the
devices on the bus, mid-cable connectors remain unused.
Power Connectors, Cables, and Fuse
----------------------------------
Power Connector 4 Pin: AMP P/N 770671-1
Mating Power Connector Body: AMP 1-480424-0
Pins: AMP 60619-4
Power Cable Wire Gauge 18 AWG
Mating SCSI Connector 50-Pin: MOLEX P/N 70248
Fuse Microfuse: 2-pin, 1 Amp, 125V, Little-
fuse P/N 272001
Mating External LED Connector Molex housing 50-57-9002. Power
provided is 15mA max. at +5VDC
Equivalent parts may be used.
Removing the Factory-Installed Faceplate
----------------------------------------
The Piranha faceplate is held on the drive by a hook on the upper
edge and two spring-fit retaining pins on the bottom that engage
holes in the drive base assembly.
1. Place the drive, faceplate up, on an antistatic surface.
2. Insert a ball point pen or similar tool in the retaining holes and
carefully press each retaining pin to disengage it from the hole.
3. Lift the faceplate straight up to free the hook on the top surface
of the drive.
Features
WESTERN WDSP4200/WDSP4200F INSTALLATION GUIDE S0834 79-000543-000
Overview
--------
The Western Digital Piranha SP4200 and SP4200F are 209.7 megabyte
disk drives suitable for use a new, upgrade, or replacement drives in
systems utilizing the Small Computer System Interface (SCSI), includ-
ing AT systems with SCSI Host Bus Adapters.
The SP4200 and SP4200F are distinguished by the synchronous data
transfer rate of the SCSI-2 interface:
- The SP4200 has a maximum transfer rate of 5.0 megabytes per second.
- The SP4200F has a maximum transfer rate of 10.0 megabytes per second.
Piranha also offers an average seek time of less than 15 milli-
seconds, and a 12.66 megabit-per-second media transfer rate.
Because of its compact, half-height size, the Piranha drive is easily
incorporated into the newest generation systems. It has been designed
for applications that demand a ombination of advanced processing
power and high performance, including highspeed desktop PCs, CAD/CAM,
engineering workstations, network file servers, and desktop publish-
ing. The Piranha ua a 3-1/2" drive that can also be used in a 5-1/4"
drive bay with a drive frame available from your dealer.
The Piranha drive is preformatted (low-level) and defect-free.
The Piranha drive offers the following features:
- Active SCSI termination, a patended Western Digital feature, incorporates unique termination electronics which allow termination of the drive via a single jumper. This significantly eases installation.
- Automatic head parking retracts the heads, on power down, to a safe, non-data landing zone and locks them into position.
- Piranha supports a comprehensive SCSI-2 command set, which allows 5 megabytes-per-second (SP4200) or 10 megabyte-per-second (SP4200F) Fast SCSI data transfers.
- Piranha includes CacheFlow, the industry's first adaptive, multi- segmented disk caching system.
CacheFlow constantly evaluates both the size and type of the data
request, dynamically partitons the 64-Kbyte buffer into caching seg-
ments, and automatically selects the appropriate caching mode for
optimum performance.
Seek Time
---------
+----------------------------------+--------+
|Track-to-Track msec. typ. | 5 |
+----------------------------------+--------+
|Average msec. typ. | 14.4 |
| msec. max. | 26 |
+----------------------------------+--------+
|Latency msec. avg. | 8.31 |
+----------------------------------+--------+
General
WESTERN TIPS
WESTERN DIGITAL 3.5-INCH DRIVES FREQUENTLY ASKED QUESTIONS ---------------------------------------------------------- 1) Will a Caviar drive work in my system? If your computer is 100% AT compatible and has either a 40-pin AT IDE interface on the motherboard or an IDE controller card with a 40-pin data cable.
2) What are the master/slave jumper settings on Western Digital
drives?
All Western Digital drives are configured the same. On the back of
the drive between the 4-pin power connector and the 40-pin data
connector, there is a jumper block J8 consisting of 6 pins.
Western Digital hard drives are shipped with a jumper shunt in the
neutral storage position (across pins 5 and 3) for future dual
drive use.
- If you are installing the Western Digital hard drive as the only hard drive in your system, leave the jmper shunt in the neutral storage posiition. Jumper shunts are not required for single hard drive installations.
- To designate the Western Digital hard drive as the master (C:), place a jumper shunt on pins 5-6
- To designate the Western Digital hard drive as the slave (D:), place a jumper shunt on pins 3-4.
