Time Machine - does it erase other data on an external drive?

HungarianStan · Jul 29, 2015

So, finally bought the wife and me a 1TB external drive, since she's soon going to retire her old computer and get a new one. Also, this let me back up some data. Despite putting all our music, movies, documents, etc, on the drive, we only used about 140 GB. So, lots of space.

This has me thinking to do a TM backup on that drive, just to have one, but I don't want to do it if it'll erase the data on the external (it took my wife a LONG time to transfer things; the external has USB 3.0, but my wife's machine is old enough that I'm pretty sure it has USB 1.0).

Anyway, yeah, that's the question. If I do a TM backup on the drive, will it erase what's already been put there? Also, how much space will it actually take? Eventually, my daughter will put her stuff on the external as well, which would add up to 200GB total (possibly a little more). So there has to be space for that. And whatever else we might stick there at some point.

I should add, I'm using a Mac, and my wife and daughter are using Windows machines.

IWT · Jul 29, 2015

Hi Mencelus

There's a lot of incompatibilities here which need sorting out.

Firstly, I would never recommend sharing a TM backup on an EHD with anything else. But if you did, then in your particular case, there would be problems. TM requires an EHD formatted in Mac OS Extended (Journaled). You tell us that your wife & daughter have been backing up their Windows data to the EHD and would wish to do so in the future. This is incompatible the Mac Format needed for TM.

So, in response to one part of your question, to use TM, you would need to reformat and, yes, the data on the EHD would be lost.

Taking your whole post and my initial comments, this is how I would advise you:

1. Some form of BU is really essential and TM is a good starting point.
2. But use a separate EHD for TM, formatted OS Extended (Journaled)
3. Your wife & daughter should keep any BUs on a separate EHD formatted for Windows
4. EHDs are very cheap nowadays, certainly in comparison with computers and the tragedy of losing precious and vital data plus the enormous expense of trying to retrieve same.

I think that covers most of what you posted, but please post back any further queries.

Ian

HungarianStan · Jul 29, 2015

IWT said:
Hi Mencelus

There's a lot of incompatibilities here which need sorting out.

Firstly, I would never recommend sharing a TM backup on an EHD with anything else. But if you did, then in your particular case, there would be problems. TM requires an EHD formatted in Mac OS Extended (Journaled). You tell us that your wife & daughter have been backing up their Windows data to the EHD and would wish to do so in the future. This is incompatible the Mac Format needed for TM.

So, in response to one part of your question, to use TM, you would need to reformat and, yes, the data on the EHD would be lost.

Taking your whole post and my initial comments, this is how I would advise you:

1. Some form of BU is really essential and TM is a good starting point.
2. But use a separate EHD for TM, formatted OS Extended (Journaled)
3. Your wife & daughter should keep any BUs on a separate EHD formatted for Windows
4. EHDs are very cheap nowadays, certainly in comparison with computers and the tragedy of losing precious and vital data plus the enormous expense of trying to retrieve same.

I think that covers most of what you posted, but please post back any further queries.

Ian

The formatting thing is exactly what I didn't know (and now that you say it, seems obvious). Thanks a lot of the info! Actually, I'll have to pop for another drive at some point then, I guess. They are "cheap", as you say, for various interpretations of such.

Rod · Jul 29, 2015

Hi Mencelus, do I understand you correctly that both you and your wife have already added data to this external HD? Does this mean you have a Mac and she has a PC?
If you bought a Ext HD off the rack then it is probably already formatted for Windows. This is good for your wife but not so good for you. Although a Mac can read a windows formatted drive it is not a good idea for archiving in the long term.
As for your wife there is a windows native program called called Backup an Restore. Although it is different in operation it is essentially the same idea as Time machine only for PC's.See here. Backup and Restore - Microsoft Windows

IWT · Jul 29, 2015

Excellent points, Rod, as always.

I took this into account in my reply as the OP said:

I should add, I'm using a Mac, and my wife and daughter are using Windows machines.

I've advised, like you I think, that they should keep the Mac and Windows' BUs quite separate in view of the formatting differences. Would you agree in principle with my posting (#2 above)?

Ian

toMACsh · Jul 29, 2015

Not sure if this will help the OP's situation, as I have only a single Mac, and no network. (OP must have a network to use one external for Mac and Windows PCs, right?) I purchased a 2TB external, thinking ahead a little. I then partitioned it and use one of the partitions for TM backups. If the OP is going to reformat, that would be a good time to partition, if that would be beneficial.

Rod · Jul 31, 2015

Partitions are a good idea. I have a similar portable EHD with TM on one partition and CCC on the other.

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