04-06-2012, 02:48 AM

I have been using my time machine to back up into an external HD regularly - like every day. I also have been using this to save a lot of my stuff including some documentaries that I watch into the HD. I would copy the video file into my MBP and then back up using time machine. Once it shows up in my backup, I delete the file from my MBP. In this way, I am freeing up space in my MBP but storing all the files so that I can retrieve and watch them later if I want to. However, I sometimes find that some files that I backup like this don't show up in my time machine. I have read that the time machine stores weekly backups and hourly backups. Let's say that I make a backup on Monday. On Tuesday I save a file, back it up and then delete the file. I back up on all the days of the week until next monday. So what exactly does a "weekly" back up mean. After a year/week/month - which backups can I expect to see in my timemachine?

04-06-2012, 03:43 AM

you "see" them all if i understand your question correctly BUT - when the external hard drive is full and it will be sooner or later - the oldest is deleted so you will lose files.
the better option is to put such files on an external HD and leave them there - time machine is the best for a sequential update - e.g. you work on a paper and 2 weeks later you realize that you need the version from 2 weeks ago.

04-06-2012, 04:02 AM

Hai, Thanks for your reply. Let me rephrase my question.

Time machine claims that it backs up files every 24 hours for the last day, every week for the last month and so on. Let say that I backup my Time machine to HD every day for three months - Jan to March. So that I have a weekly back up for January and Feb - and a daily backup for March. Then it's April and I'm guessing - correct me if I am wrong - that TM will now keep weekly backups for March and daily backups for April. My question is - when TM decides to take all the daily updates from March and turn them into weekly updates - how does it choose which files to save and which not do? Does it for example, simply keep all the backups for every Monday in March and throw everything else away? In other words, assuming that I backup my MBP everyday, when should I be deleting files from my MBP so that I can always find it in my TM backup say even a year later? (Let's assume that I have enough space in my HD)

04-06-2012, 04:30 AM

It will always keep the latest version of a file and as many versions of a file until it needs space, at which point it will start deleting the oldest version first.
This daily, weekly monthly thing has nothing to do with physical files ... they are just pointers in the TM database to keep track of which version to keep.
How that technically works internally, no clue .... I just have a lot of confidence in TM and don't worry about that.
On top of TM, I make a monthly bootable clone of my internal hard disk ( Using SuperDuper! ) onto another external drive. Only reason is that if ever something happens to my internal disk, SuperDuper! allows me to be back in business in minutes, whilst I wait for a new hard disk.

Cheers ... McBie

04-06-2012, 05:22 AM

I still don't have a clear reply to my question.
I have a folder on desktop called "My DVD". I copy a video file to it and the back up TM to my HD. After backup I delete the file to free space in my MBP. I back up TM again. Now, how can I ensure that I will find a copy of this file in my TM HD for the longest period of time ? Sometimes, when I go back to my backups from January, I find some files there, but at other times, I cannot find a file that I copied into MY DVD just last week. This has something to do with how TM chooses backups to keep and I am asking if anyone know how time machine selects backups to preserve?

04-06-2012, 05:31 AM

I still don't have a clear reply to my question.
I have a folder on desktop called "My DVD". I copy a video file to it and the back up TM to my HD. After backup I delete the file to free space in my MBP. I back up TM again. Now, how can I ensure that I will find a copy of this file in my TM HD for the longest period of time ? Sometimes, when I go back to my backups from January, I find some files there, but at other times, I cannot find a file that I copied into MY DVD just last week. This has something to do with how TM chooses backups to keep and I am asking if anyone know how time machine selects backups to preserve?

04-06-2012, 06:31 AM

If I understand you correctly, once a file has been backed up to Time Machine you are deleting it from your hard drive. THIS IS A REALLY STUPID THING TO DO.

Time machine is a BACK UP. If you delete a file from your hard drive you no longer have a back up so what do you do when Time Machine crashes. That is a hard drive as well so it is just as likely to crash as you computer's drive.

Never delete a file from your hard drive that you think you may need in the future. I understand your question about what files are on Time Machine after a long period but that should hardly ever be a question as the software is not intended to be used that way. It does not have an infinite capacity so it clearly has to delete files at some stage. You should never need to worry about which files it deletes as they will be very old and if you still need them they will be on your main hard drive anyway and will appear on the most recent back up.

On the rare occasions that I need to get a file from Time Machine it is because I have deleted from the main hard drive in error. Then I only need to go back to the last backup. On odd occasions I have had to go further if I find I need to refer to an old email that I deleted as I didn't think I would ever need it again.

As with many users I don't rely on Time Machine alone for important files anyway. It is a quick fix but for my photo archive that goes back to my Grandparent's pictures scanned in it auto backups to Time Machine, I keep a copy of all pictures on another drive and copy all pictures from my iMac to my MacBook Pro. Hard drive space is really cheap so why rely on only one or two copies of anything.

04-06-2012, 06:55 AM

For things I want to backup permanently, I create a separate folder on my Time Machine drive and keep them on there. At any given point I have two of everything I need. I've never had a hard drive crash on my, but if I did, I'd go out and replace it immediately so I'd still have two of everything.

