A new group of utilities is appearing on Macintoshes around you. Once it was the rage to archive files by grouping them into a single file and compressing that group for storage or transmission via telecommunications. Famous in this task are StuffIt Deluxe and Compactor Pro. Later, file-by-file compression on the desktop appeared in such INITs as DiskDoubler and SuperDisk. Now we are faced with compression of all (or most) files on your hard disk as a way of life!
What’s Going On?
More Disk Space is a system level (System 6 or 7) compression utility that will give you more available disk space by compressing all the files on your disk. These files are not intended for archiving or transmission; the objective is simply smaller files. Every attempt has been made to provide this compression in a transparent manner. That is, the user can’t tell anything is happening except that there is more space available. Desktop publishing applications can preview file contents and all applications recognize their files normally.
Installation is a little odd. You must boot your system from the disk provided and use the Install option from the More Disk Space program. The disks whirl and the work is done after you enter your name, company, and serial number in the usual way. Then you can re-boot normally, run the More Disk Space application, select More Disk Space from the MDS menu and go out for dinner. When you return everything looks the same except your available disk space has grown.
More Disk Space is not quite an INIT in the normal sense. To be sure that it’s code is available even if you boot while hold down the shift key, More Disk Space installs itself before any INITs. You can’t disable More Disk Space! This technique is used by Apple’s System 7 Tune-Up and even by some viruses. We are cutting a new path in the forest of compatibility issues; if we have many programs installing themselves before INITs, how will they interact with each other? Conflicts among INITs are so numerous as to be common place.
Whenever your Macintosh has been idle for a time, More Disk Space will run and compress any new files. As you open and close files, More Disk Space decompresses and re-compresses those files. Applications are compressed as well and will sometimes launch faster than in their expanded state.
From the additional Finder menu you can selectively compress or expand files, as well as create auto-expanding archives for storage or transmission. There is also the ability to create auto-segmenting files for files too large to fit on a single floppy disk.
How Does It All Work?
I installed More Disk Space on my machine and have been using it in manual mode for the last couple of weeks. I have not yet turned More Disk Space loose on my whole hard disk in automatic mode — call me cautious (more on that later). I’ve tried a few experiments with speed and efficiency of compression on files and the effects of compression on applications. Transparency of operation is important to me, also; I have been watching for problems in that area too.
Completing the installation, I re-booted and set up the program options to my taste. Configuring is easy, and many options are provided. Let’s touch on the significant items.
More Disk Space can compress applications, documents, and replace duplicate applications with an alias. Many choices are available for basic operations—recompression of files from within applications when they are saved; adding a menu to the Finder to allow operation from the desktop; run in the background and begin operation after a set time (must be a startup application).
Other options allow files to be automatically decompressed when copied from the Finder (good if you want to exchange files with other people without More Disk Space), or allow applications to be compressed in such a way that they will still run on Macintoshes without More Disk Space. You can set the size to be used by auto-segmenting files.
An interesting ability of More Disk Space is the conversion from SuperDisk, DiskDoubler, and StuffIt format files to More Disk Space format. I don’t have these utilities so I have been unable to experiment with this.
Except For
Nothing is as simple as we would like and file compression is no exception. More Disk Space maintains an exception list for files and applications that are not to be compressed. Several come pre-excepted, but you are on your own to figure out what applications don’t like to find themselves or their files compressed.
Notable exceptions preassigned are MicroPhone II, Diskfit, Norton Backup, HFS Backup, Redux, SUM Backup, and FastBack (all backup utilities); and Red Ryder, White Knight, Versaterm, Z-Term (all telecommunications applications). Several file types are also excluded by default including font and desk accessory suitcases, StuffIt archives, and several others I could not identify.
Adding applications is easy. Click the add button and select from the dialog box. Adding documents is the same; just click on an example of the type to be excluded.
Aladdin System’s beta release of StuffIt Deluxe 3.0 conflicts with More Disk Space. Aladdin claims that there is a bug in More Disk Space; they say it “patches high-level file manager calls, but fails to patch at least one low-level call that StuffIt and many other applications use.” Alysis says that the problem is with StuffIt Deluxe, and they will offer a patch to Aladdin’s program to solve this conflict when it is released. Since the new version of StuffIt will offer the same online compression as More Disk Space, this all sounds like noisy competition rather than real technical disagreement. Still, why would Alysis create a patch for StuffIt if it’s all Aladdin’s problem?
How Do They Do It?
To create their magic, Alysis claims to have reverse engineered Apple’s own resource compression techniques. Apple uses this compression in their System, Finder, and TeachText applications to reduce their size. Virus checkers are not confused by this compressed format (does anyone know if DiskDoubler format confuses them?), and the Finder displays the actual compressed size of the file (that may be a minus for some, more on that later). No other software is required to use these compressed applications, and Alysis is licensing this technology to other developers to use on their applications.
Does It Work?
That’s the big question for everyone. Let me tell you about my experiences. The first thing I was interested in was how much compression can More Disk Space provide. This would seem to be an important measure of a file compressor. With respect to speed of compression, I have taken a radically new approach (for me). I’ve ignored the time to compress a file because More Disk Space is meant to work in the background. Compression is therefore something the user will rarely see, and I’ve focused on time to open compressed documents and launch compressed applications.
To examine compressed efficiency, I took several common document types (Excel, FreeHand, MacWrite, Claris CAD, and HyperCard) and compressed them. Then I took several applications (MacWrite II, FreeHand, and White Knight) and compressed them, too. The results were impressive. Documents were reduced to an average of 40% of their original size while applications were down to 55%! So far, so good.
