[X-Unix] So what is a dmg file?

[William H. Magill]

On 22 Jan, 2004, at 10:21, Kirk McElhearn wrote:
> On 1/22/04 16:12, "Doug McNutt" <douglist at macnauchtan.com> wrote:
>> .dmg  .smi   are two Apple disk image formats that are rather new.
>>
>> How long will they be supported? Is it reasonable to use them for 
>> such things
>> as archiving on a CD-ROM?
>
> That's a good question. I wouldn't, at least not for anything that is 
> not
> OS-specific. (Apps that run on OS X would be fine, but I wouldn't put
> graphics or text files in them.) In addition, if you have one sector 
> on a CD
> that's screwed, you're liable to not be able to open the disk image 
> file at
> all.

It's all relative....

It depends on how long you expect to be able to read your CD archive.

I would expect all CD formats to be virtually unreadable in about 3-5 
years max.
Many already are.

I'm talking about the physical CD here, not even the formats of the 
data encoded on the CD.

The issue is not unlike that of the 8 inch floppy disk... not to 
mention the 5 1/4 inch version or the 3 1/2 inch one. (And I won't even 
pretend that anybody even knows what a 7 track tape format looks like, 
let alone how to read it.) Rememember, the 3.5 inch hard floppy was 
introduced in 82 or 83, only 10 years ago! And the 8 inch floppy only 
dates to about 1972!

If you want something to last to the year 3K, then print it on 
acid-free paper (not the kind you normally use in your printer) and use 
nothing less than Epson's DuraBrite inks. (They at least claim to be 
archival quality.)

Data formats are less of an issue than the physical formats -- the data 
formats can be "remembered" and the data decoded, but if you can't read 
the physical media -- all you have are pretty coasters.

For the foreseeable future ASCII TEXT, is still the only game in town. 
XML formated files contain more information in their tags than tab 
delimited files, so they are actually, probably, an improvement.

But as they say, only time will tell.

T.T.F.N.
William H. Magill
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