Formatting Hardisk

Proper setup and formatting are critical to a drive's performance and reliability. This section describes the procedures used to format a hard disk drive correctly. Use these procedures when you install a new drive in a system or immediately after you recover data from a hard disk that has been exhibiting problems.

The three major steps in the formatting process for a hard disk drive subsystem are as follows:

  1. Low-level formatting

  2. Partitioning

  3. High-level formatting

Low-Level Formatting

All new hard disk drives are low-level formatted by the manufacturer, and you do not have to perform another LLF before you install the drive. In fact, under normal circumstances, you should not ever have to perform a low-level format on an ATA or SCSI drive.

Most manufacturers no longer recommend that you low-level format any ATA type drive. This recommendation has been the source of some myths about ATA. Many people say, for example, that you can't perform a low-level format on an ATA drive, and that if you do, you will destroy the drive.

This statement is untrue! What can happen with some of the earliest ATA drives is that you might lose the optimal head and cylinder skew factors that were set by the manufacturer for the drive, as well as the map of drive defects. This can have a negative effect on the drive's performance, but you can still reliably use the drive.

Note that all drives that internally use a zoned recording (where there is a variable number of sectors per track internally) are immune to any problems due to low-level formatting because the actual sector marks can't be rewritten. This includes pretty much all modern ATA drives made in the last 10 years.

However, sometimes you must perform a low-level format on an ATA or a SCSI drive. The following sections discuss the software you can use to do this.

SCSI Low-Level Format Software

SCSI drives also come preformatted, and unless there is a problem with the drive, you will not have to perform this operation yourself. If you do want to low-level format a SCSI drive, you must use the LLF program provided by the manufacturer of the SCSI host adapter.

The designs of these devices vary enough that a register-level program can work only if it is tailored to the individual controller. Fortunately, all SCSI host adapters include low-level format software, either in the host adapter's BIOS or in a separate disk-based program.

The interface to the SCSI drive is through the host adapter. SCSI is a standard, but no true standards exist for what a host adapter is supposed to look like. This means that any formatting or configuration software is specific to a particular host adapter.

ATA Low-Level Format Software

ATA drive manufacturers have defined and standardized extensions to the original WD1002/1003 hard disk controller card to AT-bus (ISA) interface, which is known as the ATA (AT Attachment) interface. The ATA specification provides for vendor-unique commands, which are manufacturer proprietary extensions to the standard.

To prevent improper low-level formatting, many of these ATA drives have special codes that must be sent to the drive to unlock the format routines. These codes vary among manufacturers.

If possible, you should obtain LLF and defect management software from the drive manufacturer; this software usually is specific to that manufacturer's products and often is model specific. Check the brand and model number of your hard disk to determine the utility program you need.

Most ATA drives are protected from any alteration to the skew factors or defect map erasure because they are always in a translated mode internally.

Zoned bit recording drives are always under translation and are fully protected. Most ATA drives have a custom command set that must be used in the format process; the standard format commands defined by the ATA specification usually do not work, especially with intelligent or zoned bit recording ATA drives.

Without the proper manufacturer-specific format commands, you can't perform the defect management by the manufacturer-specified method, in which bad sectors often can be spared. Most manufacturers supply low-level format programs for their drives. Here are a few examples:

You should try the manufacturer-specific format programs first. They are free, can often work at a lower level, and can handle defects in ways that the more generic ones can't. If formatting software is not available from your drive's manufacturer, I recommend Disk Manager by Ontrack and the Micro-Scope program by Micro 2000.

Another excellent, inexpensive, general-purpose PC hardware diagnostic that includes low-level format capability is the Hitachi (formerly IBM) Drive Fitness Test (DFT) program. The Drive Fitness Test program works on non-Hitachi and non-IBM drives as well and performs a detailed and thorough test of your hard drive.

I recommend this as one of the best general-purpose drive test programs on the market because it can do a fairly thorough test in nondestructive mode. It performs an LLF (destructive) only on IBM- and Hitachi-brand drives. You can download DFT from the Hitachi site listed previously.

Nondestructive Formatters General-purpose, BIOS-level, nondestructive formatters, such as Calibrate (older Symantec Norton Utilities) and SpinRite (Gibson Research), are not recommended in most situations in which a real LLF is required.

These programs have several limitations and problems that decrease their effectiveness; in some cases, they can even cause problems with the way defects are handled on a drive. These programs attempt to perform a track-by-track LLF by using BIOS functions, while backing up and restoring the track data as they go.

These programs do not actually perform a complete LLF because they do not even try to low-level format the first track (Cylinder 0, Head 0) due to problems with some controller types that store hidden information on the first track. These programs also do not perform defect mapping in the way standard LLF programs do, and they even can remove the carefully applied sector header defect marks during a proper LLF.

This situation potentially enables data to be stored in sectors that originally were marked defective and might actually void the manufacturer's warranty on some drives. Another problem is that these programs work only on drives that have already been formatted and can format only drives that are formattable through BIOS functions.

A true LLF program bypasses the system BIOS and sends commands directly to the disk controller hardware. For this reason, many LLF programs are specific to the disk controller hardware for which they are designed.

Having a single format program that will run on all types of controllers is virtually impossible. Many hard drives have been incorrectly diagnosed as being defective because the wrong format program was used and the program did not operate properly.