Road to Mac OS X Leopard: Time Machine - Page 3

Originally Posted by damomurf

And that is where you need to be careful. Other than the amazing visual experience offered by Time Machine and the integration with individual applications, rsync is *very* much capable of achieving *exactly* the same backup strategy. Tiger already supports hard links as discussed in the article and rsync supports syncing content using hard links to avoid storing redundant copies of the same file. Sure, it's not going to be as user friendly, but it would actually work.



With rsync and hard links there would be no "restore" as such, you'd just change to a folder on your backup drive that corresponds to a backup date. That folder would appear as a full backup.

I agree that rsync isn't as good an option as Time Machine appears to be from a usability point of view - but lets not forget that it is actually capable of achieving a very similar result in terms of file storage and retrieval.

Originally Posted by GregAlexander

One of the rumour sites spoke about Apple's portable user logins. In essence, a remote device holds all of the user data including passwords & some (or all) user files. The idea was that you could go up to any Mac's user-login screen, plug in an external device (eg iPod) and your username would appear in the user-login screen. You login with your own password, apps, files... everything.

Is it possible that a TIme Machine backup (onto a 160GB iPod, for instance) could ALSO be a portable home directory for any mac you plug into?

Originally Posted by deep

Seriously, you guys rock for posting these in-depth articles. Kudos to you and your team

Originally Posted by Booga

This is a good background article, but it misses the point of Time Machine, I think. Backing up files is old news, and I'm sure Time Machine does it as well as anyone. The real magic of Time Machine, though, is information retrieval. It's something that Shadow Copy and rsync can't hope to do.

In a traditional file backup solution, if you discover one missing record in your Address Book, you'd have to go get all your incremental backups, restore each file in turn, look for the record, and if you find it export it manually, then restore the current version and import it.

With Time Machine, you just search back through time using the same search field you do normally. It will go back in time and find the first instance of the search criteria and allow you to restore just that record to the present. THAT is revolutionary. The rest is just another implementation of an old concept.

Originally Posted by khyros

...snip...
b) This is about the hourly/weekly backups.

For example:

Oct 12 7pm : newly created File A is backed up to TM
Oct 12 8pm : file A was previously (7.30pm) delted so it doesn't appear on this hourly backup.
Oct 13 12am: daily backup from Oct 12 is backed up to TM. It doesn't contain file A, but file A is backed up in hourly 7pm from oct 12.

Now... a few days later, it comes the time to delete hourly backups... how does TM manage to keep file A in the TM pool for me to recover at a later time?

Originally Posted by bxs6408

TM will keep your File A around for a period of 24 hr and then it will be expunged as you correctly surmised. However, if the Trash has not been emptied File A will remain in the Trash until such time you empty the Trash. Once the Trash is emptied then File A will be gone.

Originally Posted by khyros

This sounds all so weird and wrong to me ...

Originally Posted by bxs6408

TM will restore a complete system backup and it will be bootable afterwards. Pop in the DVD Installer disc, select the Volume you wish to restore to, select the complete TM backup you want to restore from, wait for it to complete the restore operation and then you will have a bootable system once again. Works just fine, easy to do and without any real fuss.

Originally Posted by Quarky

If the Mac which has created the Time Machine Backup fails and comes to the End Of It's Life.
Can you attach another Mac to that external hard drive and access those backup files without doing a system restore?
Paul

Originally Posted by bobandris

Barry,

Will TM do the same for your "BootCamp" Volume? No one seems to know. If so, I'm sold!

Bob

Originally Posted by bxs6408

Interesting question. I don't know for sure - sorry.

However, even though TM, by default, excludes all volumes except the boot volume it is possible to change this. Thus if the Boot Camp Volume were named let say 'BC-HD' then user would remove BC-HD from the TM's exclusion list and allow TM to backup BC-HD.

At some later point if BC-HD failed, got corrupted suddenly or whatever, then the TM browser can be used to restore the BC-HD volume to a past time point the user felt BC-HD was in good shape such as 1 day ago or 4 days ago or 1 month ago.

Originally Posted by bxs6408

TM will keep your File A around for a period of 24 hr and then it will be expunged as you correctly surmised. However, if the Trash has not been emptied File A will remain in the Trash until such time you empty the Trash. Once the Trash is emptied then File A will be gone.

Originally Posted by AppleInsider

The flip side is that some users get a backup system set in place that appears to be working, and are lulled into a false sense of security, unaware that it isn't. The faults might lie with unreliable back backup media, procedures not being carried out correctly, or the system not capturing new data it was not originally designed to protect.

Originally Posted by GregAlexander

Any regular backup... if it was done at midnight daily... would miss a file that was created at 7am, and then deleted at 7pm.

However, TM will backup every hour... so you're safe there (unless created and deleted within the same hour). For a file that is months old, it's not going to keep every version of the same file... and I guess if you only have a file on your computer for 15 days, then you'll lose the file.

THis would happen on regular backup schedules too.

Originally Posted by Abster2core

No way. If you create a new file, i.e., A and it is back up with Time Machine one hour and deleted within the next hour, the original back up of A is still there on the back up drive.

