Time Machine Questions

Posted:
in macOS edited January 2014
About how big of a hard drive should i buy for this. i will want quite a while saved, maybe a month or two behind. i mean i was thinking of either a 250 of 500 gig, maybe even 1 tb, it depends. i want to have about 100 gig left for movie storage and stuff i dont use often, it all depends on how many gigs time machine will take up. are there any apps like time machine out there right now.
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Comments

  • Reply 1 of 27
    dave k.dave k. Posts: 1,306member
    I have this very same question. Exactly what the hell Time Machine backs up is still somewhat a mystery. Does it only back up stuff in my documents? Or does it back up the entire hard drive?
  • Reply 2 of 27
    well, i know that what it does it it makes like a copy of sorts of your computer on a certain day.lets say you delete a doc on tuesay it has the ability to go back to that day and get that file. lets say you change a file, it can go back to a day when it was the way you wanted, or it can just back individual things. but i dunno how much room it will take.
  • Reply 3 of 27
    Quote:
    Originally Posted by Dave K. View Post


    I have this very same question. Exactly what the hell Time Machine backs up is still somewhat a mystery. Does it only back up stuff in my documents? Or does it back up the entire hard drive?



    It's not a mystery. It has clearly been stated by Apple that it backs up everything - every document, every song, every movie, every photo in your iPhoto. It even backs up MacOS X. The idea is that if your hard drive was to die, you can replace it and restore to your last backup immediately.



    However, in the System Prefs there is a bit where you can list all of the files/folders you don't want backed up.
  • Reply 4 of 27
    project2501project2501 Posts: 433member
    Quote:
    Originally Posted by agent_orange View Post


    It's not a mystery. It has clearly been stated by Apple that it backs up everything - every document, every song, every movie, every photo in your iPhoto. It even backs up MacOS X. The idea is that if your hard drive was to die, you can replace it and restore to your last backup immediately.



    However, in the System Prefs there is a bit where you can list all of the files/folders you don't want backed up.



    It probably backs up all your personal files, but leaves apps and osx files behind, no need to copy those, Id'quess. It probably firstly does complete back up, and after that stores incremental changes to that data. So the storage capacity you need is dependent to how big your work disk is, and how frequently your data is changed.
  • Reply 5 of 27
    dutch peardutch pear Posts: 588member
    Quote:
    Originally Posted by Project2501 View Post


    It probably backs up all your personal files, but leaves apps and osx files behind, no need to copy those, Id'quess. It probably firstly does complete back up, and after that stores incremental changes to that data. So the storage capacity you need is dependent to how big your work disk is, and how frequently your data is changed.



    I'm also hoping it does a good job of compressing the data as much as possible.
  • Reply 6 of 27
    l33r0yl33r0y Posts: 94member
    ...or indeed what kind of files you are changing...



    Example, if your changing high definition video files and you want a 2 month history of such data, your going to need a heck of a lot of storage.



    If you are working with text documents mostly, you'll need a lot less storage.



    I wouldn't waste much time in trying to calculate how much is the optimum storage you'll need - just invest in as much as you can afford.



    A 1Gb SATA3 drive can be had for around $200 nowdays. Think of it in these terms: if you lost a quarter of your valuable data, would you pay a measly 200 bucks to get it back? If the data is valuable, then spend the money and get a big drive - you can always partition it 50:50 for extra data:time machine storage....
  • Reply 7 of 27
    MarvinMarvin Posts: 14,223moderator
    Time Machine creates a hierarchy of folders listed by date with the same layout as your current drive. So if your drive is:



    /apps

    /docs

    /system

    /users



    then Time Machine recreates this layout in every snapshot in a dated folder (this is why I suspect it may not be bootable). Naturally it will store the changes since the last backup. I'm not sure about compression, it looked like they were just stored normally, possibly for speed.



    Then again, it would make sense for them to do this to save totally screwing up the LaunchServices database unless they've fixed this in Leopard.



    You get an option to not backup system stuff and whatever folders you choose. No matter if you miss out certain folders, it still creates the directories (not sure if it's all the way down though), it just doesn't put anything in them.
  • Reply 8 of 27
    i suppose my data wont be that valuble. i mean i am planning to maybe start with some video editing and i will have some typed essays and such, nothing big.
  • Reply 9 of 27
    project2501project2501 Posts: 433member
    Quote:
    Originally Posted by l33r0y View Post


    ...or indeed what kind of files you are changing...



    Example, if your changing high definition video files and you want a 2 month history of such data, your going to need a heck of a lot of storage.



