Some Basic Stuff You Need To Know--ok !!

Some info you'll need to Understand Your Hard-Drive:
This Page with get you started in understanding of the Hard-Drive. Even though we'll be addressing the IDE-at system, all drives Mfg.'s have to deal with Windows-95 FAT. If you need help with FAT explained or FDISK or FORMAT or Partition Magic 3 for More Information, use the e-mail or Comment Page. Thanks.

The short story about EIDE & SCSI comparison:
The gap between SCSI and IDE is closing so the additional cost of the SCSI makes it almost unfavorable to buy. Dollar for dollar, the answer is not really about transfer rate and it's RPM but the overall system. A good motherboard, 512kb pipeline memory and good ram will be more efficient and it will make your hard drive work better than choosing between scsi or IDE controller drive. Personally, I like IDE hard drives and keep the registry clean. A clean windows registry will speed up the system. However, a disk spends most of its time moving the arm to the right location and waiting for the data to rotate around to the point where it can be read or written. A SCSI controller can have all of its disks moving into position while one disk is actively transferring data.

Ultra DMA (or ATA) drives transfer data at twice the rate of EIDE4, and are replacing IDE drives. Ultra DMA hard drives are direct replacements for IDE drives, but motherboards with TX chipsets are required to take advantage of this feature. If you do not have a TX motherboard, Ultra DMA drives will work automatically as IDE, or EIDE drives without any settings during installation. The drives will check for a motherboard with a TX chipset, and if no TX chipset is on board, will run at the highest speed the motherboard is capable of. These Ultra DMA drives are usually priced within $5.00 of IDE, and may be less since they are produced at a lower cost than the older drives.

A User's View Point:
Let's take a look at what happens when you retrieve data from a hard disk drive. When you issue a command to open an existing file, the application program you're running prompts you to enter the name of the file to open. It then passes the file name to the operating system, which determines where the file is located on the disk drive - the head number, cylinder, and sector identification. The operating system transfers this information to the disk controller, which drives an actuator motor connected to the actuator arm to position the heads over the right track. As the disk rotates, the appropriate head reads the address of each sector on the track. When the desired sector appears under the read/write head, the entire contents of the sector containing the necessary data are read into a special, ultra-fast memory, called cache, on the drive's PCB. Then, the disk drive interface chip sends the necessary information to the computer's main memory. (in short-more cache buffer, better performance). Storing data on a hard drive is a similar process to retrieving data, only reversed. The host computer operating system is responsible for remembering the addresses for each file on the disk and which sectors are available for new data. If the file you want to store is large - for example, (NOTE: I put this in for my friend SLIM), a 10 MB CAD/CAM drawing - the operating system instructs the controller where to begin writing information to the disk. The controller moves the read/write heads to the appropriate track and writing begins. When the first track is full, the heads write to the same track on successive platter surfaces. If still more track capacity is required to store all the data, the head moves to the next available track with sufficient contiguous space and writes the data there. Although an extraordinary amount of care and effort goes into making the platters for hard disk drives, it is not economically feasible to manufacture 100 percent defect-free media. Therefore, all modern hard drives have a defect management strategy built into the disk controller to provide defect-free operation in the field. Defect management involves setting aside some spare sectors on each disk surface to replace a limited number of defective sectors. At the end of the manufacturing process, the entire disk surface is scanned for defects and the disk controller stores a map of their locations. When the operating system requests that information be written to one of the bad sectors, the disk controller transparently maps it to one of the spares. The disk controller continuously updates the defect map.

NOTE: a word about (IDE);
EIDE is a marketing program started by Western Digital to promote certain ATA-2 features including ATAPI. WD has encouraged other product vendors to mark their products as "EIDE compatible" or "EIDE capable".

