How does time machine handle deleted files

I've recently grown into a 1.5TB external hard drive where I back up my iMac through Time Machine. I'm a photography hobbyist who does a lot of processing work on my photos in Photoshop, therefore I'm regularly generating sizable data to back up.
My question is, using some hypothetical numbers:
Pretend I create 50GB of new data by importing a lot of photos onto my iMac, then Time Machine does it's thing before I can decide what photos I want to keep or trash. I later go back and edit my photo catalog and decide I only want to keep 1/2 of photos from that previous import, reducing that data to only 25GB. Will Time Machine keep those old pictures on my external drive, even though I deleted them from my iMac? Will Time Machine ever recognize I threw away those files, assume I don't want them, and overwrite them? Or is Time Machine going to keep using my my external drive to back up everything until I used up all of the externals space?
Message was edited by: Michael Streubert

Understanding how TM deletes things can be difficult, but I'll try to summarize it:
-TM will back up your system every hour.
-After 24 hours, TM will delete all but one of the 24 previous hourly backups. The one it decides to keep will become your "daily" backup. You have no control over which of those 24 backups it will select to keep as the daily.
-After 30 days, TM will start to delete the old daily backups too. It will keep 4 of the last 30 backups, one for each week.
-After your TM disk fills up, it will start to delete old backups to make room for new ones.
So, after you delete them from your main HD, the length of time that they kept on the TM drive can vary. If the files existed for only a few hours, then there is a good chance that they will be purged from the backups the following day. Or they might be kept for weeks or months, depending on if TM decided to keep those backups as the daily or weekly. It's kind of a crap shoot.
If the files existed on your main hard drive for between one and seven days, then they will remain on your TM backup drive for at least a month. After that they are at risk of being purged out.
If the files existed for more than a week, they will stay on your TM drive until it fills up. After that, they are at risk of being deleted.
I hope this helps.

Similar Messages

How does Time Machine handle alias files on the backup volume?

I have been trying to find some info on how Time Machine handles alias files on the backup volume, but can't find anything on that topic. Neither here in this discussion or at the Apple support pages.
My concern is if an alias file on the backup volume is backed up »as is«, or if it is resolved and the original file is backed up? The last would be most annoying as this will make the size of the backup much larger.
Even though I do not know of folders having been renamed (which will cause that folder and all its content to be backed up again) Time Machine often backs up a surprisingly large amount of data, so I suspect that alias files could be resolved.
Any info on this will be appreciated.

Alias files are NOT followed, AFAIK.
For more info on how TM works, see this ars technica review.
Good luck!
Message was edited by: joshz

How does Time Machine handle large files?

I'm relatively new at the whole Time Capsule / Time Machine process and have learned that large files (eg aperture library) are backed up each time there is a change and this can lead to the TC filling up quicker than normal.
How does this work with daily and weekly backups?
For example, if my aperture library is, say 1Gb and I import a load of photos from my camera and this goes up to 2Gb. I've learned that I should disable time machine while I'm in Aperture (or at least before 10.6...not sure now). So given I've done that, imported the files to Aperture but want to edit them later and ultimately move them into iPhoto to keep the Aperture album small.
When I turn back on Time Machine, the next hourly backup will know the library has changed and will back it up, this will go on until a day backup has been taken - this deletes the 24 hourly backups? or does it merge them?
If I then do the editing the following week, then export the photos and the library is now back to 1Gb again....backed up hourly/daily/weekly etc what am I left with??
Do I have an original, the 2GB version and the new 1Gb version...ie 4Gb......is there a cunning way I can work to change the files within a week so only one of the changes is in the backup?

Orpheus999 wrote:
When I turn back on Time Machine, the next hourly backup will know the library has changed and will back it up, this will go on until a day backup has been taken - this deletes the 24 hourly backups? or does it merge them?
The Time Machine panel of System Preferences says this:
Time Machine keeps
- Hourly backup for the past 24 hours
- Daily backups for the past month
- Weekly backups until your backup disk is full
Each time Time Machine runs it creates what appears to be an entirely new backup set, although it does this in a way that doesn't require it to copy files that have already been copied. So merging isn't necessary. Another effect of how it operates is that each unique version of a file (as opposed to packages of files) only exists on the backup volume once.
According to the contents of my Time Machine backup file, hourly backups are literally kept for 24 hours, not until the next "daily" backup. For a "daily" backup, it seems to keep the oldest "hourly" backup for a day.
If I then do the editing the following week, then export the photos and the library is now back to 1Gb again....backed up hourly/daily/weekly etc what am I left with??
Do I have an original, the 2GB version and the new 1Gb version...ie 4Gb......is there a cunning way I can work to change the files within a week so only one of the changes is in the backup?
You might be able to exclude those files from being backed up at certain times, but I can't be sure this would result in older copied of those files being retained.

How does Time Machine Handle separate Boot and User Volumes?

I recently installed an SSD and set it up as my boot drive, and I'm using another hard drive for my Home folder, if I ever run into a scenario that I need to restore my entire system, how will Time Machine handle it?
Will it restore my system back to the drives that they came off of?, in other words will my Boot volume be restored back to the SSD and my Home folder back to the hard drive, or will it restore everything back on the one disk it asks me to select before I click restore?

Michael Hoover wrote:
Ok, so if I tried to access a backup from booting with the Snow Leopard install disk I won't be able to select which volume I need to restore?
You would restore the OSX volume via the procedure in #14 of [Time Machine - Frequently Asked Questions|http://web.me.com/pondini/Time_Machine/FAQ.html] (or use the link in *User Tips* at the top of this forum).
You would restore the data-only volume separately, via the "Star Wars" display, per #15 in the FAQ.
I guess I would be better off doing incremental backups with Carbon Copy Cloner on 2 partitions on the same volume.
That would also take two separate operations to restore. (It would be a good idea to do such backups +*in addition+* to Time Machine backups, in case there's a problem with either disk drive or backup app, or a user error like erasing the wrong disk.)
Your scenario is actually quite unlikely; you'd rarely need to restore both volumes at once. If the SSD fails, you'd only need to restore it; if the HD fails, you'd only need to restore that.
It would get a bit more complicated if you get a new Mac, especially one with a single volume. That's one of the reasons it's a good idea to keep at least a minimal Admin account on the OSX volume.

How does Time Machine handle multiple profiles?

Hello,
I have an IMac with 3 users, does time machine handle all users?
2 users are admins, but when i change users the time machine does not handle well the external drive.
Can you give some info in this matter.
Thanks
Nuno

It should work fine. All of my machines have multiple users. What problems are you having?

How does Time Machine handle disconnected external media drive ?

I have an external drive connected to my iMac, and backup to a Time Capsule.
I prefer not to keep that external media drive connected all the time...
When I disconnect that external media drive and Time Machine runs, does TM perceive this as "deleted"?
With that drive disconnected, does TM then "release" the prior media drive backup and replace it as it needs space?
When I reconnect the external Media Drive, does TM see it as "new" or recognize it as the prior data and (presuming it's not over-written it) simply manage it incrementally?
Ultimately - do I need to either ensure that the external media drive is always available to use TM, or do I run the risk of screwy / uncertain behavior if it is sometimes present, sometimes not.
Gosh I hope that was clear for you experts out there ;-)
D

an external drive backed up to a TM would forever be retained in the TM... never flushed,
Correct. Except.......if the backup drive is close to becoming full, Time Machine will start to delete the oldest backups to make room for new backups.
So, if you have been backing up the external drive for the last year, and the backup drive is running out of space, you may not be able to go back a full year in Time Machine to see exactly how the external drive looked a year ago. You might only be able to go back 10 months, for example, instead of 12.
Most users really don't ever need to go back more than a few weeks or maybe a month or two to pick up a file that they might have accidentally deleted, so the fact that you might not be able to go back a full year or more to see how the drive looked at that time in the past, is not really that important for most users.
Most of us need to know that we have a complete, up to date backup of the external drive in case it fails.
Time Machine will warn you whenever it starts to delete the oldest backups, so if you really do need to be able to go back a year, or two years, or however long it has been since you originally started to back up the external......and you don't want Time Machine to start deleting the oldest backups of the external to make more room.....then you will need to add another backup drive and start backing up everything to that new drive.