To see if the documents were OK when compressed, I opened each by double-clicking from the desktop. All the documents retained their proper icons and launched the correct application. Excel launched properly but showed odd progress as the document opened; at one point saying it was 256% complete before reporting 100%. Everything else seemed to behave.
To get a feel for the speed of compression for documents, I measured the difference in time to open a normal document versus its compressed counterpart. You would think that time must be spent to decompress these files as they are opened. I thought that too, but my tests showed that files opened in the same amount of time even if they were compressed and sometimes less. The results were mixed on absolute times, but even opening at the same speed is great — faster opening is a bonus.
I had the same results when timing the launching of compressed applications. Results were mixed, but launch time was the same or faster when compressed. I’m afraid I have no explanation other than a great compression technique and implementation. All reason would suggest that opening compressed files and applications should take longer than the uncompressed versions to account for the time to decompress. Live and learn.
Anyone who bought the Disk of the Month for May can testify about the convenience of More Disk Space’s self-extracting archive format. This format takes a file or folder and compresses it in such a way that it “knows” how to decompress itself. Just double-click on it. The overhead for the self-decompression ranges from about 5.5KB to 8KB depending on the document contents. Auto-segmenting documents are convenient if the compressed auto-extracting archive will still not fit on a floppy disk. These files not only “know” how to expand themselves, they can also join the segmented parts.
I don’t have a network, so I can’t test More Disk Space’s ability to speed up network access. The idea is that More Disk Space can automatically compress files when they arrive on the server. General network performance should improve due to the smaller files to be transferred.
A unique capability of More Disk Space is its ability to compress applications in such a way that they can be used in the compressed format even on Macintoshes without More Disk Space. Things seemed to work pretty well for the most part. Programs launched as normal except for MacWrite II.
MacWrite II gave a warning that it had been corrupted when the transportable compressed version was run. Compression without the transportable option on does not cause a problem. More Disk Space warned that this would happen, so perhaps MacWrite computes a checksum on itself and checks that when run. The compressed version has been modified so MacWrite complains. If you continue through the complaint, it seems to work fine.
More Testing
There is room for more testing and experimentation. More Disk Space and the other on-line compression utilities are complicated additions to the normal system. How do they behave with backup utilities? How about low level file editors? Can disk repair applications such as Norton Disk Doctor properly recognize and diagnose these compressed files? Will an INIT conflict disable More Disk Space or render its compressed files unusable? I don’t have the resources nor the expertise to completely answer these questions. I’ll be waiting for the “big time” outfits such as MacUser and MacWeek to review More Disk Space also.
Should You Use It?
Should you use More Disk Space? Should you use any such on-line compression utility? Ultimately, each user must answer that question for himself. What are the long-term ramifications of compression of all the files on your hard disk? If you must boot from a floppy, More Disk Space must be installed for you to have access to anything on your hard disk!
As I’ve already said, there are more tests to be run before this issue is clear. I, for one, plan to use More Disk Space as a individual file compressor and archive collection creator for a while. I’ll compress a few applications and large files (with good backups) and use them for awhile and look for signs of strange behavior. Perhaps confidence in this new technology will come with time.
Gripes
More Disk Space can be too transparent. There is no way to tell if a particular file has been compressed or not. The file icon remains the same and the Finder’s Get Info… command gives you the actual file size, but is that the compressed size? Who can tell? This is bad and can cause confusion. Alysis promises to add the ability to determine the expanded file size in their next version.
I would like more technical documentation in the little user’s manual. Maybe a separate reference manual would be better. There is no discussion of how More Disk Space does its magic. The manual says there’s a temporary file created while you edit a momentarily expanded file in case of a problem. Does it create a temporary file while compressing so the data could be recovered in the event of a power failure or system crash? (I know, Macintosh never crashes.)
The manual should also discuss compressed format conversions. There’s little there other than to tell you to check the boxes. Do you need to have the other utilities installed? Does More Disk Space use the StuffIt Deluxe compression engine? How are we to be sure the translation is complete, without exception? I’d just like to know more about the behind-the-scenes activity.
There is no notice given if a file is not compressed! If a file type is given as an exception and a file of that type selected for compression, More Disk Space displays the normal dialog box and process bar but does not compress the file. The same is true if application compression is turned off but you try to compress one anyway.
More Disk Space will create a self-extracting archive which is larger than the original file! I created an auto-expanding file from a 622 byte file and got a 8,614 byte file in return. And, in another case of too little feedback, got no warning message.
At The End Of The Day
Alysis has been very cooperative in my dealings with them, and they seem to be a company attempting to provide a safe, effective solution to the compression problems we all have. They came on the scene a little late behind the better-known DiskDoubler and StuffIt. My experience with More Disk Space has been basically good, although there is room for improvement. I found the older SuperDisk to be faster than its competition several months ago, but the interface was poor.
More Disk Space is a better program than SuperDisk and does more, too. I like the fact that on-line compression and desktop manual compression are combined in the same program unlike the DiskDoubler AutoDoubler pair. At a mail order price of about $45, More Disk Space is worth your trying. I love the ability to compress and expand from the desktop. With regard to automatic compression of everything, as I’ve said, until this technology in general has had a little more time to mature, I’m going slowly. Look for a follow-up article then.
The article above is reprinted from Mac Monitor, the newsletter of The Savannah Macintosh Users Group. It may be reprinted in a single issue of newsletters published by non-profit user groups. Payment shall consist of a single issue of the newsletter in which the article appears, sent to the following address:
