Increasing Hard Drive Capacity

One of the ways of increasing the hard drive capacity is selecting optimal cluster size. All information stored on the hard drive is presented in the form of files. Disk space for storing these files, in turn, is allocated in so-called clusters. Clusters comprise a number of sectors of a predetermined size.

The size of a cluster usually ranges from 2 to 32 KB. The size of each cluster depends on the disk partition size. Every file, depending on its length, takes up one or more clusters. Even if the size of the file is less than that of the cluster, that file will nonetheless take up the entire cluster.

For instance, when cluster size is 32 KB, a bat-file of a few dozen bytes will take up all 32 KB of disk space. We can estimate that, on average, every file takes up about half of its last cluster. The remainder of the cluster cannot be assigned for another file.

Consequently, on the disk there will be a good number of clusters whose space is not fully used, which means wasted disk space (so-called slack space) and loss in capacity. This loss is approximately equal to the number of files on the disk, multiplied by half of the cluster size.

For example, if you have 10,000 files on one disk, and a cluster size of 32 KB, you are wasting about 160 MB [10,000 × (32 KB/2) = 160 MB]. In the case of a logical drive that, for example, takes up all of the space of a Seagate 1.08 GB hard drive that has 1,030 MB of informational space with 20,000 files, the slack space comes to approximately 320 MB, or 31% of the hard drive's capacity.

If, however, the cluster size were reduced to 16 KB, the slack space on that same drive with the same number of files would be reduced to 160 MB, which is only 16% of the hard drive's capacity. Partitioning the hard disk into several logical disks decreases both the cluster size and the slack space.

Methods of improving disk efficiency by reducing wasted space are:

  • Archiving files. Usually, the first candidates for archiving are large sets of rarely used files.

  • Partitioning the hard drive into logical drives of smaller size.

  • Installing and using disk compression utilities: Stacker, DriveSpace, and so on, which organize their own structure of virtual disks.

  • Migrating to other file systems, such as HPFS/NTFS or FAT32, which organize disk space more efficiently than FAT16.

The maximum number of clusters allowed for a disk is 65,536. Consequently, the larger the disk, the larger the cluster. Partitioning the hard drive into smaller logical sections — logical drives — can decrease the size of the clusters.

Thus, to improve the efficiency of using the hard disk space, it's advised that you divide the large hard disk into several logical disks. Notice that contrary to popular opinion, partitioning the HDD does not change the performance of the disk subsystem. Rather, it allows you to reduce the slack space by reducing cluster size.

Another method of improving the efficiency of disk space usage is to compress the disk with a special program such as DriveSpace 3. This program implements a special method of data storage that reduces wasted disk space to practically zero.

Using the disk compression program DriveSpace 3 allows you to significantly reduce the amount of wasted disk space related to cluster size. Many users compress their disks with zero compression so as not to waste free space on the disk, and so that they won't notice the performance degradation.

For large disks it is possible to use FAT32 — a newer file system — which operates using relatively small clusters. However, FAT32 is only supported by relatively new versions of Windows operating systems, namely, Windows 95 OSR2 and later versions.

Developed in 1981, FAT (File Allocation Table) became the first file system for PCs running MS-DOS and earlier Windows versions (Windows 3.1). FAT is very widespread and guarantees a high operating speed. However, up until recently, FAT not been able to support disks larger than 2 GB.

At present, Windows 9x includes an improved file system of the FAT type called FAT 32, which supports disks up to 2 TB (1 TB = 1024 GB = 1024 × 1024 MB = 1024 × 1024 × 1024 = KB). Compared with the FAT16, FAT32 uses disk space more efficiently. This is due to the fact that FAT32 uses relatively small clusters.

The file system FAT32 is completely compatible with all computers and all programs for earlier versions of the MS-DOS and Windows operating systems. However, some problems may arise while using certain disk utilities. Older versions of disk defragmentation, compression, and management utilities won't work correctly with FAT32-formatted disks.

Disk maintenance utilities included with Windows 95 OSR2, such as ScanDisk, Backup, and Disk Defragmenter can fully support disks with FAT32. However, you cannot compress disks with FAT32 using DriveSpace. FAT32-formatted disks can't be accessed in an original Windows 95 version.

Disks that use FAT32 are accessible in Windows 95 OSR2 (Windows 95 4.00.1111), Windows 98, Windows ME, and Windows 2000. However, in Windows OSR2 you can work with FAT32 in MS-DOS mode. Network access is also possible, and the remote computer need not support FAT 32.

Some programs may incorrectly determine the amount of free space on a FAT32 disk if they have not been specifically developed for the new file system. Older programs cannot correctly determine the size of disk partitions larger than 2 GB.

Therefore, any information on free or used disk space or on the total disk capacity that is provided by such programs is misleading. Windows 95 version 4.00.950B includes new APIs, which allow you to deal with the given problem.

The task of determining whether the disk is FAT32-formatted is relatively simple. Double-click the My Computer icon, right-click the disk you wish to check, then select Properties from the menu. In the General dialog, the disk type will be displayed in the Type field.

After migration to the FAT32 file system, overall performance generally remains the same. However, in some cases you may notice slight performance degradation. When you boot Windows 9x in MS-DOS mode or in Windows safe mode, the disks formatted for use may work significantly slower.

To solve this problem, you should run the disk-caching program SmartDrive when booting in MS-DOS mode. To format an existing or newly added disk to use FAT32, use the Fdisk system utility. This program is intended for creating and deleting partitions on the hard drive. There are two types of partitions — primary and extended.

A primary partition is formatted for a particular file system and is assigned a drive letter. An extended partition, on the other hand, can be divided into one or more logical drives. In contrast to primary partitions, an extended partition is not assigned a drive letter.

If the partition size is more than 512 MB, Fdisk will prompt you to use the large disk format. Therefore, in the new partitions with sizes exceeding 512 GB, FAT32 will be installed. If FAT32 is not used, the size of newly created partitions will be limited to 2 GB.

In order to use all the available disk space of a large hard disk you'll need many logical disks. After the creation of these sections, the computer should be rebooted in order to format the new logical disks.

One of the disadvantages of IDE/EIDE hard drives is their limited capacity. The standard BIOS imposes a limit on the number of cylinders (1024) and sectors (63). Thus, the capacity of the hard disk is limited to 504 MB. This problem is usually solved using special drivers released to go with each series of hard drives.

Consider, for example, the Dynamic Drive Overlay v.6.03 driver released by Ontrack Computer Systems, Inc. This driver is installed using the Disk Manager program from the same company. These tools are used with Western Digital hard drives.

Another example is the EZ-DRIVE V2.03S driver from Micro House International, often used with Seagate hard drives. In order to standardize the installation of larger hard drives, a new method of translating the cylinder, head, and sector specifications of the drive into addresses that can be used by an enhanced BIOS was developed — LBA (Logical Block Addressing).

The sector address is translated in the form of a linear, 28-digit sector number, which is transformed for the hard drive into the proper number of cylinders/heads/sectors. To work in LBA mode, it has to be supported by both the hard drive and its driver (or BIOS).

When working through BIOS, the hard drive will have 63 sectors, the number of heads equal to a power of 2 — upto 256, and the necessary number of cylinders.