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Implementing Leopard features for Vista?
Carol Haynes:
So to get something close to Time machine, one needs to mount drives for each snapshot (TM does hourly (24), then daily (~29), then weekly (...) snapshots). I suspect one will run out of drive letters before long?
-nontroppo (November 08, 2007, 05:46 AM)
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I suspect one will run out of disc space on a Mac if it does hourly snapshots - Apple aren't exactly generous with their supplied hard discs anyway.
Seriously though there is no reason why you couldn't do hourly snapshots with Acronis TrueImage - and periodically mount and index the images.
I am not quiote sure what TM indexes consist of - are they really like a desktop search of document contents or is it just file names? If it is indexing 24 snapshots a day it must make a huge performance hit both in terms of CPU usage and disc space usage !!!
Maybe my other idea with FileHamster (or another file versioning utility like Adobes Version Cue) would be a better approach on windows. If you set it to watch whole drives then you can say keep only the n most recent revisions of files and then every file is instantly version controlled over the number of revisions you require. If you have a decent desktop search tool like Copernic then all of those revisions would also be continuously updated in the index and it would all be pretty transparent.
If you just want a system to be able to roll back just set up a scheduled incremental or differential imaging pattern but there is no real need to keep the contents indexed on system files etc.
nontroppo:
I am not quiote sure what TM indexes consist of - are they really like a desktop search of document contents or is it just file names? If it is indexing 24 snapshots a day it must make a huge performance hit both in terms of CPU usage and disc space usage !!!-Carol Haynes (November 08, 2007, 07:19 AM)
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The Ars Technica and Prince McLean review delves into the details. But the basic point is that the filesystem transparently monitors file system events anyway. Any app can use these notifications (instead of forcibly watching for chages, just register to receive updates). This arrived with Spotlight, but has been made a public API in Leopard. This gives a low overhead mechanism[1] to know what to backup without specifically scanning the FS. It will ignore temp files and the like already, but if you want you can manually micromanage what is backup up IIUC. It uses something called multi-links (like a hard-link):
http://www.appleinsider.com/articles/07/10/12/road_to_mac_os_x_leopard_time_machine.html&page=3
to keep each versioned system complete but not use up more space than needed. Every day, it drops the previous day's hourly backups. Every week it drops the previous week's daily backups. Thus is balances the fact that you probably want to restore something you deleted quite recently with the possibility of still keeping older versions around.
Maybe my other idea with FileHamster (or another file versioning utility like Adobes Version Cue) would be a better approach on windows.-Carol Haynes (November 08, 2007, 07:19 AM)
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Well, I love Filehamster and depend on it in Windows. But it isn't a versioned recovery tool, it is a personal versioning system. I suspect part of the role of TM can be served by it, though I'm not quite sure how comfortably it would integrate with a desktop search.
Again I suggest that, for most users, the interface does matter. Hobbling together 3 or more utilities, each with a different UI, not servicing the purpose, is not the same experience as a tool built for the purpose. Unifying disaster recovery, versioned filing and desktop search throughout the OS is a usability win. That will reduce the discrepancy between those who know they should back up with those who do.
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[1] I use a program that builds lists of events, FSEventer to see changes to the whole FS in real time, the kernel overhead of that app tapping into FSEvents is not measurable.
Carol Haynes:
I used to use Powerquest's V2iProtector (which was their corporate imaging solution and image compatible with Drive Image). Unfortunately is was discontinued when Symantec bought out Powerquest. V2iP had a similar setup in that there was a low level service that monitored disk activity to speed up incremental image creation. It wasn't 100% there by the time the product was ditched but it was a similar idea to what you describe.
TM sounds interesting and a neat solution (assuming it works consistently and doesn't get screwed up when something else in the system goes wrong). I get the impression that a combination of incremental and differential backups using something like Acronis TrueImage (there are plenty of other apps that could probably do this too such as Genie Backup Manager if you want to monitor very specific or multiple file/folder sets) would effectively give the same rollback function. You can use the built in scheduler in TrueImage to specify hourly incremental backups and only retain 24 increments so that the oldest is dumped after day 1 on a rolling program. You can also specify a daily differential backup which would act as a daily rollup of all the increments - and again only retain 7 old differential images. Periodically you would need to start with a new base image - but I'd guess TM would need to occasionally move day 0 too otherwise the system would fill up within a few weeks.
MrCrispy:
TimeMachine will not backup to the same disk, like VSS will do. Nor will it backup over the network, or to anything that is not a dedicated disk or is not HFS+. In that respect it is more limited but that really doesn't matter. Its so simple to setup and use that for many users, its the first viable backup scheme.
If I have a baseline snapshot in TrueImage, and then 10 incrementals, I would expect to mount one snapshot in a single drive letter and then be able to browse my entire drive. This is what VSS and TimeMachine both allow you to do. The difference, and its a key one, is that with Vista you have to know where to start - the exact folder or file, and then you can browse. With TimeMachine, its all interactive and you can choose to browse anywhere. Its possible because of the special hardlink support for directories that Apple implemented. This is also possible in Linux today with a number of programs such as rsync, rsnapshot and ext3cow. But of course none of them are as usable as the Windows/OSX versions.
To me TimeMachine is a moderatley impressive backend (hardlink for directories, fsevents) coupled with a fantastic frontend (the flashy UI, integration with AddressBook and Spotlight). I still believe that technically the backend in Windows is superior and I see no reason not to have that frontend too.
I don't think backup programs should use propietary file formats. Keep them as files, compress them transparently (if on Windows) and that way other apps and OS services can use them. You know what, I feel sufficiently strongly about this that I may start writing my own :)
nontroppo:
MrCrispy: 8) :Thmbsup:
As a challenge, I will state (tongue-in-cheek but in the spirit of my above posts) that you will be unable to easily write a TM clone using the Win32 API. And I'd genuinely love to be proved wrong ;)
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