Does Time Machine Copy UNCHANGED files over and over??

Okay, it seems to me that whatever files I have selected for backup are copied by Time Machine EVERY SINGLE TIME it backs up my Mac, instead of just when I make changes to them. Is that correct? If so, that just seems to be a massive waste of space on the external hard drive, and is probably the reason my 1TB drive runs out of space so quickly.
For example, I don't need 50 copies of my iTunes Library. I just need ONE copy. Time Machine should back up the music files ONCE, and if I add more songs to iTunes, it should then detect it and backup JUST the new files. Same thing with a Word document or whatever...make ONE copy of the file and then if I ALTER the file, make a copy of the ALTERED FILE.
Am I making sense here or is this just wishful thinking? Is there a way to make these types of adjustments in settings that I am missing?
Thanks!

Shugama wrote:
Okay, it seems to me that whatever files I have selected for backup are copied by Time Machine EVERY SINGLE TIME it backs up my Mac, instead of just when I make changes to them. Is that correct?
no, that's wrong. that would indeed be a huge waste of space. TM only backs up afresh new and changed files since the last backup. everything else is *hard linked* to existing backup copies. read up on what a hard link is.
http://en.wikipedia.org/wiki/Hard_link
that's why incremental backups take very little space and yet every single TM backup is a full and completely independent copy of your system at the backup time. and that's why you can have a lot of TM backups fit on your backup drive.
If so, that just seems to be a massive waste of space on the external hard drive, and is probably the reason my 1TB drive runs out of space so quickly.
For example, I don't need 50 copies of my iTunes Library. I just need ONE copy. Time Machine should back up the music files ONCE, and if I add more songs to iTunes, it should then detect it and backup JUST the new files. Same thing with a Word document or whatever...make ONE copy of the file and then if I ALTER the file, make a copy of the ALTERED FILE.
Am I making sense here or is this just wishful thinking? Is there a way to make these types of adjustments in settings that I am missing?
Thanks!

Similar Messages

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.

Does Time Machine Compare/Verify Files?

I have typically performed manual backups, and have no experience with Time Machine.
Does Time Machine COMPARE / VERIFY that the backup files match the originals?
I used to use Retrospect for Archive/Backup, which logged an alert if there was any mis-match in the backup process. Now I tend to backup files simply using Drag/Drop copying to redundant external storage devices. I have recently encountered errors in this process when backing up larger amounts of data. Hopefully this will not occur using TIme Machine.
What does Time Machine do if there is an error in the backup process?
Is Time Machine the most reliable solution for Archive/Backup?
thanks

Time Machine logs to the system.log as process com.apple.backupd, which you can access via Appplications -> Utilities -> Console
Carbon Copy Cloner logs to a CCC.log which you can access from within CCC, or via Applications -> Utilities -> Console.
CCC will popup and error if there is backup problem.
SuperDuper has its own built-in log, that you access via SuperDuper.
SuperDuper will popup an error if there is a backup problem.
CrashPlan has a /Library/Logs/CrashPlan/ directory with backup logs.
CrashPlan can send you an email if there is a backup problem. Even better, it will tell you if a backup has not completed within the last 3 days. I find that very nice in that automatic backups that stop and you haven't noticed it, is more annoying than not having a backup verification.
I also remember Retrospect. And the verify taking longer than the backup is a good excuse to just make another backup using a different utility and media destination.

Time Machine deletes "unchanged" files at some point?

I am worried with the fate of old files backed up with Time Machine and that are not changed, like old pictures.
I was told that after the first backup, Time Machine works by making links to unchanged files to avoid copying everything not changed.
_My question_: when Time Machine automatically deletes old backups to make save for the new backups - is it possible that these unchanged files (such a specific old pictures file) be also deleted ? In other words, some of _my old pictures might vanish of Time Machine if its file is not changed_?

Mikus wrote:
I am worried with the fate of old files backed up with Time Machine and that are not changed, like old pictures.
I was told that after the first backup, Time Machine works by making links to unchanged files to avoid copying everything not changed.
Correct.
_My question_: when Time Machine automatically deletes old backups to make save for the new backups - is it possible that these unchanged files (such a specific old pictures file) be also deleted ? In other words, some of _my old pictures might vanish of Time Machine if its file is not changed_?
No. As Malcolm says, Time Machine always has copies of everything currently on your Mac. Every Time Machine backup is, in effect, a full one -- a complete "snapshot" of your entire system.
See How Time Machine works its Magic for an explanation.

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

Does Time Machine replace changed files and delete old files?

I haven't upgraded to Leopard yet, but my son is a NEW CONVERT to the Mac; has uses Dells for years. He has a new Macbook Pro with Leopard. I use SuperDuper! with my Tiger Mini Mac.
I don't understand what Time Machine does. Does it continually update files on the target device, and if so how does it handle deleted and renamed files on the source device.
Thanks.