3) What are the drive type and the drive parameters in the CMOS, for
Western Digital drives?
On top of the drive, the number of cylinders, heads and sectors
per track are printed on the label. Precomp and L-zone should be
set equal to the drive's cylinder count + 1. Select user type or
custom type (typically type 41 or 42) for your drive. This will
allow you to type in the parameters. Older systems that do not
offer a user type can either upgrade the system BIOS or set the
drive to drive type 1 (which should be a smaller drive size), and
run Ontrack Disk Manager from A drive to get the full capacity of
the drive. If you do not follow one of these procedures and your
system is pre-1994, you will be limited to the largest size drive
your BIOS will allow.
4) What is the Ontrack Disk Manager software that came with my drive
and what does it do?
Ontrack Disk Manager is the original hard disk installation
package that will initialize, partition, and prepare your hard
drive for use. Ontrack Disk Manager also allows you to access the
full capacity of the drive even when your system BIOS can't. It is
compatible with 32-bit disk access.
Note: Ontrack Disk Manager must be installed from floppy drive A. If
your A drive is a 5.25-inch floppy drive, copy the contents of your
Ontrack Disk Manager disk to a formatted 5.25-inch disk and re-run
Ontrack Disk Manager.
5) I just installed Ontrack Disk Manager on my Caviar drive and tried
to install DOS. DOS attempted to write to my drive and it
formatted my drive back to 528 MB which is my BIOS limitation. How
do I install DOS and still get the full capacity of my drive?
After Ontrack Disk Manager installation, you must create an
Ontrack Disk Manager rescue disk. There are two ways of
accomplishing this:
OPTION 1:
- Create a clean DOS bootable disk.
- Copy 2 files from the Ontrack Disk Manager disk to your bootable disk: XBIOS.OVL, and DMDRVR.BINs Create a CONFIG.SYS file on this bootable disk with these 3 lines: DEVICE=DMDRVR.BIN FILES=35 BUFFERS=35
- Remove the floppy and reboot the system.
- When you see the message "Press spacebar to boot from diskette", press the spacebar (system halts).
- Insert the rescue disk in the A: drive.
- Press any key (system resumes boot process).
- At the A: prompt, remove rescue disk, insert DOS installation disk and type SETUP.
- You can now install DOS without overwriting the Ontrack Disk Manager files.
OPTION 2:
- Create a clean DOS bootable disk.
- Insert Ontrack Disk Manager disk in the A: drive.
- At the A prompt, type: DMCFIG/D=A:. You will be prompted to insert a bootable floppy in the A: drive.
- Follow the prompts on the screen. Ontrack Disk Manager will ask you to change disks a few times.
- Continue until Ontrack Disk Manager is finished.
- Remove the floppy and reboot the system.
- When you see the message "Press spacebar to boot from diskette". Press the spacebar (system halts).
- Insert the rescue disk in A drive.
- Press any key (system resumes boot process).
- At A prompt, remove rescue disk, insert DOS installation disk and type SETUP.
- You can now install DOS without overwriting the Ontrack Disk Manager files.
6) CHKDSK or SCANDISK reports a few bad sectors. How do I go about
fixing the problem.
You can use the Western Digital defect management utility WDATIDE.
One of its options is the comprehensive surface analysis. This
procedure will mark all grown defects bad if indeed there are any
and it will compensate for the lost capacity by utilizing spare
tracks.
Note: This utility is data destructive. Back up all data on the drive
before using it. Due to the thoroughness of this operation, WDATIDE
can take quite a bit a time depending on the capacity of your drive.
7) Do I have to do anything with my original drive when adding a new
drive to my system?
Yes, one hard drive must be designated as the master drive
(preferably the newer, faster drive) and the other must be
designated as the slave drive. Typically, most drives need to have
a jumper placed on them to specify the Master or Slave position.
For information on non-Caviar hard drives, please contact the
appropriate manufacturer.
8) I installed my new drive and entered the drive parameters in the
CMOS, but the drive will not boot or it displays the message "HDD
controller failure."
Your drive must be partitioned and formatted before it will be
bootable. If your system will support drives larger than 528 MB,
and you have a copy of MS-DOS or PC-DOS version 5.0 or greater,
insert the setup diskette in your floppy drive and turn on your
computer. Follow the prompts and DOS will partition and format the
drive for you.
