Can I set Time Machine to backup both my hard drive and an external hard drive?

Not sure if you are still online keg55. I really appreciated the clarify of your answer to this question. I have additional questions which will reveal my beginner status: 1) When I remove an external hard drive from the exceptions list, will it continue to back up the internal hard drive, AND the external hard drive too? And, similar to some other questions that have been posted, 2) How do I check to see that the hard drive has actually been backed up? When one restores, does the hard drive have to be connected? What if the hard drive has gone missing or is other wise not available? Do you just give the new replacement drive the same name? Thanks!

Use these articles from Pondini's site:

14. How do I restore my entire system?

15A How do I use the (not so intuitive) Time Machine display?

15. How do I view or restore selected items?

16. How can I restore a file/folder to an alternate location?

the items above have been turned into "live" links to their appropriate pages.

A Source Drive (to be backed up) must be a MacOS HFS+ format drive. This is because Time Machine relies on the Mac 'File System Event Store' to see what folders have changed. This is described in a bit more detail in part 1 of this 5 part illustrated article:

.Pondini's -- How Time Machine Works its Magic

.

Time machine can only be set to back up ONE selected harddrive, usually, though not always, the internal one.

Hope this helps 🙂

Yes, you can backup you internal partitions and external partitions using TM. You can only Select one drive to backup to, but in the Options button you can remove any exclusions from the Exclude list and TM will back them up.

In the screenshot below, I can't backup the partition I'm backing up to (Mac Mini TM) or the NTFS partition (WIN BACKUP), but I can backup the other external partition (Mac Mini Backup) by removing it from the Exclude list.

You should be able to back up any external HD, if it's formatted for a Mac.

By default, all externals are excluded and shown in the exclusion list in Time Machine Preferences > Options, as shown in keg55's post.

If you see it there, in black, just select it and click the minus sign at the bottom.

If you see it in gray, that means it's not formatted for a Mac, and Time Machine can't back it up. You'll have to copy the data elsewhere temporarily, reformat the drive (perTime Machine - Frequently Asked Question #5), then remove it from the exclusion list.

Thanks so much Pondini!! You just quickly answered a question that none of the Mac people in 3 stores or Apple Care have been able to answer. I am moving from PC and wanted to setup backups for large external drive with lots of photos, and the Mac reps either said they didn't know, or you can't do that. One person said I could but was unable to explain how. Thanks!! I had tried connecting an external drive, but it was not formatted for Mac, so that was the key piece of missing information.

Oh...what about if the external drive is an array...like a Drobo with it's own proprietary formatting...I guess that would not work...??

7string48 wrote:

Thanks so much Pondini!! You just quickly answered a question that none of the Mac people in 3 stores or Apple Care have been able to answer.If you can format it HFS+ (any variation of Mac OS Extended), it will work. If not, it won't.

I'm not too surprised about the Apple Stores, as they don't get much training on Time Machine. But AppleCare sure ought to know.

Oh...what about if the external drive is an array...like a Drobo with it's own proprietary formatting...I guess that would not work...??

I've never used a Drobo. A number of folks here have used them as their Time Machine drives, but I don't recall seeing anyone try to back one up with TM, so can't say for sure. But if you can format it as HFS+ (any variation of Mac OS Extended), it will work. If not, it won't.

At least part of the reason is, Time Machine uses the File System Event Store, a hidden log of changes that OSX keeps on each Mac-formatted disk/partition, to figure out what's changed and needs to be backed-up. See How Time Machine works its Magic for details.

See Time Machine - Frequently Asked Question #32 for details and considerations of backing-up multiple volumes with Time Machine.

However, even if it will work, that may not be your best strategy, depending on your circumstances:

Since Time Machine keeps copies of things you've changed or deleted, the destination needs to be considerably larger than the data being backed-up. How much larger varies widely depending on how you use your Mac, but a general "rule of thumb" is, it needs at least twice the space to be able to keep a reasonable "depth" of backups for you.

