Mike Oscar

Q: Time Machine - I have masses of free space but Time Machine keeps deleting old files - why?

Time Machine - I have masses of free space (about 2.5 TB) but time machine keeps deleting files older than nine months. Is there some limiting parameter I don't know about?  My backup drive is an  early 4 drive Drobo.  I all works fine except this one irritating issue.  Any ideas out there?

iMac with Retina 5K display, OS X El Capitan (10.11.1), Intel Core i7, AMD Radeon R9 graphi

Posted on Nov 30, 2015 8:42 AM

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Q: Time Machine - I have masses of free space but Time Machine keeps deleting old files - why?

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  • by Richard Fernandez,Helpful

    Richard Fernandez Richard Fernandez Nov 30, 2015 9:17 AM in response to Mike Oscar
    Level 1 (34 points)
    Nov 30, 2015 9:17 AM in response to Mike Oscar

    Hello Mike Oscar,

     

              I hope that I am able to assist you today with your concern. If I'm understanding you correctly, in Time Machine, files older than 9 months are being deleted. Time Machine does do this to save space. I'm not too sure if Apple is allowing us to extend this period to lets say 12 months or even 16 months but it would be a great recommendation. I hope that I was able to assist you with your concern.

     

    Best Regards,

    Richard

  • by Mike Oscar,

    Mike Oscar Mike Oscar Nov 30, 2015 9:23 AM in response to Richard Fernandez
    Level 1 (0 points)
    Nov 30, 2015 9:23 AM in response to Richard Fernandez

    Thanks Richard.  I'm aware that Time Machine deletes old files to MAKE space for new backups but I thought it only did this on an as necessary basis, i.e., if there is still plenty of space available there is no need to make some more, if you see what I mean.

  • by William Tomcanin,Helpful

    William Tomcanin William Tomcanin Nov 30, 2015 9:37 AM in response to Mike Oscar
    Level 1 (104 points)
    Mac OS X
    Nov 30, 2015 9:37 AM in response to Mike Oscar

    Yes, that does seem unusual...  my oldest TM backup is 48 months old, and it still hasn't deleted any old backups even with the disk 67% full.

     

    How soon after the installation of El Capitan did you notice this behavior?

  • by Mike Oscar,

    Mike Oscar Mike Oscar Nov 30, 2015 9:44 AM in response to William Tomcanin
    Level 1 (0 points)
    Nov 30, 2015 9:44 AM in response to William Tomcanin

    Hi William, thanks for your post.  It is very encouraging to hear that you have TM backups much older than nine months.  But to be honest I don't think it is El Capitan related, I think my issue goes back beyond that.  Sounds as if it is going to be one of those deep techie things, maybe as much related to Drobo as El Capitan or Time Machine.

  • by Rob Bowers,

    Rob Bowers Rob Bowers Nov 30, 2015 10:32 AM in response to Mike Oscar
    Level 1 (20 points)
    Nov 30, 2015 10:32 AM in response to Mike Oscar

    TM creates a sparse bundle disk image (sort of like an .iso image) which is "thin-provisioned" meaning it can grow, like a VM thin-provisioned disk image.

     

    Most NAS that support TM use some sort of quota so that TM does not consume all of the disk space on the NAS. This is particularly useful when 2+ Macs use the NAS for backups. Similar to how OS X Server can manage quotas for TM backups (Time Capsule does not have a quota mechanism, but Server can manage quotas on a Time Capsule).

     

    Check your Drobo dashboard for Time Machine settings. It appears Drobo creates a separate Volume for TM, so it would stand to reason the entire drive is not available for TM. http://support.drobo.com/app/answers/detail/a_id/608/~/how-do-i-setup-a-backup-a pplication-to-work-with-my-direct-attached-drobo-(das)

  • by Linc Davis,

    Linc Davis Linc Davis Nov 30, 2015 2:34 PM in response to Mike Oscar
    Level 10 (208,000 points)
    Applications
    Nov 30, 2015 2:34 PM in response to Mike Oscar

    "After you set up Time Machine, it automatically makes hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for all previous months."

     

    Use Time Machine to back up or restore your Mac - Apple Support

     

    Since snapshots are being taken every hour, but not all are saved for more than 24 hours, the extra ones must be deleted, regardless of how much space there is. The weekly snapshots are saved until space runs out, then the oldest ones are deleted.

  • by John Lockwood,

    John Lockwood John Lockwood Dec 1, 2015 2:30 AM in response to Rob Bowers
    Level 6 (9,349 points)
    Servers Enterprise
    Dec 1, 2015 2:30 AM in response to Rob Bowers

    Rob Bowers wrote:

     

    TM creates a sparse bundle disk image (sort of like an .iso image) which is "thin-provisioned" meaning it can grow, like a VM thin-provisioned disk image.

     

    Most NAS that support TM use some sort of quota so that TM does not consume all of the disk space on the NAS. This is particularly useful when 2+ Macs use the NAS for backups. Similar to how OS X Server can manage quotas for TM backups (Time Capsule does not have a quota mechanism, but Server can manage quotas on a Time Capsule).