Best you read this article again and visit Apple's web site. A lot of questions continue to be raised and they are well answered on the two sites. Postulating on what Time Machine can or can not do by some of the meanderings here, only confuse the understanding.

Originally Posted by khyros

apple hasn't clarified my doubts that's why I ask here for those of you who have actually tried TM.

hourly backups are only kept for a period of time (a week?) then those are tosed and only weekly and then monthly backups are kept; all according to what i've read here and in the guide.

if file A is in the hourly backup but not on the mac's drive when the weekly/monthly backup is done, ultimately file A will be lost when hourly backups are deleted by Time Machine.

or so it seems and that's why I think it's weird...

Originally Posted by Abster2core

This is so wrong! Unless of course your are doing a full back up and tossing the previous one each time.

Originally Posted by khyros

I think it's weird...

Originally Posted by infobhan

Does anyone have an idea of how TM would interact with Parallels? It would seem problematic, because whenever Parallels is active, you'd be making small changes to the virtual drive for your Parallels machine, meaning that a multi-GB file would need to be copied over every hour. Is this how it works?

Originally Posted by khyros

apple hasn't clarified my doubts that's why I ask here for those of you who have actually tried TM.

hourly backups are only kept for a period of time (a week?) then those are tosed and only weekly and then monthly backups are kept; all according to what i've read here and in the guide.

if file A is in the hourly backup but not on the mac's drive when the weekly/monthly backup is done, ultimately file A will be lost when hourly backups are deleted by Time Machine.

or so it seems and that's why I think it's weird...

Originally Posted by bxs6408

At this time TM is tightly coupled to Address Book, Mail and iPhoto. All three employ data bases so losing an Address/contact, an Email or a photo in an Album/Event is not like deleting/losing a file. This is why TM can magically restore items for Address Book, Mail and iPhoto.

Deleting files is handled by TM as has been explained already.

Changing a byte in a data base will cause that data base to get backed up on the next TM snapshot. Deleting a byte in a data base will also have the same effect.

It will be wise to exclude the Downloads folder from backups (especially for large downloads that could takes several hours) as TM snapshots will pickup these files (or parts that have been downloaded) multiple times. Plus, typically the downloaded files get moved from the Downloads folder to other places and will subsequently get picked up again by the next TM snapshot.

If Parallels churns data in its virtual volume it will get picked every time by the TM snapshots. It will be the users choice to exclude this from TM snapshots as they wish.

TM is not your regular/traditional backup. It's a compromise between the traditional base+incremental backups and the easy data restoration, system restorations and simplified data restoration for some Applications such as Address Book, iPhoto and Mail along with keeping the amount of data backed up to be useful and of reasonable size. It could be that Apple adds others to be tightly coupled to TM. Third party Apps can also do the same thing with their Apps as Apple has done with their three Apps.

Apple wants to have TM be easy to use by Joe user who quite likely today perform no backups at all. Joe user doesn't want to understand the intricacies of backups. Just plug a 500gig HD in and turn TM on and then forget about it until the time arises to retrieve some lost data, be it a file, photo, contact, Email and even the whole complete system.

It will be of interest to see how this TM feature grows over time.

Originally Posted by bobandris

Barry,

Will TM do the same for your "BootCamp" Volume? No one seems to know. If so, I'm sold!

Bob

Originally Posted by bxs6408

At this time TM is tightly coupled to Address Book, Mail and iPhoto. All three employ data bases so losing an Address/contact, an Email or a photo in an Album/Event is not like deleting/losing a file. This is why TM can magically restore items for Address Book, Mail and iPhoto.

Deleting files is handled by TM as has been explained already.

Changing a byte in a data base will cause that data base to get backed up on the next TM snapshot. Deleting a byte in a data base will also have the same effect.

It will be wise to exclude the Downloads folder from backups (especially for large downloads that could takes several hours) as TM snapshots will pickup these files (or parts that have been downloaded) multiple times. Plus, typically the downloaded files get moved from the Downloads folder to other places and will subsequently get picked up again by the next TM snapshot.

If Parallels churns data in its virtual volume it will get picked every time by the TM snapshots. It will be the users choice to exclude this from TM snapshots as they wish.

TM is not your regular/traditional backup. It's a compromise between the traditional base+incremental backups and the easy data restoration, system restorations and simplified data restoration for some Applications such as Address Book, iPhoto and Mail along with keeping the amount of data backed up to be useful and of reasonable size. It could be that Apple adds others to be tightly coupled to TM. Third party Apps can also do the same thing with their Apps as Apple has done with their three Apps.

Apple wants to have TM be easy to use by Joe user who quite likely today perform no backups at all. Joe user doesn't want to understand the intricacies of backups. Just plug a 500gig HD in and turn TM on and then forget about it until the time arises to retrieve some lost data, be it a file, photo, contact, Email and even the whole complete system.

It will be of interest to see how this TM feature grows over time.

Originally Posted by Abster2core

Stop it!

