Feature Request: alternate data streams (ADS)

[Wolf]

Yes, I know - this is quite a challenge!
This feature of NTFS (ADS) has been around for quite some time without anybody (except M$) making much use of it. But I wouldn't bet on this staying that way.
In fact I am using it myself to attach comments to files (and folder) that do not get lost when I copy or move them (to other NTFS partitions).
But if you really come to think of it, a binary comparison is probably what most people would want to use to ensure that two file are identical. They would then take it for granted that these files are the same and possibly delete one of them. Fact is, they have only compared the file's default stream, and may be deleting some important information in the ADS.
Yes - you are warned by the OS, if you move the file to a FAT32 partition - but not if you simply delete it.

AFAIK there is currently no comparison tool to compare ADS along with the default stream, or even to warn the user that a file has ADS attached!
This is not a good situation. I would like to see BC -as the IMO leading software for that purpose- tackle that problem. Or is this on the developers' agenda already?

[Zoë]

Hi Wolf,

Thanks for the suggestion. Out of curiousity, what kind of interaction do you see BC doing for this? Do you want them shown in the directory compare as separate entities, or just a + or something to indicate that they're there? It sounds like you want to view them in the file viewer as well.

Alternate data streams have been on my radar for a while, but they're currently a pretty low priority. Getting ADS information means opening every file in every directory you're comparing, which can add significant overhead if you're comparing across a network. I did some quick tests displaying a directory comparison (no content comparisons). The best case, listing a local directory, was 40% slower, and accessing my local computer using a UNC path was 300-400% slower. I can only imagine the kind of overhead it would add in a WAN environment.

On the flip side, I believe that OS X resource forks are similar to ADSs, and they're much more common. If/when we do an OS X port, I can see us supporting resource forks, and if we come up with a good solution there it should be easy to expand it on Windows. Hard links/junction points are basically in the same boat, except they're waiting for progress in our Linux build.

In any case, any specific suggestions you have are also welcome. It's more likely they'll get added if we have a good idea what our customers want out of it.

[Wolf]

Hi Craig and thanks for jumping in here!
I have read your comments about ADS, Resource forks and Junctions with great interest.
Good news!

Out of curiousity, what kind of interaction do you see BC doing for this? Do you want them shown in the directory compare as separate entities, or just a + or something to indicate that they're there? It sounds like you want to view them in the file viewer as well.

Being just your typical user, I want it all of course
No, kidding aside, I'd foremost want to see some kind of alert that could tell me if (when)
one of the files has attached ADS and the other has not.
That alone would already be extremely helpful.
If it could show me their names or sizes (like ZoneIdentifier or SummaryInformation) I could already tell whether I'd care about that sort of info.
At this point an opportunitiy to invoke an external viewer would surely be welcome.
(I recently had contact to Rekenwonder
http://www.rekenwonder.com/streamexplorer.htm
and there is a chance that they may modifiy their viewer to accept a path and/or filename as parameter.)
As a second step it would be nice to have an option to actually compare those ADS -- only
in such cases, where files appear to be identical so far.
After all, that is what I often use BC for; find identical files - truly and totally identical ones.

I am quite willing to accept any speed loss for the benefit of this.
As we are speaking of options that can be enabled or disabled, speed should not be a concern to anybody. Nobody in his right mind would make a comparison including ADS the default action, given your statistics.
But if you want 100% reliable compatison, BC should be offering it.
I could imagine it being an entry in BC''s context menu for subdirs ("include ADS in here and below)".

I cannot comment on OS X through lack of own experience, but I'm happy to learn that there is something related in the pipeline.

In any case, any specific suggestions you have are also welcome. It's more likely they'll get added if we have a good idea what our customers want out of it.

I had initially made a search for ADS across the forums, and was surprised to not get any hits.
It looks like the feature is not so commonly used or known, though it can be quite useful.
Maybe with Windows 7 there'll be more. Or perhaps others will join in here to give us their views on the matter?