     

     

    Yep this NAS quota for TM is really annoying. I have an old ReadyNAS NV+ I had dedicated to being a TM and it has 6TB of space but NetGear limit the max you can use to 2TB for all TM clients added together. There is a possible workaround I plan to try which is that one can create the invisible file that marks a network volume as being TM compatible on an ordinary share on the NAS, and the ordinary share(s) can have - at least with the ReadyNAS your choice of quota limit including no limit at all. This should then allow using all 6TB of space which since as I mentioned this unit will be dedicated to TM use is fine.

     

    I would not have a problem with the built-in ReadyNAS limit if it let you override it, it does let you decrease it below 2TB which of course does not help me.

  • by Boyd Porter,

    Boyd Porter Boyd Porter Dec 1, 2015 5:49 AM in response to Mike Oscar
    Level 4 (1,017 points)
    Dec 1, 2015 5:49 AM in response to Mike Oscar

    A non-Apple NAS is an unsupported configuration.

     

    Backup disks you can use with Time Machine - Apple Support

     

    Have a nice day.

  • by Mike Oscar,

    Mike Oscar Mike Oscar Dec 2, 2015 2:47 AM in response to William Tomcanin
    Level 1 (0 points)
    Dec 2, 2015 2:47 AM in response to William Tomcanin

    Many thanks to all the correspondents for their helpful responses.  I think the answer lies buried in this 'sparse bundle" stuff (but see also below) and the fact that mine is a 1st Generation Drobo, also perhaps that I am using version 1.8.4 of Drobo Dashboard.  I have learnt the hard way that the later Dashboard versions don't work too well with 1st Gen Drobos so I avoid updating.

     

    I did notice from the referred Drobo Support article that "Using a sparse file bundle to setup Time Machine disables the abitility to "Enter Time Machine." - See more at: http://support.drobo.com/app/answers/detail/a_id/608/~/how-do-i-setup-a-backup-a pplication-to-work-with-my-direct-attached-drobo-(das)#sthash.HZ6yoiWI.dpuf" Now my Drobo DOES allow me to "Enter Time Machine", so I guess it was not set up using that method in which case I guess the answer does not lie "buried in this sparse bundle stuff". In which case I still do not know where the '9 month cut off' parameter is to be found. 

     

    Perhaps it is something to do with my use of a 1st generation Drobo and my learned reluctance to update Dashboard.  Maybe I just have to live with it and just be thankful that I have a good working backup that allows me to retrieve files up to 9 months old.  Thanks everyone.

  • by Rob Bowers,Solvedanswer

    Rob Bowers Rob Bowers Dec 2, 2015 8:51 AM in response to Mike Oscar
    Level 1 (20 points)
    Dec 2, 2015 8:51 AM in response to Mike Oscar

    Mike

     

    I note that in the link you provided, it goes through using OS X Disk Utility to create the backup image, and there is a size parameter. That is where the limit is coming from.

     

    On attached USB, Time Machine will reformat the entire drive to HFS+ when you first set it up as the target disk. To avoid using the entire disk for backups, using Disk Utility, you can create multiple partitions on the USB drive, then select one of the partitions for backups. For connected drives, sparse bundle is not used, rather a Backups.backupdb directory is created and everything is placed under that directory. TM does so because these are generally reserved for the connected Mac only. 

     

    For shared drives like Time Capsule, Time Machine automatically creates a sparse bundle for each Mac using the drive and dynamically resets the size as needed. It likely can do so because of the HFS+ file system on the partition.

     

    But with 3rd party NAS, Time Machine is not natively supported (due to the file system being EXTn or FAT\ExFAT) so you have to trick it by creating an HFS+ file system image and placing it on the target NAS and then using that image (sparse bundle). Basically, the sparse bundle is a disk with it's own file system, residing on another disk with a different file system. Likely, the newer dashboard or Drobo drives use a utility to create the sparse bundle image for you instead of having to go through the Disk Utility steps, thus hiding some of the complexity. It is also possible that older TM (10.5 or so) might have supported shared drives, using a different methodology, and if you have upgraded OS X and continued using the same backup, then maybe it is backwards supported in newer Time Machine versions.

     

    Time Machine will fill up the allocated image space (or USB drive\partition space), and then start removing the oldest incremental files when space is needed for new backups. Likely, the allocated image size you created happens to result in a 9 month cutoff.

     

    Here is a site I ran across a while ago that has some useful, perhaps slightly dated info on TM: http://pondini.org/TM/Home.html

     

    You could remove the current backup on your Drobo, and start fresh (assuming you are satisfied you no longer need the older backups). This time, you could make the size of the image larger. The first backup will obviously take some time, but over time, you will see longer retention as the image size is larger.

     

    All that said, I find it extremely rare to restore files from more than a few days ago. Mostly, my TM backup is used to restore my system if and when I do a fresh install or replace a hard drive in my Mac (I have done this several times over the years as SSD drives come down in price).

  • by Mike Oscar,

    Mike Oscar Mike Oscar Dec 2, 2015 9:47 AM in response to Rob Bowers
    Level 1 (0 points)
    Dec 2, 2015 9:47 AM in response to Rob Bowers

    A truly knowlegeable and helpful reply. Thank you very much Rob, I shall retain all that for future reference.  Thanks again. Mike