How does time machine handle initial backup after upgrading to Yosemite?

HI All,
I'm wondering if Time machine will create a "new" full backup of the system after I upgrade to Yosemite.
I'm trying to make sure I can backout (revert to previous backup of Mavericks) of the upgrade should I run into trouble.
Thanks,
Eddy817

besides restoring just one file, that is what Time machine DOES. See this article:
Time Machine - Frequently Asked Questions -- 14. How do I restore my entire system?
If you are deeply concerned, you may want make a copy of your entire system before updating (Clone your old system) or Install onto a Blank drive and add your files to that.
If you make NO preparation and do not have a Backup, the only way to install a previous versions is to do so onto a Blank drive. Also, you must have PURCHASED (even for $0) a copy of Mavericks, or it will not be available for re-download.

How does Time Machine handle renamed folders

I am trying to free up some space on my external hard drive that I back up to via Time Machine. I am browsing the backups via the TM "Star Wars" UI deleting some backups I don't need anymore. I notice I have on directory in particular that is around 50 GB, but has been renamed several times, from "Motion Pictures" to "Films" to "My Movies". If I select "delete all backups" of, say, "Motion Pictures, will it delete ALL of these backups even though their name was changed, or only the backups that correspond to the name "Motion Pictures"? (The path of the directory has never changed it has always been in my "movies" folder i.e. ~/Movies/Films or ~/Movies/Motion Pictures". Please only respond if you are 100% sure of this, not an educated guess, as I do not want to lose all of this data.
Thanks for your help!

It should work fine. All of my machines have multiple users. What problems are you having?

How does Time Machine handle renamed folder

I am trying to free up some space on my external hard drive that I back up to via Time Machine. I am browsing the backups via the TM "Star Wars" UI deleting some backups I don't need anymore. I notice I have on directory in particular that is around 50 GB, but has been renamed several times, from "Motion Pictures" to "Films" to "My Movies". If I select "delete all backups" of, say, "Motion Pictures, will it delete ALL of these backups even though their name was changed, or only the backups that correspond to the name "Motion Pictures"? (The path of the directory has never changed it has always been in my "movies" folder i.e. ~/Movies/Films or ~/Movies/Motion Pictures". Please only respond if you are 100% sure of this, not an educated guess, as I do not want to lose all of this data.
Thanks for your help!

It should work fine. All of my machines have multiple users. What problems are you having?

Does Time Machine backup system files (/usr/local/*)?

Does Time Machine backup system files (/usr/local/*)?
If so how do you locate them in the Time Machine interface?
If I go into Time Machine mode and type say "/usr/local" in the Time Machine search bar I get nothing although I can open a terminal application and cd to /usr/local and see bin, lib, include, etc.
Of course I can never see /usr/local in Finder either ... only at the command line.
Thanks.

John, another tech pro ("baltwo") suggests:
Run this in the Terminal:
defaults write com.apple.finder AppleShowAllFiles 1
OPTION-click and hold on Finder's Dock icon->Relaunch which reveals all hidden files. Then, look for that file and delete it. To hide all of those, use the same command, substituiting zero for the one, and relaunch the Finder.

How Does Time Machine Help If... iCal Data Lost?

Hi,
How does Time Machine help if, say, your iCal database gets messed up? Or, how does it help if you accidentally delete all your playlists from iTunes? I'd be interested to know.

