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

@Pondini

Pondini wrote:

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.

The description of what color the files are was helpful, but I'm still not able to find a solution. I have a hard drive on a newer Macbook in Target Disk Mode, going to an older but updated MacBook Pro, which has an external hard drive attached. The external hard drive is where I want the back up to go, but the hard drive for the Macbook that is in TDM is showing as a "gray" as another external drive, which I find hard to believe isn't formatted for Mac since it is a mac. How do I use the time Machine to make a backup of the TDM connected drive into the external drive? BTW, this all happened as well as all my photo libraries corrupted after downloading El Capitan (black screen with white apple logo and never moving bar is what prompted me to try this method). Thanks!

Like you, 7string48, I also worked for decades in a large mainframe/mini IT situation, and was involved with backup situations.

Yes, it's true! Time Machine will back up almost any and all external hard drives that you have connected into your Mac.

As far as Drobo hard drives not being able to be backed up by Time Machine, I'd like to pass along my good experience:

I have a 5 TB Seagate Backup Plus drive for the Time Machine hard drive.

It backs up both my iMac 1 TB (with Fusion drive also), and any/all of my external drives that I choose, as explained above by Keg55 and Pondini. Easy.

Also, instead of Drobo, I use OWC external drives, and they work fine.

My main external drive is an OWC Thunderbay 4 Raid5 (which is four 3TB drives, functioning in a Raid 5 configuration).

I keep all my video and photos and many Adobe Premiere and Final Cut Pro X libraries on it -- Time Machine backs it up just great! Using the "exclude these items from backup" on the Time Machine window Keg55 showed, I typed in the full pathname on that Raid5 drive of several Adobe and Final Cut temporary cache directories that don't need to be backed up, and they are excluded from the Time Machine backup. And I've also been able to easily restore files using Time Machine Restore, back to any of my external drives.

Hi Thanks for the input. As it turns out I had brought my MAC in to Apple for some issues and when Apple upgraded to the new OS I had more and different issues, one being the backup. They apparently performed some 'magic' and behold everything now works as advertised!!

Thanks again for a timely response

And, remember everyone, you can, with Time Machine,

Back up EVERY hard drive in your Mac, and connected to your Mac, as long as it is formatted Mac, as Pondini posted above.

Just click on the Time Machine "Options" button, and in the Exclude list showing your external hard drives, click on one of them, then click on the minus-sign "-" down below, to take it out of the Exclude list. Then click on another, etc.

And, since you might fill up your Time Machine hard drive, backing up too much to it, you then can EXCLUDE folders on any internal or external drive from being backed up.

Just click on the Time Machine "Options" button, and in the Exclude list, type the full path name of the folder you want to exclude from being backed up,

like for example:

/volumes/mydisk1/FinalCut Cache/

/volumes/mydisk2/YouTube Downloads/

I'm going to now look into getting a huge 20 terabyte Raid 5 (gives redundant data protection), for my Time Machine Backup drive, from OWC for my iMac, because I have so many videos and photos, Adobe and Final Cut projects, starting from 60 years ago... 🙂

correction ... in the Exclude list, to add something to the exclude list, you can just click on the plus-sign + at the bottom, then choose which folder you want to add to the list. Don't need to type it in yourself. See pondini.org for all the details! FAQ # 10 there... http://pondini.org/TM/10.html

A great web site for Apple and Time machine. Thanks, Pondini!

Hi Pondini and others, thank you for very useful posts.

I do Time Machine backups to several different hard drives (backups every night to a Time Capsule, and to a USB disk, and in addition manually initiated backups to a couple of hard drives that I rotate between home and work).

Everything is running as smooth as can be expected. However, my photo library is growing rather quickly, and I recently moved all media files to an external drive. This drive has not been included in my TM backups so far. I only want these files backed up to the drives I keep offsite because of space constraints, we have several Macs backing up to the TC and I also backup other macs to the USB drive.

In this context I have a question that is related with the original question in this thread: can I specify different external drives to be included for each TM backup disk? I realize I can include the media drive manually when I backup to the drives I keep offsite, but would prefer to have that done automatically if possible.

It will not allow me to select my portable drive and back it up in time machine. How do I make this happen?

Is it formatted for Mac, as Keg55 mentioned here and Pondini wrote about here?

Yes, do what others say about making sure your external harddrive is NOT on the Time Machine excluded list. However, initially that was not working for me, so what I figured out is that you have to format your hard drive for Mac first. Then you can exclude it. Here is the link to how I did this:

http://knowledge.seagate.com/articles/en_US/FAQ/007736en

Thanks Pondini, for all the very useful tips on the TM operations.

I have a slight variation to a topic discussed as far back as 2012, but can't find a similar Q/R. I have a Transcend Jetdrive lite 256GB in my MacAir (in the SD card slot), and it works and shows up just like an external HD. But when trying to run a backup on this in TM, I can only see it in the Options as a gray item. Strangely enough, I can "exclude" files from it (using the - sign), and they also show up in gray, but I can't select and therefore add the Transcend drive to the backup.

As you said before, this may be since it's not formatted with the correct Mac format, but not sure I can/should re-format this given it sits in the SD slot and might have a particular formatting. But given these are specifically made/sold for Macbooks, seems strange that it wouldn't be formatted that way?

Any options or suggestions what to do?

Thanks a lot!

HI, I have been using Time Machine to back up both my MB air and an external drive for just over a year, always believing everything was OK. i decided to test a recovery from my time machine backup without the external drive mounted. When exploring a backup only performed a couple of days ago (that had the external drive included) I couldn't see any files from the external drive or indeed the external drive itself. This seems to indicate that any restore would need to have the external drive connected, which seems odd given one purpose of the backup is to protect against HDD failure.

I have checked to ensure I am backing up exactly as per your instruction Pondini, am I doing something wrong from the restore perspective or missing some other info required to ensure Time Machine functions correctly?

Many thanks

Hi I can't see it even in gray! Are you sure that's the case?

I have an external drive attached to my TC.

My MBA can see this external drive and access it fine.

But the Time Machine doesn't see it.

Ideas why-- Anyone??

You can use Disk Utility to erase and partition an SD card drive to MacOS extended, and then it will be a candidate for Time Machine Backup.

Erasing or re-partitioning any drive deletes all its files.

SD cards are drives like so many others, but are often shipped form the manufacturer in Windows formats.

Hi! I'm looking to back up an external hdd too. But I have a slightly different issue. See, my macbook is way overloaded, and most of it, like 600gb is my iTunes library. I read all about how to migrate it over to an external hdd and how to get iTunes to find it, but I'm worried about backing it up.

I use a time capsule, and I love it. I want to put the external hdd with the iTunes library on the usb port on the time capsule so that it is available all the time, no matter where I am in the house. But I also want to back it up.

Can I back up an external HDD that is attached to the time capsule using time machine like I do my Macbook?

I don't want to copy it all across and risk losing it all just to try it out. I'm not even sure I should be doing it without competent supervision, but I'm the only person I know who uses apple products, so I'm on my own with this :/ Any help will be greatly appreciated!!

Thanks in advance and hugs to everyone!!

I have 2 Seagate external hard drives attached to my Mac, one for backup and one for my pics and music. I would like to back up the pics and music onto the backup drive. In Time Machine Preferences>options, I see the pics and music disk in black, I select it and click the minus sign but it does not back it up. It backs up something for a couple of megabytes then is done. When I pull up options again, the pics and music disk is there again in black.

There should be plenty of room. Could it be a partition issue? 😕

Thanks in advance.