Time Machine takes a snapshot of the drive it is backing up every hour. If a file is new, renamed or modified since its last backup, Time Machine will make a physical copy of that file. To conserve drive space Time Machine will only make hard links back to its previously backed up files for files that exist on its source drive which remain unchanged. Hard links work in a somewhat similar fashion as aliases. If a file has been deleted Time Machine won't make a copy or hard link. You can read about how hard links work in Time Machine in this Ars Technica review.
http://arstechnica.com/reviews/os/mac-os-x-10-5.ars/14
If a file is not on the hard drive for over an hour and is deleted before Time Machine makes its hourly backup that file will not be in any of Time Machine's backups.
Time Machine only retains the first hourly backup of the day as its daily backup. The other hourly backups get deleted in the course of the day. That means that to be retained in the daily backups a file must be on the hard drive for over a day or be physically present on the source drive for the first backup of the day.
After a month, Time Machine retains the daily backup made on the same day of the week as the initial backup as its weekly backup. If a file is on the source drive for less than a week and is not in the daily backup retained as the weekly it will end up being deleted when Time Machine thins its daily backups.
When the Time Machine volume fills up, Time Machine will start deleting its earliest backups to make room for new ones.

Does time machine identify any file replications?

Hi all,
I am wondering whether anyone knows more about this, looked into this.
- I know that time machine does use links to ensure that files that belong to multiple snapshots (successive snapshots)
are not backed more than once.
However, recently I had to reset my Mac (MacBook Pro) from 10.7.5 to 10.7.4, because there were problems in operation.
(actually with time machine and Spotlight, but I do not think, this is the issue here).
I simply reinstalled the version from about two weeks earlier - in the meantime there were not a large number of changes.
However, the next time the backup was about 80 GB.
This made me wonder under which conditions does TM actually identify a file that it has already backuped before
and it does only need to link it and not back up it up again:
only if it is at the very same position and it has no modified change date (of course also no content change)?
- this would mean the complete system actully would have been backuped again - not nice, but would roughly fit the size.
or are there more conditions?
It also seems that any files that are moved lead to a replicate backup. - the file at the new position is treated as a new backup.
Also if temporarily some location was excluded from the backup and then the exclusion is removed, it seems the next backup contains
an all-fresh replica.
In these and many other cases, a lot of space could be gained, if multiple occurances of files would be treated as a single file with
a hard-link in the backup.
a) It seems this is in no way addressed by TM
b) It seems that this might be compatible with the way TM manages backups. (files can be hardlinks)
Thus, does an utility exist, which is able to identify such copies in a backup and replace the identical copies by a single
copy with hard links? Does someone know more about the inner management of TM-backups? Could this approach work?
I know that this is not directly supported by TM, but I am just curious whether something like this exists, it seems to me
that due to my restoration and the way I handle data (e.g., put everything for working on the desktop - later move it to the
final destination), there would be very many opportunities to thus compress the size of TM-backups.
Cheers
Klaus

It says it will notify you after a backup is deleted. That's the only option available. You will have to open the TM backup and see where the file dates you wish to keep are and manually track them if you need TM to store files you deleted from your current system.
If you delete a file from your current system that you need to keep long term, then I wouldn't rely on a TM backup to store it. You should either keep it on the computer and you will always have a TM backup. If you need to clear space on the computer, you should back up important files to another location such as a flash drive or external drive.

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 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.

Backing up with Time Machine via "Personal File Sharing" and Airport Disk

I've been using Time Machine on my own Mac at home and want to use it to backup other Macs in my house as well. Right now I'm just backing up over FireWire, but plugging my disk into each of the other Macs one at a time doesn't seem to make much sense.
Besides going out and buying a Time Capsule, Leopard Server, or Xsan, what are my options for backing up multiple Macs to one disk? I've read that using an Airport disk is somewhat risky because of some "premature file transfer confirmation." Has anyone ever used Time Machine w/ Airport Disk and had problems?
I've also noticed that you can back up to shared drives, like if I share my current FireWire disk so people can back up to it, but wouldn't that require for people to connect to the host Mac manually via Finder? And wouldn't that in turn defeat the purpose of automatic scheduled backups?
Any advice or suggestions would be appreciated.

the only supported option besides Time Capsule is to back up to a hard drive directly connected to a mac running leopard on the same local network. as you mention it would indeed require that this drive be mounted first. you can automate mounting this drive on login and simply keep it mounted at all times. to do that mount the drive of the host Mac on a remote mac and while it's mounted there add it to the login items in system preferences->accounts.
You can also use drives directly attached to an airport extreme base station. that works in the same way as backups to a Time capsule.
Message was edited by: V.K.

Does time machine backup open files that I am currently working on?