Unlike humans, who use a 10-digit, decimal system for everyday computation, digital computers and most other electronic equipment rely on a 2-digit, binary system. Using the binary system, all data - letters, numbers, and other objects - are represented by a series of binary digits called "bits." Consisting only of 0s and 1s representing on or off switch positions, bits are recorded on a data storage medium, such as the magnetic coating on the platters of a computer's hard drive. By combining individual data bits into larger, 8-bit groupings called "bytes," computers encode data for computing. For example, the letter "B" is encoded as "01000010" in the most widely used method for representing alphanumeric characters for computer storage, display, and printing.

To fully appreciate the vital role mass data storage devices play in storing and retrieving information, you need to understand the basics of computer systems. A computer consists of both hardware and software components working together to help you accomplish your tasks. At the most basic level, computers perform computations. They rapidly add, subtract, divide, and multiply numbers that represent encoded data (letters, numbers, charts, images, colors, etc.). We work with this data everyday when we use application software such as word processors, spreadsheets, and graphics packages.

Let's take a look at what happens when you retrieve data from a hard disk drive. When you issue a command to open an existing file, the application program you're running prompts you to enter the name of the file to open. It then passes the file name to the operating system, which determines where the file is located on the disk drive - the head number, cylinder, and sector identification. The operating system transfers this information to the disk controller, which drives an actuator motor connected to the actuator arm to position the heads over the right track. As the disk rotates, the appropriate head reads the address of each sector on the track. When the desired sector appears under the read/write head, the entire contents of the sector containing the necessary data are read into a special, ultra-fast memory, called cache, on the drive's PCB. Then, the disk drive interface chip sends the necessary information to the computer's main memory.

Are there supposed to be bad sectors on the drive?
No. but all modern drives support error management, which completely hides any bad sectors that may be on the disk off factory. Even a single bad sector is sufficient grounds to return the drive under warranty. If you want to continue using it, the drive should be viewed with the utmost suspicion.

Western Digital has a utility wdat_ide.exe that can hide grown bad sectors on many Caviar disks. There is one exception. Under rare circumstances, use of bad (too fast) timing by the disk adapter can cause bad sectors on a disk. This type of error can be fixed simply by writing fresh data to these sectors, as there is no actual media defect.

How Data is Organized on a Hard Disk Drive:
The surface of the drive platter is organized with coordinates, much like a map. Data is stored in concentric tracks on the surfaces of each platter. (A platter has two sides, and thus, two data recording surfaces.) A typical disk drive can have more than 2,000 tracks per inch (TPI) on its recording surface. A cylinder describes the group of all tracks located at a given head position across all platters. To allow for easier access to data, each track is divided into individually addressable sectors. The process of organizing the disk surface into tracks and sectors is called formatting, and almost all hard disk drives today come preformatted by the manufacturer. The process of formatting a hard drive applies addressing data to the platter's surface. In almost all systems, including PCs and Macintoshes, sectors typically contain 512 bytes of user data plus addressing information used by the drive electronics (although some proprietary systems use other sector lengths). The disk drive controller, which resides on the drive's PCB, uses the formatting information and addresses - much like a tourist uses a city map - to guide data into and out of a specific location on the hard drive. Without formatting instructions, neither the controller nor the operating system would know where to store data or how to retrieve it. In earlier hard drive designs, the number of sectors per track was fixed and, because the outer tracks on a platter have a larger circumference than the inner tracks, space on the outer tracks was wasted. The number of sectors that would fit on the innermost track constrained the number of sectors per track for the entire platter.