If you do not have a copy of MS-DOS or PC-DOS version 5.0 or greater,
you will need to boot from a bootable disk and then run the FDISK
command to partition your drive, and then format the drive using the
DOS FORMAT command. After running format, you should be able to
reboot your computer from your hard drive.
9) How can I use the full capacity of my Caviar drive of 540 MB or
greater?
You can use Ontrack Disk Manager to obtain full capacity if your
system does not support LBA mode. If your system does support LBA
mode, you can enable LBA in your CMOS setup utility.
10) How can I get 32-Bit Disk Access in Windows on my Caviar AC2540,
AC2700 or AC31000 in Windows 3.1x? If your BIOS supports the
drive at full capacity (i.e., the BIOS supports Logical Block
Addressing) you use WDCDRV.386, Western Digital's FastDisk device
driver. This driver is contained in a file named WIN31.EXE
available for downloading from our bulletin board (714/753-1234),
our Web server (WWW.WDC.COM), our FTP site (FTP.WDC.COM), our
forum on the Microsoft Network (Go word WDC), and our forum on
America On-line (keyword WDC). If your BIOS does not support LBA
mode and you have installed your drive using Ontrack Disk Manager
(v6.03 and above), run DMCFIG to install WDCDRV.386 and obtain
32-Bit Disk Access.
11) My drive will not spin up or spins down after a few seconds.
This is a drive failure. Return the drive to the distributor or
contact a technical support representative to receive a Return
Materials Authorization (RMA).
12) CMOS, FDISK and File Manager in Windows report less than the
capacity of my new drive, but CHKDSK reports the right number of
bytes. Which is correct?
Setup (CMOS) and FDISK use a binary definition of a megabyte
which is calculated at 1,048,256 bytes per megabyte. All hard
drive manufacturers and the DOS CHKDSK utility use a decimal
definition of a megabyte which is calculated at 1,000,000 bytes
per megabyte. This is why some utilities show 515 MB for a 540
megabyte drive and some show the actual number.
13) How Can I install OS/2 for Windows, OS/2 3.0 WARP, Windows NT
3.5x or Windows 95 on my drive which was initially installed
using Ontrack Disk Manager?
If you have Ontrack Disk Manager version 6.03, 6.03a, or 6.03b,
download the file named DMPATCH.EXE from Western Digital's online
services: ftp site: ftp.wdc.com
World Wide Web Site: http://www.wdc.com/
Microsoft Network (MSN) - Go word WDC
America Online (AOL) - Keyword: Western Digital
Western Digital's BBS at (714) 753-1234
This file has the latest Ontrack Disk Manager drivers which will
allow you to install OS/2 version 2.1x, OS/2 WARP, Windows NT 3.5x
or Windows 95 on your hard drive. Please read the included readme
file with this file for further detail.
14) My drive will work as a slave but not as a master (or vice-
versa).
Check master/slave jumpers on all drives. Also, some drive's speed
and timing differ drastically as to the initial spinup sequence. This
might confuse the system and cause one of the drives not to be
recognized. The best solution for this situation is to exchange
drives (make the master a slave and vice-versa).
15) My drive will not partition when I run FDISK. It hangs the system
or it displays the message: "Runtime error."
This is usually caused by corruption or damage to track zero. Use
the Western Digital utility WDFMT to format the drive. If that
does not help, call Western Digital Technical support at
1-800-ASK-4-WDC to get further instructions.
16) Can a hard drive be mounted on it's side, edge, or upside down?
Drives can be mounted on any side but it is preferable to mount
the drive right side up. It is also important to use all four
screws to hold the drive firmly in place.
Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.)
----------------------------------------------------------------
S.M.A.R.T. enables a drive's internal status to be monitored through
diagnostic commands at the host level.
The Caviar AC21600, AC32100 and AC32500 drives monitor read error
rate, start/stop count, spin-up retry count, and drive calibration
retry count. All of these attributes are updated and stored on the
hard drive in the reserved area of the disk. The hard drive also
stores a set of attribute thresholds that correspond to the
calculated attribute values. Each attribute threshold indicates the
point at which its corresponding attribute value achieves a negative
reliability status.
====================================================================
QUESTION
Which hard drive specification is most important to overall
system performance ?
- Host Transfer Rate
- Drive RPM (revolutions per minute)
- Disk Transfer Rate (Media Rate)
- Seek Time
- Cache Size
- PC Data Handling
- All of the above
Answer
The correct answer is actually a combination of "all of the above,"
keeping in mind most of the above specifications are interrelated
when it comes to optimizing system performance.