04-06-2012, 11:34 AM

For things I want to backup permanently, I create a separate folder on my Time Machine drive and keep them on there. At any given point I have two of everything I need. I've never had a hard drive crash on my, but if I did, I'd go out and replace it immediately so I'd still have two of everything.

I don't see the point of keeping a second copy on a Time Machine drive. If/when the drive crashes you lose both Time Machine AND the second copy.

As noted on my last post, hard drives are cheap today so keep copies on different drives, not different folders or partitions.

04-06-2012, 01:41 PM

Vinven7: If you can afford a second external, then you should probably get one, tho, I agree with Oneironaut. While TM is a backup solution, it isn't faultless, especially given how often it needs to access and write to disk... From the sounds of what you are doing/wanting to do, it would be better that you either have a seperate folder for things you want to backup but deleted from your MBP. From my understanding, TM does backup your machine as is, and as TheMacMania said, eventually it will delete the oldest. Also from my understanding from Apple's website, "TM keeps track of files and folders that have changed since your last backup so that it only backs up those files and folders. If Time Machine loses track of files and folders that have changed since the last backup, it will compare an "inventory" of your current data to an inventory of your backup." I'm not sure what this would mean to weekly/Monthly etc, my guess is it compares your HD to a weekly/monthly list. So then it would only be backing up what you haven't deleted, and from the Wikipedia, it sounds as if it consolidates them for a week/month (?) which my guess wouldn't include what may have been deleted during that week.

I think you should do what Oneironaut suggested. You could use finder or spotlight to search for older deleted files in TM (I found that finder doesn't always find things so when it fails and I know it's there I use (free) EasyFind and/or ifilex, I've found that EasyFind finds everything on externals all at once and then put them in an external seperate folder.

Just found this from Wikipedia "Time Machine saves hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for everything older than a month until the volume runs out of space. At that point, Time Machine deletes the oldest weekly backup" Time Machine (Mac OS) - Wikipedia, the free encyclopedia

Hope that helps..

04-06-2012, 01:53 PM

Maybe I am going round in circles here but TIME MACHINE IS NOT AN ARCHIVE. It is a safety belt. If you want to archive files buy a second hard drive. If you want to be able to restore your system to how it was yesterday Time Machine is great. If you want to get back a file you deleted in error it is also great. If you want to keep a file archive buy another drive. Don't put files on the Time Machine drive.

My first hard drive cost me £250 for 1.6 Gbyte. Today I can buy a 2 Terrabyte drive for less than £100 so why is anyone even thinking about using the backup drive as a archive.

04-06-2012, 02:01 PM

+1. Have to agree with member AndyClift. He's right on target about backups and archiving.

04-08-2012, 03:21 AM

Some good points here thank you.

This thread raises some very important questions that have bothered me since I had a system problem whilst doing a first time TM back up on a new external HD. I was advised that the TM back up was probably corrupt.

How do we know that a regular TM back up is not corrupt? Can we test the integrity of the back up ? Should we be running Disk Utility regularly on the external HD ? (That in itself may be a facile question but how many of us do it?)

04-08-2012, 04:19 AM

Pendlewitch

More info. needed. What system problem did you have when you did the first backup and how did you know the resulting backup was corrupt.

As far as I am concerned backing up to time Machine is the same as saving a file. You do it and the system saves the file/backup and you forget it. In three years of Macs (iMac, Macbook, MacBook Pro, MacBook Air) plus more years of using PCs than I care to remember (I go back to Sinclair ZX81s and BBC Micro and Amigas) there has only been two situations where I have had a corrupt file and that was when power was lost during saving or a hard drive failed (once). My use for my computer has been for running a business producing promo video. This could mean many weeks of work reliant on video files on a hard drive. In the days of V expensive drives and slow read/write rates I could never have a back up of these files and never had a failure.

On all my Macs I have on occasion had the need to restore the system using the last Time Machine backup and have also had to find files on Time Machine that I had deleted from my Mac and have never had a problem so I think you are getting too concerned.

I let my iMac backup automatically, my MacBooks don't get plugged into their Time Machine hard drives very often so back up every week or so. Important files are also saved to a separate backup drive and/or a DVD ROM. That gives me two backups of everything that matters. If they all fail I think I would go back to pencil and paper.

Last silly question. Do you ever fly? Aircraft systems normally have two backups to allow for failure. if they all fails YOU DIE. A suggest if you are concerned about three hard drives all failing at the same time, don't travel by air !!

04-08-2012, 05:16 AM

My questions are perfectly reasonable in the scheme of things and are more borne out of curiosity than of any major concern.
If all this went down on me tomorrow then c'est la vie, obviously not so for you.

It was a kernel panic shortly after the last Lion update which for a lot of people was troublesome. It coincided with me hooking up a new drive to replace one that was too small for TM.The TM back up had continued on re-boot from where it left off.
I was advised by an Apple Care repair specialist (whom I just happened to come across in my line of work a couple of days later) that the TM back up was most likely corrupt and that I should wipe the drive and perform a new one which I did. Who better to ask I wonder?

Sinclairs, Amiga's, and patronising me about aircraft isn't really answering anything.