    If you are working with text documents mostly, you'll need a lot less storage.



    I wouldn't waste much time in trying to calculate how much is the optimum storage you'll need - just invest in as much as you can afford.



    A 1Gb SATA3 drive can be had for around $200 nowdays. Think of it in these terms: if you lost a quarter of your valuable data, would you pay a measly 200 bucks to get it back? If the data is valuable, then spend the money and get a big drive - you can always partition it 50:50 for extra data:time machine storage....



    Movie editing produces ridiculous amounts of data, luckily cache files don't need to be backed up, but still even only the video file gets protection it still easily changes quite a lot between versions, and will take lot of storage space.



    Quote:
    Originally Posted by polarissucks View Post


    i suppose my data wont be that valuable. i mean i am planning to maybe start with some video editing and i will have some typed essays and such, nothing big.



    Every one needs to evaluate their back up need, but if you ever lost anything valuable, you surely would want to have back up. Backup drive doesn't really have to be so big, only the most valuable things. Personal texts and photos, don't take too much space. Home videos need much more space, but they are probably better stored on DVD and DV tapes anyways. Time machine doesn't really bring anything new, it just makes it easy to do, and more reachable to anyone
  • Reply 10 of 27
    kcmackcmac Posts: 1,051member
    I could be completely wrong, but this is why I thought the ZFS thing is so big. You just connect externals and it automagically makes it look like one hard drive. You can simply just keep adding on, no muss, no fuss. Is this correct? So if you can only get a little bit at a time, it is no big deal.



    Also would be very helpful for the burgeoning photo, music and video files we are all accumulating.
  • Reply 11 of 27
    l33r0yl33r0y Posts: 94member
    Quote:
    Originally Posted by kcmac View Post


    I could be completely wrong, but this is why I thought the ZFS thing is so big. You just connect externals and it automagically makes it look like one hard drive. You can simply just keep adding on, no muss, no fuss. Is this correct? So if you can only get a little bit at a time, it is no big deal.



    Also would be very helpful for the burgeoning photo, music and video files we are all accumulating.



    I don't think that scenario will help in terms of backing up files, it will only help with expanding your storage.
  • Reply 12 of 27
    I repeat: it CLEARLY states on Apple's website that it BACKS UP EVERYTHING unless otherwise instructed. The Time Machine page on Apple's website reads:



    "Back up everything.

    Time Machine keeps an up-to-date copy of everything on your Mac. That includes system files, applications, accounts, preferences, music, photos, movies, and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of every file, it remembers how your system looked on any given day — so you can revisit your Mac as it appeared in the past."



    Furthermore. When Leopard was first previewed in San Francisco in January, the man who demonstrated it clearly stated it backups up all files - every system file, every document, every song, every preference file, every email, every thumbnail etc etc
  • Reply 13 of 27
    dave k.dave k. Posts: 1,306member
    Quote:
    Originally Posted by agent_orange View Post


    I repeat: it CLEARLY states on Apple's website that it BACKS UP EVERYTHING unless otherwise instructed. The Time Machine page on Apple's website reads:



    "Back up everything.

    Time Machine keeps an up-to-date copy of everything on your Mac. That includes system files, applications, accounts, preferences, music, photos, movies, and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of every file, it remembers how your system looked on any given day ? so you can revisit your Mac as it appeared in the past."



    Furthermore. When Leopard was first previewed in San Francisco in January, the man who demonstrated it clearly stated it backups up all files - every system file, every document, every song, every preference file, every email, every thumbnail etc etc



    Just how large of an external hard drive is needed then? Double your internal hard drive size? What about external hard drives that I am currently using? Does TM work with them too?



    So when I install a 100+ MB system update it keeps both versions until sometime in the future when the old one is overwritten? Same for every app that gets updated? What about demo apps or quicktime movies that I instal/download and then delete? Does it keep those too? What's the point of backing up temp files like internet cache? It seems like TM wastes a huge amount of space.



    Too bad Jobs didn't demo uninstalling a system update or an application update from Time Machine. Something tells me that TM breaks down when trying to do just that.



    Dave
  • Reply 14 of 27
    royboyroyboy Posts: 447member
    Quote:
    Originally Posted by Dave K. View Post


    Just how large of an external hard drive is needed then? Double your internal hard drive size? What about external hard drives that I am currently using? Does TM work with them too?



    So when I install a 100+ MB system update it keeps both versions until sometime in the future when the old one is overwritten? Same for every app that gets updated? What about demo apps or quicktime movies that I instal/download and then delete? Does it keep those too? What's the point of backing up temp files like internet cache? It seems like TM wastes a huge amount of space.



