WINDOWS 95 - HARD DISK EFFICIENCY ( AND DUAL BOOTING)


INTRODUCTION

This document discusses hard disk efficiency under Windows 95 in respect of number of partitions and cluster size. It then suggest ways of improving storage efficiency, and for achieving multiple booting.


CLUSTER SIZE

For systems not using the latest 32 bit FAT system (which is incompatible with MS-DOS), the cluster size is at least one 64,000th of the partition size. By default when installed , Win95 sets up only one partition.  For modern hard disks, necessary for Win95, the partition size is over 1Gb.  This means that the cluster size is at least 16Kb.  Table 1 shows the relationship between partition size and cluster size.

		Partition		Cluster
		(Gb)			(Kb)

		0.5			8
		1			16
		2			32
		4			64

If your hard disk exceeds the partition values, then the next cluster size is required.  A 1.3Gb partition will have 32Kb cluster, and a 2.5Gb partition will have 64Kb cluster.

The cluster size is the smallest increment of storage available on the partition.  Small files of only a few bytes will still require one cluster for storage.

Although Win95 has a number of large files, particularly .EXE files, it also has a significant number of small files.  In particular every entry in the Start Menu consists of a small file of a few hundred bytes.  A typical Start Menu may consist of 166 files and 32 directories, with around 70Kb of data.  On a smallish partition with 8Kb clusters, this data will occupy over 1.6 Mb of disk space, with over 90% of this space wasted. On a 1.3Gb partition, this will rise to 6.5Mb, and 13Mb on a 2.5Gb partition.

If an Internet program such as Internet explorer is used, its cache will also contain a large number of small files. Again the disk storage could easily be in excess of ten times the total of the file sizes.

On a typical Win95 installation with nearly 5,000 files, over one half of these will be 8192 bytes or less.  The code/data content of these small files will be around 5Mb, and occupy 20Mb on 0.5Gb, 80Mb on 1.3Gb, 160Mb on 2.5Gb.  The combined files total around 300Mb code/data, with 26Mb wasted when stored in a 0.5Gb partition.  For any cluster size, the wasted space per file will be around half the cluster size - 5000 files in 8Kb clusters gives 20Mb wasted.  On 2.5Gb partition with 64Kb clusters there would be 160Mb wasted.


PARTITIONS

To minimise cluster size, one should have as many partitions as possible.  A standard partition table will support up to 4 partitions.  However, partitioning a disk into four equal parts may well not be ideal.

Consider the case of a 2.5 Gb hard disk.  If this is split into four equal partitions, each partition will be over 0.6 Gb, giving a cluster size of 16Kb.  Dividing it into three  0.5Gb and one 1Gb will reduce the cluster size to 8Kb on the three smaller partitions. Reducing the partition size by 0.1Gb and halving the cluster size will save around 26Mb on 300Mb of files.

Using FDISK enables one bootable primary partition, and three extended partitions to be created.  It is not possible to accurately set a partition size to the maximum permissible for a given cluster size.

Third party partition utilities, such as PartitionMagic, do allow more accurate sizing of partitions, and also permit multiple primary partitions.  Multiple primary partitions are useful if more than one operating system is to be run, e.g Win95 and MS-DOS 6.2x.  Note that some other operating systems may reject a partition table with moreh than one primary partition.  Once more that one primary partition has been created, it is then possible to boot from whichever one is set active by FDisk or similar utility.

With an upgrade version of Windows 95 it is possible to boot to Win95 or the previous version of MS-DOS from a single partition.  This is NOT possible with the latest (1996) OEM version.  When both systems are co-existant, it is easy to run MS-DOS utilities from the previous version that are unaware of long file names that will seriously harm Windows 95 directories and files.  For instance running a directory sort utility on the root directory will destroy the long name of the directoy "Program Files" that is essential to Win95.

When running a previous version of MS-DOS, it is safer to run it from a separate partition, and hide the Win95 partition, either by using the SUBST command, or an advanced partition utility such as PartitionMagic


EXAMPLE

Installing a new 2.1Gb hard disk with an existing 820Mb hard disk, and make the system dual bootable.  Requires MS-DOS, Windows 95 and PartitionMagic.

The existing 820Mb hard disk has already be used under MS-DOS, and has been partitioned in to two halves using FDISK.  One partition is primary and the second is extended. The cluster size of each 420Mb partition is 8Kb.

1) Create bootable MS-DOS system floppy, including FDISK and FORMAT
2) Create a floppy with the essential PartionMagic files.
3) Disconnect existing 820Mb hard disk and install new 2.1Gb hard disk.
4) Boot from MS-DOS floppy, and run FDISK.  Set the first partition as primary, active, with a size of 520Mb. Then FORMAT C: /S to create a fully bootable hard disk.
5) Remove floppy and boot from hard disk.
6) Run PartitionMagic from the floppy, and check that the cluster size is currently 16Kb from Options/Info.
7) From PartitionMagic reduce the cluster size to 8Kb from Advanced/Resize.  The partition should now be about 509Mb.
8) From PartitionMagic create a new FAT partition, unhidden, initially 520Mb, then resize to 8Kb clusters.  This will become drive D:
9) From PartitionMagic create a new FAT partition, unhidden,  initially 520Mb, then resize to 8Kb clusters.  This will become drive E:
10) From PartitionMagic create a new FAT partition, unhidden, using the remaining disk space.  This will become drive F:
11) Return to MS-DOS. Apply FORMAT /S to D:, E: and F:
12) Reconnect the old hard drive as the secondary hard disk, and reboot.  The drive mappings should change to the following:
	C:	HD 1 C:
	D:	HD 2 C:
	E:	HD 2 D:
	F:	HD 1 D:
	G:	HD 1 E:
	H:	HD 1 F:
13) Install Windows 95 on C:
14) From Win95 shell out to MS-DOS and run FDISK. Set Drive 1 Partition 2 as active, and reboot.  The drive mappings should change to the following:
	C:	F: HD 1 D:
	D:	D: HD 2 C:
	E:	E: HD 2 D:
	F:	C: HD 1 C:
	G:	G: HD 1 E:
	H:	H: HD 1 F:
Drives C: and F: will be reversed.
15) Install MS-DOS onto the current C: (partition 2).
16) To hide the Windows 95 partition from MD-DOS, include the line SUBST F: C:\ in the MS-DOS AUTOEXEC.BAT.  Henceforth MS-DOS will appear on drive F: for both MS-DOS and Windows 95.