Time Machine backs up a file. It remains on your designated external drive until you physically remove it.

Delete the file from you computer deliberately, by accident or by foul play and you simply restore the file from the backup when you want to.

Revise the file and on the next backup, Time Machine will attach the change. If the file has been removed from you computer in the meantime, Time Machine does nothing to the backup. There is nothing to see, check or update.

As such, you can literally and purposely, accidently delete and/or fry your drive and use Time Machine to restore you machine to any time in history that has been backed up to your designated external drive.

Think about it. It is called Time Machine. And for a reason.

Originally Posted by jehrler

The question is what does it mean to have hourly/daily backups eliminated.

1) All files that ever existed on that day with every version of any file that changed.
2) The last version of all files that ever existed on that day?
3) Just the files that existed when the last backup ran before the purge?

Similar issues/questions arise for the weekly and monthly purges.

Originally Posted by jehrler

The question is what does it mean to have hourly/daily backups eliminated.…The question I have is when one goes back in Time to this day that has been purged of the hourlies, what do I see and what is available to restore?

1) All files that ever existed on that day with every version of any file that changed.
2) The last version of all files that ever existed on that day?
3) Just the files that existed when the last backup ran before the purge?

Similar issues/questions arise for the weekly and monthly purges.

Originally Posted by Abster2core

Stop it!

Time Machine backs up a file. It remains on your designated external drive until you physically remove it.

Delete the file from you computer deliberately, by accident or by foul play and you simply restore the file from the backup when you want to.

Revise the file and on the next backup, Time Machine will attach the change. If the file has been removed from you computer in the meantime, Time Machine does nothing to the backup. There is nothing to see, check or update.

As such, you can literally and purposely, accidently delete and/or fry your drive and use Time Machine to restore you machine to any time in history that has been backed up to your designated external drive.

Think about it. It is called Time Machine. And for a reason.

Originally Posted by melgross

What I'm seeing here is a lot of speculation about how things are done at various levels in the OS, and I'm wondering if people here really know what they're talking about

Someone, set up a drive. All you have to do is to look at what is being saved. This could have been done a month ago. Once you see what is being done, then you will know for certain, and all of this disagreement can end.

Originally Posted by melgross

I don't see what the big deal is here folks.

The OS version every developer has now is the one that will be VERY close to the one released.

Instead of all of this silly arguing back and forth, simply take a look.

Are you all saying that while you are all willing to argue this to death without knowing anything, none of you actually have a TimeMachine drive set up and working?

If not, then nothing said here has been of any value whatsoever.

Someone, set up a drive. All you have to do is to look at what is being saved. This could have been done a month ago. Once you see what is being done, then you will know for certain, and all of this disagreement can end.

Many of the arguments we have here can't easily be proven one way or the other, so they go on for pages. But this one shouldn't even be happening. Either it does what Apple says, or it doesn't. It can be easily found out.

If someone is going to say that it doesn't work yet, so they can't find out, then it's so late in the process it won't be available in the release either.

So, will someone please give correct information from an actual working system?

Thank you.

Originally Posted by GregAlexander

Actually, what you're seeing is people here looking at all the information we have on "how it works", in contrast to the marketing description, and then asking about a hole that seems to be there in a reasonably unique situation.

For almost any regular users usage, it will work "as advertised".

[edit: The actual article says the deletion "maintains a complete, extensive set of backups that balance out the demands for backup frequency versus disk space."]

On a related note and as I said before, deleting files because they're in the backup is a bad idea - create an archive instead. It's similar to users who store their read emails in the trash because it's convenient.



Good idea!

Could someone with Leopard:
1) create File1 at noon, and delete it 1.5hrs later. Check it's in Time Machine.
2) Create File2 at 2pm, and delete it 1.5 hrs later. Check its in Time machine.
3) Wait till the hourly backups are deleted (2 days later, to be safe?)
4) see if both File1 and File2 are in the daily backup....

Originally Posted by Abster2core

First of all, forget or disregard "How Time Machine works"

Best to read Apple's Time Machine info (http://www.apple.com/macosx/leopard/...memachine.html) and view the linked Demo.

I really don't know of a simpler way to describe its functionality.

Just remember that using Time Machine as directed, i.e., attaching an external drive, assigning it to Time Machine and keeping it live and connected everytime you turn on your computer, you'll be able to restore virtually every snapshot of your computer as you create, revise or delete files on your computer.

If you look at the Demo carefully, you'll see Time Machine move from one day to the next at the same time of day, i.e., "6:33 PM." However, if you notice the list of files sorted by "Last Used Date," it appears to be a Spotlight "Result" listing every "Italian Design" file which have been created or altered within minutes of each other and beyond. Are the 'Documents' as listed the same? I don't know. It just seems that Time Machine could be quite granular in its backup process.

Whatever, I feel quite confident that I will be able to back up my entire computer, frag all those files I hesitate to permanently delete and keep my machine lean and meanand a lot easier and faster than I do now. More important, at anytime, I can travel back in time and restore files that I would normally have to search through hundreds of DAT tapes, CD's or DVDs now.