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Liam
18-03-2003, 09:58 PM
Thanks for previus reply. May I rephrase the question - what is the difference between an archive and a folder? does an archive have properties different from a folder?

tweak\'e
18-03-2003, 11:01 PM
i think you are thinking of compressing a folder or data for storage. for eg use winzip/winrar/ace to compress data so it uses less space and is easy to send to other people.

Murray P
18-03-2003, 11:07 PM
Hi

Archive = File attribute: Read Only. Hidden. Archive.

Cheers

Murray P

Graham L
19-03-2003, 02:09 PM
A Folder (directory) holds individual files. The space used for each file is allocated in cluster-size units. On average, there is about half a cluster of space wasted for each file. Small files can be horribly wasteful.

An Archive -- the computer meaning of the word dates from the 70s with the tar (tape archive) programme of Unix -- saves space by storing <filename><size of file><file><filename><size><file> ... in one big contiguous lump. This was necessary for tape storage of backups, because of the physical layout of data on tapes. The gaps between blocks and individual files wasted lots of space. Of course the files aren't as fast to access as individual files, but that's not really a problem for backup applications. The space saving makes up for it.

Usually archives are compressed, to save even more spacve. Zip is a compression utility which can make and store archives. Rar is a later one. Unix used compress (of course, :D), Linus/BSD use gzip or bzip:the files often have an "extension" of .tar.Z or .tar.gz or tar.bz or .tgZ, .tgz ...

The "Archive" bit of the DOS file attributes is set when a file is created or changed. It can be turned off by backup programmes to show that the file has been saved, and need not be saved again in incremental backup systems. (Xcopy can manipulate this bit too, so you can have copy/move operations depending on the state of the Archive bit.).

Susan B
19-03-2003, 02:45 PM
I have often wondered about the Archive attribute as well but never got around to researching it. :-)


> The "Archive" bit of the DOS file attributes is set when a file is created or changed. It can be turned off by backup programmes to show that the file has been saved, and need not be saved again in incremental backup systems.

From what you are saying, Graham, I take it that the archive attribute is utilised by backup programs? Would it also be utilised by defrag to move unused files to the back of the hard drive?

So how does Windows know when to actually archive a file? Does it have a set number of days before a file is archived?

I suppose you are going to send me to Google now, aren't you? :p

Graham L
19-03-2003, 02:58 PM
Do "xcopy /?". That will give you an option something like "copy all files with the archive bit set and clear the bit after the copy". That lets you, say, set the bit (with "attribute +a *.*", say, or selectively) then "xcopy *.* a: /that option " . When a floppy fills, you just put in another floppy and repeat the command. It will carry on from where it got to. The file which filled the first floppy won't have the bit cleared, because the copy wasn't successful, so it will be properly copied. (Of course, any medium can be used). This works nicely.

Defrag (if it moves rarely used files) would use something like a "last access date", which is probably part of the later Windows directory structure. That's been in real operating systems for decades. :D
The archive bit just indicates that the file has not been backed up since it was modified.

Susan B
19-03-2003, 03:37 PM
Thanks Graham. I have archived your replies for future reference. :D