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Re: File Backups

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Ah, Bill, the debate is on - am I glad to have you back!!!!!!!!
I agree with you that nothing is full-proof and because of this you should
always protect yourself with backups of your work. That aside, lets discuss
compression and swap files.
First, it is not necessary for a Windows 95 swap file to reside on an
uncompressed drive. I have had mine on a compressed drive for three years -
until recently. The only reason I switched it to an uncompressed drive (and
this was before my reported crash) was that the uncompressed drive had
little activity to fragment my swap file. Therefore it was less likely to
become fragmented and slow over the course of time.
Windows 95 swap files are not the same as they were in 3.1. Mainly, they are
dynamic - expanding and contracting as needed by the operating system. This
creates a problem only when you become limited on available disk space
(compressed or uncompressed). You will notice when this happens that the
famous Blue Screen Exception errors begin to occur frequently as do General
Protection Fault errors.
Since the release of Microsoft Plus and the change over from Doublespace (a
MS algorithm) to Stacker (a proprietary compression scheme) compression has
become very stable. I have yet to encounter problems with a compressed drive
that is not easily solved with either Scandisk or Nortons Disk Doctor.
Microsoft has a built-in protection scheme that shuts you down and warns you
of impending danger when a corruption is found in the compressed drive. This
has happened a number of times on my system and is usually attributed to
shuting my machine off without closing down the system in the proper
manner - usually from lockup or GPF errors. Although since I removed all of
the beta software and reinstalled my system a few weeks ago, crashes such as
this occur less and less frequently.
Once the system shuts down with knowledge of a corruption in the compression
scheme, Windows keeps reminding you to run Scandisk. You can over-ride this
feature, but you would be courting diseaster.
I can't agree with Bill about compression. The only disadvantage that I have
enountered is a slight loss of performance due to compression. However, this
can be adjusted by changing the level of compression for files used more
often than others. Drivespace allows you to specify Ultra Compression or
Standard Compression depending upon how often a file is accessed. You can
also specify no compression for certain file types.
Why do I support compression? We use it every day. Each time we zip a file
down we take the chance that compression routine will corrupt our work, but
when was the last time that PKZip distroyed a file. Compression has been the
market for well over five years now and has proven to be safe. I have lost
more data to cluster and sector errors than to corrupted compression files.
One other advantage to compression files is that they don't fragment as much
as uncompressed files. This is because the area of the hard drive that is
reserved for compression is a finite space and all files created and
rewritten to the drive are done within the same space. Therefore, file
fragments don't occur at one end of the drive and another at the spindle.

One point that Bill made that is absolutly correct is that you do not gain
more compression by trying to write a zipped file to a compressed drive. The
two technologies are essentially the same and there is no additional
savings. This is similar to trying to remove blank spaces from a letter.
There are a finite number of blank spaces and you can only remove them once.
I tested this recently by compressing a 100mb Zip disk and trying to add
185Mb or Zipped files to the disk. Won't work. I was only able to get 100Mb
or Zipped files to the disk since they were already compressed.

Finally, the "Stacker" Technology that Microsoft was forced to adopt due to
the lawsuit that occured when Microsoft introduced DoubleSpace turned out to
be far more stable than MS's scheme. Stacker uses an LHZ compression scheme
that is similar to PKZIp. In fact, you can find add-ons to WinZip that will
read and compress using the same LHZ technology. Remember, there are various
compression schemes - Zip, LHZ, JPG (a graphic compression scheme), ARC
(which was out there before ZIP and may have been the child of Ward
Christenson for those who might remember the name for the old CPM days
called Squeeze I believe), LHA and ARJ.  There are a couple of programs on
the market for those of you who do not want to compress drives. These
programs will compress and uncompress programs and files on the fly. I'm not
crazy about these since most require intermediate steps. Hey, even tape
backup programs use compression techniques to squeeze 2 gigs of data on 1
gig tapes.
We use compression software all the time without thinking about it, tape
backups, Zip drives, WinZip and more. Therefore, why be scared of Drivespace
compression when we store our data in compressed format on tape backups.

Dennis
-----Original Message-----
From: Bill Allen <BAllenSE(--nospam--at)mail-gw2.pacbell.net>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Monday, January 05, 1998 7:42 PM
Subject: Re: File Backups


>While I'm not as sharp about OS's as Dennis is, I would still be concerned
>about Drivespace. You never get something for nothing. I also wouldn't
think
>that the Windows swap file issue matters since the swap file does not
reside
>on the compressed drive. The problem is that, when you try to copy a file
>onto
>either a "normal" floppy or Zip disk and there is no room, you get a simple
>"disk
>is full" message. This is not the case with a mounted drive (at least when
I
>did it
>on an old version of Stacker). The thing crashed and I was up until 5:00 am
>trying
>to recover data. Even MS tech. support has told me that a drive set up for
>Drive-
>space is not as reliable as a standard drive. For those of you more
>adventurous
>than me, go ahead. Otherwise, buy more Zip disks.
>
>Regards,
>Bill