If you have a large internal HD, fairly full, plus a large external HD, and the files on the external don't change frequently, you might want to use Time Machine for the internal, and a different app to a different disk or partition, on a different schedule, for the external. Especially if space is a consideration, you might not need to keep previous versions of files on the externals. See Time Machine - Frequently Asked Question #27 for some alternatives.

I have been reading the articles on your website, and they are extremely informative! Exactly the kind of detail I need myself to understand enough about the architecture to make intelligent decisions on backup strategy. I come from large mainframe IT shop background myself and was heavily involved in large volume database backups, so I really like to understand the details, and I really appreciate you sharing info that the Apple team either does not know, or does not want to share as openly...they seem to be intent on keeping everything simple...which is generally good, but sometimes dumbs it down too much for me.

I did speak with a very helpful lady in the Drobo pre-sales team, and she indicated Drobo could not be backed up via Time Machine due to the Drobo proprietary architecture. But they do seem to be perhaps the best scalable volume backup destination for home/small business. They just released their new Thunderbolt 5 bay Drobo 5D for pre-order today, so I will give that serious consideration as a TM backup destination. What I like is the flexibility to add different drives of different sizes and even different manufacturers, and they will now support both HDD and SSD, so a completely scalable solution as backup needs grow. They can be used as a primary drive, but then she recommended using something like Carbon Copy Cloner which you recommended...but I have not verified that would work with Drobo either. Oh...and she said that her personal setup at home was to run a Mac mini directly connected to the router and Drobo so that you had the option of either backing up to the Drobo via wireless over your home network, or directly attached for initial backup or when you know there will be a large volume of changes to be backed up.

Another service I want to explore is Crashplan online backups. A friend who works at Google recommended it because it allows you to send them a hard drive to seed the backup so you don't have problems with a large initial backup over the internet...and which would exceed the monthly limits of my internet provider.

Thanks again!

Thumbs up for this! Just set up older MacBookPro to be a music center with iTunes on external HD. Happily backing up now to my airport mounted backup drive.

Awesome info from Pondini - thank you!

You're amazing! Thanks so much for posting this.

I've been asking my techy friends for YEARS now if this was possible, and shockingly they always told me it wasn't. I never understood why.

I just got a Synology Disk Station (2 x 3TB mirrored) and have used Time Machine to wirelessly backup 3 macbooks to that, but since I didn't think using TM for an external drive in addition to the internal, I ended up just "copying" the contents of that external drive onto the Synolgy in it's own folder.

I was really not looking forward to having to re-copy the entire contents every week, just to make sure I got any updated data/changes that may have been made.

I decided to give it one last go on google to see if anyone had posted how to do it (previous searches turned up nothing), and boom I find your answer.

Now everything will back up seamlessly using TM. 3 macbook hard drives + an external, all to the Synology Disk Station.

Setup is officially golden. So stoked!

Thanks again for posting your answer and screengrab!

Just wanted to say Thanks,

Having recently bought the new AirPort Time capsule and the LaCie Rugged 2TB, I was getting a bit miffed at seeing all of the negative posts regarding the Time capsules. With a bit of time / some perseverance and good sound advice from the likes of yourself and Linc I am starting to reap the rewards of knowing. . . Not only does it work - it works very well.

I have recently migrated from Win 7 machines (well i use bootcamp to run Revit and CS suite) but am loving OS 10.10 and all the included apps, switched to Pages & Numbers and just in awe of the quality of the apple build - both hard and soft.

I suffered two HD failures in succession about a year apart and the constant plague of windows issues, well everything goes with time. . . I Just suppose i'm in that honeymoon period, but I can see this one being a keeper.

Cheers guys, to all of you on the support forums and apple, this is a good place to be.

When I open the options window to exclude the external drive, it is greyed out and cant be removed. Any thoughts?

Any help would be appreciated.