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  1. #1
    Backing up Time Machine using another Time Machine
    Hi there, I wonder if anyone can help me. Sorry if I don't explain this very well...

    I have a portable TM drive that I use to back up my main Mac. What I'd like to be able to do is plug this portable TM drive into my laptop at home and have its TM (a larger desktop drive) back up my laptop as well as the portable TM drive (as if it was just another external drive attached to my laptop). When I try this, although I have removed the portable TM drive from the exclude list, it won't back it up. I assume it's because my laptop sees the portable TM as a TM backup (even though it's not for the Mac its attached too) and excludes it anyway. Does anyone know if there is a way around this so I can have my home laptop back itself up as well as the attached TM drive?

    I'm preparing myself for a 'this cannot be done, you need to think of another solution' type reply but I thought I'd ask in case there was something that could be done in Terminal etc.

    Thanks for reading all of that (if you did) and thanks for any help you can give
    J

  2. #2
    Backing up Time Machine using another Time Machine
    IWT's Avatar
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    Firstly, a very warm welcome to our Forums.

    I may not be reading your request properly, but if you have more than one Mac but don’t want to use a separate hard drive to back up each one, Time Machine can do this.

    Here are two articles discussing this:

    https://www.macworld.com/article/113...plebackup.html
    https://forums.macrumors.com/threads...ernal.2022172/

    I may, of course, be misunderstanding your intentions.

    What I would say, however, is that the cost of a spinning platter External Hard Drive (EHD) is negligible in comparison to that of a Mac, let alone two Macs.

    It would be much better if you had an EHD dedicated to each Mac. Not only is this an inexpensive option; but look at the alternative. One EHD with Time Machine backups from two Macs. Drive fails - they all do eventually - you've lost both Time Machine backups from both computers.

    The choice is, obviously, yours; but maybe rethink the consequences?

    Ian
    Ian

  3. #3
    Backing up Time Machine using another Time Machine
    ferrarr's Avatar
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    You could partition the second external, and use Time Machine for one partition, and a clone for the second partition
    -- Bob --
    Please backup. Everything has a life cycle, unexpected and warning free. Nothing will last as long as you want it to.

  4. #4
    Backing up Time Machine using another Time Machine
    Slydude's Avatar
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    @Porthoss Are you trying to have two different Time Machine backups, from two different Macs, on the same backup drive? If so member ferrar has provided an easy way to accomplish that. Partitioning the drie into two parts with one backup on each partition should work. I must issue the following warning or caution though:

    Any arrangement where you put the backups for two differnt Macs on the same hard drive could result in you loosing both backups. If the drive fails you could lose the backups for both Macs. ​/Picture arms flailig wildly and loud robot voice screeching a warning.

  5. #5
    Backing up Time Machine using another Time Machine
    ferrarr's Avatar
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    Quote Originally Posted by Slydude View Post
    @Porthoss Are you trying to have two different Time Machine backups, from two different Macs, on the same backup drive? If so member ferrar has provided an easy way to accomplish that. Partitioning the drie into two parts with one backup on each partition should work. I must issue the following warning or caution though:

    Any arrangement where you put the backups for two differnt Macs on the same hard drive could result in you loosing both backups. If the drive fails you could lose the backups for both Macs. ​/Picture arms flailig wildly and loud robot voice screeching a warning.
    I "think" one of the two backups, is a backup of a backup. So, they would only lose one of the backups. At least, that was how I read it.
    -- Bob --
    Please backup. Everything has a life cycle, unexpected and warning free. Nothing will last as long as you want it to.

  6. #6
    Backing up Time Machine using another Time Machine
    Slydude's Avatar
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    When I initially read this thread I thought as you do that the OP was looking to create a backup of a backup.When I read it the second time I wasn't sure. Let's assume that you're correct. Having a backup of a backup is a good idea but having the two backups on the same drive isn'y a good idea. In effect what you have is one backup because they are on the same drive.

  7. #7
    Backing up Time Machine using another Time Machine
    ferrarr's Avatar
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    Quote Originally Posted by Slydude View Post
    When I initially read this thread I thought as you do that the OP was looking to create a backup of a backup.When I read it the second time I wasn't sure. Let's assume that you're correct. Having a backup of a backup is a good idea but having the two backups on the same drive isn'y a good idea. In effect what you have is one backup because they are on the same drive.
    The way I see it is, a backup is only a backup. More is NEVER a bad thing.
    -- Bob --
    Please backup. Everything has a life cycle, unexpected and warning free. Nothing will last as long as you want it to.

  8. #8
    Backing up Time Machine using another Time Machine
    IWT's Avatar
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    Bob, you're right - the more BUs the better; but surely not if they are all on the same EHD.

    In my Post #2, I rightly or wrongly assumed that the OP wanted eventually to end up with 2 different BUs on the same EHD and I advised that EHDs are cheap whilst data is not; and that every individual BU should have its own EHD

    It may be that the OP wants a duplicate of another BU on the same EHD as a different BU. That's fine.

    I still struggle with the reluctance of some folks to invest a modest sum in a bunch of EHDs - say, 2 Time Machine, one or more bootable cloned BUs - protecting data on potentially thousands of pounds/dollars/whatever of computer hardware.

    Ian
    Ian

  9. #9
    Hi,

    First off, thank you for the welcome and thank you so much for your replies, I wasn't expecting any as my question was a bit odd. Sorry for the delay in replying I've had a couple of busy days.

    I should probably explain what I was thinking when I asked the original question, this is all based around being a bit paranoid of losing my data. I have a cheese grater Mac Pro that is at an office I rent. It has a dedicated 4TB TM drive fitted internally that I back up everything to. I then have a 4TB portable drive that I use as a 2nd TM backup that I then bring home with me in case someone broke in to the office or there was a fire etc. So I have the original data and 2 backups (one kept offsite) which is probably enough for most people.

    What I then started thinking was that when I took the portable drive to the office, all of my backups and the original data is all in the same place, at the same time (which worried me a bit). So I thought I'd buy another drive (as they are so cheap nowadays) that I could keep at home which could then be a clone of the portable 4TB portable drive. I appreciate it's overkill but the data means a lot to me. When I went to buy the new drive I got an 8TB desktop one. I then thought of how I could use the extra drive space instead of it only ever being able to store the same 4TBs of data from the portable drive.

    Hopefully you're still with me...

    So what I wanted to do was plug the 8TB home drive and the 4TB portable drive into my home laptop (which doesn't really have anything that important stored on it) and use the TM on the 8TB to backup the 4TB drive as if it was just a normal drive attached. That way, when my 4TB starts to overwrite the oldest TM backups, my 8TB doesn't and still has them saved.

    I hope that makes sense.

    Although, now I've written it all out it does seem like I'm trying to complicate things more than they need to be. It might be best to partition the drive and have a smart (updatable) Superduper clone of the 4TB drive instead and use the extra space for something else (as already suggested).

    Thanks again for your replies, I do really appreciate you taking your time to help.

    Ta
    J

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