That's a very good question (although probably better directed at Apple than us). Because Time Machine is new and Apple's in house programs handle data in different ways, there are a range of different means of recovering data for different applications. Not very user friendly and iCal is one of the least user friendly ones.
As an experiment, because I don't make much use of iCal and have no real idea how it works, I tried to find out how to restore its data. Starting with working with the application: nope, not TM aware at present. OK, where does it restore its data? Next step Spotlight where, as it happens, the obvious search "Calendars" brings up a folder in ~/Library labelled that with a whole lot of mysterious stuff in it. I'm pretty sure that restoring that folder would do the trick. No doubt, if you could figure out which Calendar belongs to what in the above folder you could restore a single calendar that was causing problems. Still, Apple's clearly got some work to do to make this more transparent. Roll on iCal4!
(By the way Mail also restores from within the program).

How does time machine work when being used with a mac pro?

How does time machine work when backing up a mac pro?
Considering the fact that the mac pro can hold 8TB and a external (non NAS) hard drive can hold only 2TB does time machine only backup the OS disk.

macnewcomer22 wrote:
Considering the fact that the mac pro can hold 8TB and a external (non NAS) hard drive can hold only 2TB does time machine only backup the OS disk.
Time Machine will backup everything by default, on every disk in your Mac.
Choose System Preferences > Options to exclude items. You could exclude everything except your OS...but I'd think it is your data that's more important to you, if you have to make choices.
See...
http://discussions.apple.com/thread.jspa?threadID=1964018
While it's true you can store almost 8TB, how much do you think you'll actually store? If you have 1TB of data you want to store then a 2TB drive can do it. Also when your TM drive begins to get full it will begin deleting the oldest backups to make room.
You could also get a Drobo with 8 bays...
http://www.drobo.com/products/index.php
-mj

How does time machine back up separate but computers on the same drive

Thinking about hooking up a hard drive to APBS to use as a time machine for several macs /iPads, how does time machine keep these different devices separate? How does it keep the backup info separate? Thanks

APBS is usually called AEBS or Airport Extreme Base Station.
You can only do Time Machine to the newest one.. it is not supported on earlier models.
See http://pondini.org/TM/Home.html
Look for Gory details about airdisk.
Also it is going to help you to actually read how Time Machine works on network drives.
What you are asking has all the answers there.
http://pondini.org/TM/Works.html
ipads do not backup like macs.. there is no time machine.
ipads backup to itunes or to icloud. The backup to local itunes can then be backed up by TM to the disk you are using.
Please note even though Apple now says it works.. I have seen reports where the old problem has come back.. it works for 6-8weeks and then the backup corrupts itself and you have to start over.

Does Time Machine Ever Delete All Traces of a File?

I have a question. I have read up on Time Machine on various articles, posts, and documents across the web and I am having a hard time understanding exactly how time machine deletes files.
When a disk is full, does Time Machine ever make the decision to delete the last copy or version of a file, therefore completely erasing it off the disk forever? I know that Time Machine deletes older versions of files, but will it ever completely delete the last, final backup of a file to make space? If so, I can't imagine using Time Machine as a true piece of backup software. It seems like it would be useful in restoring your computer in an emergency, but as far as backing up files, it seems that it would be catastrophic, because it may choose to delete the last remaing version of a file to make space and you end up losing that file for ever.
Here is an example:
I create a file X.doc
Time Machine backs it up.
I modify X.doc
Time Machine backs up the copy, keeping both the original and the new copy on the backup drive.
I modify X.doc yet again.
Time Machine drive runs out of space. Time Machine deletes the oldest version of X.doc and backs up the new copy.
I create 10 more files unrelated to X.doc
Will Time Macine remove all remaining versions of X.doc to make space for the 10 new files???
I hope I am making sense.