The pie chart illustrates the relative influence of factors affecting
drive performance during a typical random I/O operation (reading
and writing to a hard drive).
The major determinate of hard drive performance is mechanical
factors which are one hundred times slower than the high-speed
electronics contained in a drive.
Factors Affecting Hard Drive Performance
(In their relative order of importance)
MECHANICAL LATENCIES
Mechanical Latencies include both Seek Time and Rotational
Latency. The seek time is a measure (in milliseconds) of how
fast the hard drive can move its read/write heads to a desired
location. Rotational latency is a measure of the average time
(also in milliseconds) the read/write heads must wait for the
target sector on the disk to pass under them once the read/write
heads are moved to the desired target track.
Mechanical latencies are the main hindrance to higher performance
in modern Enhanced IDE (EIDE) hard drives. The time delays of
mechanical latencies are one hundred times higher than
electronic (non-mechanical) latencies associated with the
transferring of data. Therefore, reducing mechanical latencies
(a lowering of seek time and rotational latency) should be the
top consideration in improving hard drive performance.
RPM
This is the rotational speed of the media (disk), also referred
to as the spindle speed. Hard drives only spin at one constant
speed. Typical speeds are 3600 to 3880, 4500, and 5200 to 5400
revolutions per minute. The slower the RPM, the higher the
Mechanical Latencies. Disk RPM is a critical component of hard
drive performance because it directly impacts the rotational latency
and the Disk Transfer Rate explained below.
DISK TRANSFER RATE
The Disk Transfer Rate (sometimes called media rate) is the
speed at which data is transferred to and from the disk media
(actual disk platter) and is a function of the recording frequency.
Typical units are bits per second (BPS), or bytes per second.
Modern hard disks have an increasing range of Disk Transfer
Rates from the inner diameter to the outer diameter of the disk.
This is called a "zoned" recording technique.
The key media recording parameters relating to density per platter
are Tracks Per Inch (TPI) and Bits Per Inch (BPI). A track is a
circular ring around the disk. TPI is the number of these tracks
that can fit in a given area (inch). BPI defines how many bits
can be written onto one inch of a track on a disk surface. To
greatly simplify, the Disk Transfer Rate (the rate at which data
is read and written to the disk) is dependent upon the speed of
the disk (RPM) and the density of the data on the disk (BPI).
Even most modern, high-speed, 5000 RPM hard drives are generally
limited to a maximum Disk Transfer Rate of approximately 9 to 10
MB per second. This specification is critical to performance and
must be weighed carefully against such electronic latencies as
Mode 3 PIO and Mode 4 PIO host transfer rates explained below.
PC DATA HANDLING
After the data moves down the IDE cable from the drive to the host
interface, there are several factors that can affect drive
performance over which the hard drive has no control. PC Data
Handling is independent from the hard drive and very dependent
upon the CPU type and speed, the BIOS overhead (how the system
issues commands to the hard drive), speed and size of the system
RAM and RAM cache, CPU-to-memory speed, and storage subsystem
performance. PC Data Handling is also affected by the caching
methods of such software applications as SMARTDRIVE, 32-bit
disk access operating system drivers, etc.
HOST TRANSFER RATE
The speed at which the host computer can transfer data across the
IDE or EIDE interface. Processor Input/Output (PIO) modes and
Direct Memory Access (DMA) modes are defined in the ATA-2 industry
specification as follows:
Mode 3 PIO 11.1 MB/sec
Mode 4 PIO 16.6 MB/sec
Mode 1 DMA 13.3 MB/sec
Mode 2 DMA 16.6 MB/sec
Modern host computer systems usually support most of the above
modes. Faster Host Transfer Rates in the future will use multi-word
DMA modes as the industry will not support any future PIO mode
standards beyond mode 4.
The computer system manufacturer is responsible for implementing a
Host Transfer Rate that is high enough to ensure that the host
computer is not the performance bottleneck. Implementing
increasingly higher Host Transfer Rates without corresponding
increases in Disk Transfer Rates on the hard drive will not result
in increased drive performance.
Cache Buffer Size - Is Bigger Always Better ?
A Cache Buffer is similar to a water glass. When you are writing
to a hard drive, the host computer fills the glass and the disk
media empties it. If you are reading data from a hard drive, the
disk media fills the glass and the host computer empties it.
