Put FAT drives on a diet, optimise CD-R backups
Put FAT drives on a diet, optimise CD-R backups
|
Tip Efficiency means getting everything you pay for. The decade-old File Allocation Table disk storage system, which worked so efficiently with 286-based PCs, torpedoes the storage efficiency of large hard disks. The culprit is the size of clusters -- the blocks that DOS and Windows use for storing data. All files get stored in one or more fixed-size clusters, and whatever bytes aren't needed in the last (and often only) cluster are wasted. Since the FAT can't divide a drive into more than 65,536 clusters, cluster size increases dramatically with drive size. Thus, where drives smaller than 128Mb use 2K clusters, a drive bigger than a gigabyte has 32K clusters (see Figure 1). With every file, directory, and Shortcut swallowing at least one cluster, your drive falls victim to cluster waste, and storage space disappears at an alarming rate. Today's FAT structure imposes another problem -- it can't support drives larger than 2Gb, although such drives will be common by year-end. So last autumn Microsoft quietly revised its FAT system to accommodate 32-bit entries. The new system, called FAT32, reserves four of its 32 bits for future purposes, so each cluster is actually identified with a 28-bit value. Using FAT32, Windows 95 accommodates drives up to 2,048Gb in size, and on smaller disks it stores files more efficiently with smaller clusters (see Figure 2). Enticing as FAT32 sounds, it's not for everyone, principally because Microsoft won't give it to you. It is available only in a new version of Windows 95 (version 950b) that vendors preinstall in new machines. Even if you could get a copy of the updated Windows 95, you couldn't just run a quick program to install the new FAT. FAT32 requires updates to all the Windows 95 disk-based utilities, such as fdisk, scandisk, and defrag, as well as the disk driver, vfat.vxd. You must repartition your hard disk and start from scratch. Moreover, your old third-party utilities such as Norton Utilities won't work under FAT32, so you must contact the publishers for updates. You can trim the cluster waste without the hassle of upgrading to FAT32. All you need is DriveSpace 3, which is included on Microsoft's Plus Utilities disk. DriveSpace 3 allocates files in sectors of 512 bytes instead of clusters, eliminating cluster overhead entirely. If you're worried about the reliability of disk compression, you can install DriveSpace 3 without compression by selecting No Compression (Fastest) from the Advanced settings menu, then installing DriveSpace. If you have a lot of small files on your system, you can save dozens of megabytes of disk space. Traditional FAT drives
Figure 1: Data clusters get bigger and less efficient as drives get bigger -- a major problem with Microsoft?s veteran File Allocation Table system
Figure 2: The revised FAT32 architecture cuts down on cluster size so you can store data much more efficiently, and it handles drives up to 2048Gb | Category: Win95 Issue: Dec 1996 Pages: 164 |
These Web pages are produced by Australian PC World © 1997 IDG Communications