Will time machine backup files that are open? I have a quickbooks file or others that sometimes will be open for as long as a week. I was having problems with a file I was working on that had days worth of data that I had been changed. When I tried to restore a file with time machine, I had to go back a week. All my changes were lost. I assumed that time machine would be backing up a file even as I was working on it. Maybe not? Can find very little info anywhere. Yosemite 10.10.1

I don't believe it does. I know that there was an issue in the past where it wouldn't back up any of the iPhoto Library if iPhoto was open. I don't know if that was fixed. But, like you, I can't find anything else to verify my suspicion.
If the program supports Auto-save and Versions, then you would be able to go back through the versions, but I don't think QuickBooks would support that.

Time Machine Copying all files again after a restore

i recently achieved a successful restore of my computer and now i am wishing to back up my computer again (after installing bootcamp) but time machine keeps trying to backup all my files
my computers name is still the same and when i force a backup the inprocess icon comes up in my external drive(where it should be) but then says there isnt enough space. it also seems to want to back more information then i have on my original hard drive?it also deleted my earlier backups without consent
any help would be greatly appreciated

I would imagine that reformatting the hard drive would remove the event logs that Time Machine uses to determine what has changed since the last backup and so it would be likely to fully backup from scratch. You should be able to view previous backups using the Browse Other Time Machine Volumes menu item in Time Machine given that your computer name is unchanged.

Time Machine - Copying old Files to new Hard Drive

Need Assistance to be able to copy time machine files from one external drive to another, to allow continuation of time machine without erasing older copies, spoke to apple support, they informed me that there is a third party software (untility) that will enable you to do that, has any bod have info on this issue, Thank You

Mtaff wrote:
Need Assistance to be able to copy time machine files from one external drive to another, to allow continuation of time machine without erasing older copies, spoke to apple support, they informed me that there is a third party software (untility) that will enable you to do that
Are your files on a local disk or a Time Capsule? I was able to use a Finder drag-and-drop to copy "sparsebundle" files from one Time Capsule to another, although I had to copy them to an intermediate device and then to the final destination.
If your Time Machine files are on a directly-attached disk, you might be able to copy then with the utility SuperDuper! (exclamation point part of the name):
http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html

Does Time Machine backup open applications/files?

I recently lost my calendars (in Entourage, Ical, Mobileme, etc.), and wanted to restore from a time machine backup.
I tried to restore the Entourage identity from a day or two before only to see that the date in Time Machine for the file was way old.
I suspected that because I leave the app open all the time, particularly all night when my backups run at 11 pm that the file never got backed up. Does this sound right?
Ical, on the other hand (which is synched to mobile me and entourage), even though I rarely open it and use it, seemed to have the updated data.
How does Time Machine deal with files that are in use?

Entourage needs some special handling. I don't use it, so can't tell you exactly how to do it, but if you search this forum for Entourage you should find a post or two (by Kappy and/or Baltwo, I think) with good advice.

Time machine - timing question (how often) and applications question

1. A hypothetical: if I boot up the iMac and make changes to a file and shutdown, all within a 15 minute time frame - - then, for whatever reason repeat that later the same day because I need to change the file once again (and again, just another 15 minute session) - - - has Time Machine captured both or either of those changed files?
What if these two changes were both made within the same hour? Which backup if any would it capture?
I'm letting the hourly backup timing confuse me. Does Time Machine capture changed files at startup, as long as at least 1 hour has passed since last backup?
2. Applications - is my assumption correct that you don't want to restore Apps from Time Machine since you're not likely to restore plist or other related files that reside elsewhere on the hard drive?
Thanks in advance

DHodges wrote:
1. A hypothetical: if I boot up the iMac and make changes to a file and shutdown, all within a 15 minute time frame - - then, for whatever reason repeat that later the same day because I need to change the file once again (and again, just another 15 minute session) - - - has Time Machine captured both or either of those changed files?
Probably. When your Mac starts, it will run a backup immediately unless a backup was done within the previous hour. So assuming the last thing you do before powering-down is to save the file; if "later that same day" is under 45 minutes, the first one might not be saved; if it's over 45, depending on exactly when you save the second version, either the first or second would be saved on that backup.
I realize this is theoretical, but Apple recommends sleeping your Mac instead of powering-down unless your iMac won't be used for "several days." See: [Sleeping your Mac vs. Powering it Down|http://web.me.com/pondini/AppleTips/Sleep.html].
I'm letting the hourly backup timing confuse me. Does Time Machine capture changed files at startup, as long as at least 1 hour has passed since last backup?
Yes.
2. Applications - is my assumption correct that you don't want to restore Apps from Time Machine since you're not likely to restore plist or other related files that reside elsewhere on the hard drive?
As Thomas says, that's usually not a good idea for complex apps (generally, the ones that come with their own Installers), but is fine for those installed by drag & drop.
And yes, even for those, you'd have to restore the preferences file or re-enter the settings, and of course the data, too, wherever that is.

Does Time Machine Copy UNCHANGED files over and over??

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