    Too bad Jobs didn't demo uninstalling a system update or an application update from Time Machine. Something tells me that TM breaks down when trying to do just that.



    Dave



    Perhaps TM saves in this manner:



    7/9/07 File: Computer Sales 10MB

    7/10/07 Changes to Computer Sales 12K

    7/11/07 Changes to Computer Sales 19K

    7/12/07 Changes to Computer Sales 14K



    Thus you would have one master file and all the smaller "Change " files. You would have 10MB plus changes equaling to 45K for a total of 10MB plus 45K. Not the 40MB TM saved if there was a 10MB file and it was changed 3 times. That's my idea and I'm sticking with it until Steve tells us how TM works.
  • Reply 15 of 27
    MarvinMarvin Posts: 14,223moderator
    Quote:
    Originally Posted by Dave K. View Post


    Just how large of an external hard drive is needed then? Double your internal hard drive size? What about external hard drives that I am currently using? Does TM work with them too?



    I think Time Machine only backs up the current boot volume so I doubt it would back up an external drive to another if that's what you mean. If you mean will it back up to your current drives then yes.



    As for size, it depends on what you do and how often you backup as well as how big your drive is and how much of it you use. If it's on automatic, which I wouldn't recommend, it will likely use more space than necessary. Also, you should really set it to delete changes that are more than a month old if even that much.



    Quote:
    Originally Posted by Dave K. View Post


    What's the point of backing up temp files like internet cache? It seems like TM wastes a huge amount of space.



    It maybe doesn't back those up. It only asks you if you want to back up the system, it doesn't give specifics about whether or not it backs up everything.



    Quote:
    Originally Posted by Dave K. View Post


    Too bad Jobs didn't demo uninstalling a system update or an application update from Time Machine. Something tells me that TM breaks down when trying to do just that.



    You wouldn't be able to do that with a booted system anyway. You'd have to boot from the system disc and restore the system folder to an earlier version. I don't think that would break.
  • Reply 16 of 27
    debenmdebenm Posts: 99member
    Perhaps time machine handles files like aperture does images... when you make a change the image isn't changed ~ it stays the same, but a small txt file of sorts contains all the image corrections and changes.



    So, maybe TM takes a file that you created, saved that main file to the ext HD and then each time you change that file it writes a little meta file for the date and time you changed it with the appropriate changes referencing to the original file... just a thought.
  • Reply 17 of 27
    MarvinMarvin Posts: 14,223moderator
    Quote:
    Originally Posted by debenm View Post


    Perhaps time machine handles files like aperture does images... when you make a change the image isn't changed ~ it stays the same, but a small txt file of sorts contains all the image corrections and changes.



    So, maybe TM takes a file that you created, saved that main file to the ext HD and then each time you change that file it writes a little meta file for the date and time you changed it with the appropriate changes referencing to the original file... just a thought.



    No that's not possible with the majority of files because they are stored as a binary. It would have to store the binary segment that has changed and then on recovery inject that back into the binary itself at the correct place. This wouldn't be very practical and is quite unsafe.



    Aperture doesn't work by remembering changes made to a file but rather the workflow used in order to make the changes.
  • Reply 18 of 27
    Quote:
    Originally Posted by Marvin View Post


    No that's not possible with the majority of files because they are stored as a binary. It would have to store the binary segment that has changed and then on recovery inject that back into the binary itself at the correct place. This wouldn't be very practical and is quite unsafe.



    Aperture doesn't work by remembering changes made to a file but rather the workflow used in order to make the changes.



    Data is already saved to your hard drive in sectors, they are the smallest physically saved addressable data units, so all TM has to do is copy the changed sectors.
  • Reply 19 of 27
    zoczoc Posts: 77member
    Quote:
    Originally Posted by Project2501 View Post


    Data is already saved to your hard drive in sectors, they are the smallest physically saved addressable data units, so all TM has to do is copy the changed sectors.



    Yes, but TM does not work at the sector level, but only at the file level.



    Conclusion : You have a 1 Gb file somewhere, you modify only 1 byte. The size of the TM backup for this file will be 1 Gb.



    TM is only some sort of rsync/rsnapshot (commonly used to backup unix systems), with a nice GUI around it.
  • Reply 20 of 27
    I wonder how Time Machine will handle secure delete. If there's a file I'm using and I need to delete that file and it's contents using the secure delete feature called "Secure Empty Trash", will Time Machine search through all of the backups and secure delete all of them? If so, would that be a long process?
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