However, many of today's advanced drives use a formatting technique called Multiple Zone Recording to pack more data onto the surface of the disk. Multiple Zone Recording allows the number of sectors per track to be adjusted so more sectors are stored on the larger, outer tracks. By dividing the outer tracks into more sectors, data can be packed uniformly throughout the surface of a platter, disk surface is used more efficiently, and higher capacities can be achieved with fewer platters. The number of sectors per track on a typical 3.5-inch disk ranges from 60 to 120 under a Multiple Zone Recording scheme. Not only is effective storage capacity increased by as much as 25 percent with Multiple Zone Recording, but the disk-to-buffer transfer rate also is boosted. With more bytes per track, data in the outer zones is read at a faster rate. Multiple Zone Recording on 2.5-inch disk drive products. Read/Write Heads:Skimming the Surface Read/write heads are the single most costly component of a hard disk drive, and their characteristics have a great impact on drive design and performance. Despite their expense, the head's basic design and objective are relatively simple: a head is a piece of magnetic material, formed almost in the shape of a "C" with a small opening or gap. A coil of wire is wound around this core to construct an electromagnet. In writing to the disk, current flowing through the coil creates a magnetic field across the gap that magnetizes the disk coating layer under the head. In reading from the disk, the read/write head senses an electronic current pulse through the coil when the gap passes over a flux reversal on the disk.

As technology increases, bits are packed more densely, and the space required to store a bit shrinks. At the same time, the tiny size of the stored data bit causes the signal produced by the head when reading the bit to become weaker and harder to read. As a result, the fundamental challenge in packing bits closer together is finding a way to fly the heads closer to the media to increase the amplitude of the signal. The hard disk drive industry has made great strides on this front. In 1973, flying heights averaged 17 microinches. Today's heads fly at just three microinches, with 2- to 2.5-microinch flying heights expected soon. And, in the not too distant future, read/write heads might even make contact with the media, enabling data to be packed even more densely on the platter surface but offering the additional challenge of eliminating added wear on the disk media and read/write heads.

Typically, a drive head must settle lateral movement of the actuator, it must stop before a read and write operation can begin and it must settle before a write can occur. Drive Mfg.'s firmware with read-on arrival lets the drive start a normal read operation before settling is complete and if an error occurs it is corrected via advanced ECC algorithms. In Auto transfer ASIC technology, an interrupt occurs in an IDE system at each sector (512 bytes) of data transferred and this takes away from primary work. A drive Mfg.'s firmware can significantly reduce the number of interrupts during processing of the I/O request allowing the transfer of multiple sectors of data per interrupt and is similar to DMA or fast multiword use.

Regardless of the physical capacity of the disk drive itself, with DOS prior to 1989, there was a 32 MB partition limitation due to FAT fixed 512 byte cluster size. In 1985, the 16-bit FAT can in to support larger partitions with the use of larger clusters. Then there was the issue of the FAT and VFAT systems 2.1 GB barrier where of the maximum of 65,536 clusters. Fat clusters vary in size according to the size of the partition. This means for DOS, Windows and Windows 95 users currently cannot address a disk logical partition larger than 2.1 GB because larger drives require multiple partitions to provide storage.

NOTE: Windows NT and OS/2 users are not affected.

The increasing demand for drives with larger capacities means and requires more powerful error correction schemes called (on-the-fly) error correction to save millisecond burst errors of which takes 1 full disc revolution or (app. 13ns) and without it, the rates decrease output. This means that the sequencer continues running unless more than one error occurs in the same sector. In this case, a more rigorous correction algorithm enables correction of double-burst errors of up to 3 bytes and a unrecoverable error rate of 1 error in 10-14 bits read, and the head must settle it.

I have tried many different scenario's and you can realize a very small increase in speed (of which is almost undetectable unless you run some bench tests) but it isn't worth the trouble. One of the many scenario's I tried is below, so try it if you must.

(1) One way or the other (FDISK or PM 3), make a (100mb) partition. After you have created the partition, go to Control Panel, click on System, click the Performance tab, click on Virtual Memory. You'll see a drop box arrow listing the available partitions. Just choose the 100mb. You can also choose the size of the file. I choose -(0) & +(100) and re-boot.

(2) It's where you want Windows to operate: Again--make a partition. 120mb for W95 & 200mb if you have W95b or W98.
Re-install your Windows in this partition, Partition Magic 3 makes it easy.

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