The reason that a bigger cache buffer is not always better
(or faster) is because the host computer (with Mode 4 PIO or
Mode 2 DMA capabilities) can empty or fill the glass much faster
than the hard drive can empty or fill it. When the host system can
transfer data in or out of the cache buffer faster than the media
rate, a larger buffer size becomes irrelevant because the host
system is always "waiting" for the hard drive.
Western Digital hard drives are designed with cache buffer sizes
that are matched to the Disk Transfer Rate capabilities of the
drive and the Host Transfer Rates of modern computer systems. All
of our drives are benchmarked with various cache buffer sizes to
verify that the most cost-effective and performance-effective
cache size is implemented.
Confusion Over Mode 4 and Mode 2 DMA
The Enhanced IDE program created the long-range road map for
performance enhancements which included faster disk and host
transfers, Mode 3, Mode 4, Mode 2 DMA, etc. Currently, computer
systems and hard drive controller silicon have most of the elements
needed to implement Mode 4 PIO or Mode 2 DMA (a 16.6 MB/sec Host
Transfer Rate). However, to take advantage of these performance
modes, physical drive architecture must also make some performance
improvements in the area of Mechanical Latencies and Disk Transfer
Rate (media rate) as defined earlier.
Some competitors, in their eagerness to supply a new feature, are
prematurely marketing Mode 4 and Mode 2 DMA. While their drive
controller silicon supports these modes (which is very easy and
inexpensive to implement), spindle speeds (RPM), rotational latency,
bit density, and other factors have not yet been improved (these
being very difficult and costly). The result is hard drives which
have the electronic capability to do Mode 4 and Mode 2 DMA transfer
rates, but can't take advantage of these modes due to the slower
Disk Transfer Rate of the drive.
Western Digital will not be implementing Mode 4 or Mode 2 DMA on
older drive products as the host systems into which these drives
are designed are not electrically capable of these data transfers,
nor are the Disk Transfer Rates on these drives beyond current Mode
3 capabilities. As next generation systems are introduced, they will
be paired with next generation drives. Those drives will require
and offer true Mode 4 / Mode 2 DMA capability from a total drive
architecture standpoint.
=====================================================================
AC2540/2635/2700/2850/21000/31000/31200/31600
Windows 95 Operating System Addendum
------------------------------------
The information in this addendum supersedes that supplied in Windows
95 section on pages 35 and 36 of this manual. Please refer to thos
addendum for Windows 95 questions.
Although Windows 95 is capable of recognizing the full capacity of
hard drives larger than 528 MB in systems with a translating BIOS,
some restrictions apply to systems without a translating BIOS.
For Systems With a Translating BIOS
-----------------------------------
Enter your CMOS setup and select a drive type that will recognize the
full capacity of your drive. This is usually done by selecting the
auto config drive tape. The boot partition can be set up to be as
large as the full capacity of your hard drive.
For Systems Without a Translating BIOS
--------------------------------------
Enter your CMOS setup and select a user defined drive type. Enter
these parameters: cylinders = 1024, heads = 16, sectors = 63. Your
system's total disk space will be limited to a maximum of 528MB.
If you want your system to utilize more than 528 MB of disk space,
you must use Ontrack's Disk Manager software (or a similar third-
party installation software).
Installing Windows 95 on a Hard Drive with Ontrack Disk Manager
Already Installed
---------------------------------------------------------------
The Windows 95 installation program will analyze your computer
system and install seamlessly with Ontrack Disk Manager.
Computer Systems with Windows 95 Already Installed
--------------------------------------------------
If you are installing a Western Digital hard drive and Ontrack Disk
Manager on a computer system with Windows 95 already installed, you
must install Ontrack Disk Manager as described here.
Enter your CMOS setup and select a user defined drive type. Enter
these parameters for drives with capacities over 528MB:
Cylinders = 1024, Heads = 16, Sectors = 63.
Save these changes and reboot your computer.
1. Select the Start icon from the Windows 95 main screen.
DO NOT open an MS-DOS menu from Win 95 to install Ontrack Disk
Manager.
2. Choose the Shut Down option.
3. Select Resatrt Computer in DOS mode. When your computer restarts,
you should be at the DOS prompt.
4. Install Ontrack Disk Manager.
Windows 95 will noe recognize the full capacity of your hard drive
and run in 32-bit disk access mode for optimum performance.
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