Derek Doublin1 wrote:
Will Time Macine remove all remaining versions of X.doc to make space for the 10 new files???
The worst TM can do is delete all your older copies of files, not the most recent version.
If the drive is full, then it can't accept any more files period.
If you had a full 100GB boot drive and a 100GB TM drive, the TM drive would be a copy of the boot drive with no room for saved states.
If you changed a file on the full boot drive, then TM updates that file on it's full drive, there will be no copy of the previous version of that file.
TimeMachine makes for a poor pernament backup system, because lets say you do a major files addition to your boot drive, TM backs that up and can go ahead and delete files you realized you accidentially deleted just a few short days ago.
It's better than nothing and works ok for newbies, but more seasoned types use many backup methods in addition to TM, because corruption creep is possible with TM as well as malware as it's hooked up so often, in a lot of cases all the time.
Most commonly used backup methods

How does the EDB handle deleted items and why am I only able to recover some and not all previously deleted emails?

Hello,
I have been unable to locate information regarding how the EDB handles deleted files. I am able to recover deleted emails from the EDB; however, there are numerous emails that I know have been deleted, that were not recovered during the recovery process.
Is this because the EDB dumps deleted emails once it reaches a certain amount of entries? Or is it more likely the deleted items are corrupted and thus not recoverable? Thank you for your time and I look forward to your responses. The
product in question is Microsoft Exchange Server 2007.

Great information from the other posters and one other possible explanation is if the users did a HARD DELETE. More information on this below
Pre-Exchange 2010 Dumpster 1.0 worked as follows;
1. When a user does a normal delete of an item via Outlook or OWA it gets sent to your deleted items folder
2. If the user then empties deleted items folder those items are then marked with the ptagDeletedOnFlag attribute which in essence hides them from the view of the user
3. At this point the user can use the Recover Deleted Items function in Outlook to recover those items as long as the items were NOT purged using the Recover Deleted Items option OR the items have not passed still the deleted item retention period.
NOTE: Every day there is a nightly maintenance process that in short looks through the DB and examines items that have been deleted. Items that have met or exceeded the deleted item retention period are purged from the system and are
completely non-recoverable. More about this at the end of my post.
4. However if the end user were to delete an item from the Inbox or another folder in Outlook by using Shift + Delete aka a Hard Deletion the item is left in its orignal location and gets marked with the ptagDeletedOnFlag attribute which again just
hides it from view.
5. By default you can only use the Recover Deleted Items option on the Delted Items folder. Howeve you can make it so that you can recover hard Deleted items from other folders. More on that here http://support.microsoft.com/kb/246153
5. The problem with this method though IMO is that you have to know where to look and that can be rather time consuming.
6. If you want a more elegant method to resolve this and are open to using 3rd party utilities check out Lucid8's DigiScope.
http://www.lucid8.com/product/digiscope.asp which will allow you to open any offline copy of the DB from a forensic point of view and to solve your specific issue you can either turn on a filter to ONLY
show hard deleted items OR you can search the entire store and all mailboxes for just deleted items and can then view or export them to PST or MSG format. You can download the product and obtain a 30 day demo license which will allow you to find any
hard deleted items, however to view them or export your would need to purchase a license.
NOTE: When a database is backed up or copied it is an "Offline" database and then its offline the data retention period is not an issue because the nightly online maintenance process can only act on a database that is mounted on an
Exchange server. So for this reason if you want to recover the most data possible use offline copies/backups of the DB with a 3rd party utility like DigiScope
NOTE 2: Exchange 2010 and 2013 use Dumpster 2.0 which is an entirely different beast and I will not go into that in this post since its nearly 1AM however DigiScope can expose that information as well
Search, Recover, & Extract Mailboxes, Folders, & Email Items from Offline Exchange Mailbox and Public Folder EDB's and Live Exchange Servers or Import/Migrate direct from Offline EDB to Any Production Exchange Server, even cross version i.e. 2003
--> 2007 --> 2010 --> 2013 with Lucid8's
DigiScope

How does time machine handle deleted files

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