Announcement: Upgrade to macOS Mojave

With features like Dark Mode, Stacks, and four new built-in apps, macOS Mojave helps you get more out of every click. 
Find out how to upgrade to macOS Mojave > https://support.apple.com/macos/mojave

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Question:

Question: Time Machine backup of an external disk....?

Wondering how Time Machine handles if, except for the iMac's internal macOS disk, also an external disk is in the backup list? It seems to me that the macOS disk is being backup incrementally but that the external disk is being fully backed up each time... so no increments but full backup each time.

Is that observation correct? In that case why is that; it fills up backup space very fast of course?


iMac 27inch(late 2012) macOS 10.13.1, Fusion 1Tb macOs disk, 3Tb Lacie usb3 disk

iMac (27-inch, Late 2012), OS X Mountain Lion (10.8.5)

Posted on

Reply

Page content loaded

Nov 16, 2017 9:23 AM in response to John Galt In response to John Galt

Thanks for your answer John! The external disk essentially contains my photo-library being 600Gb of folders with Raw/CR2 files in it. Also some libraries with MP4 video. The iMac internal disk contains Adobe Lightroom catalogs and other work-files, miscellaneous folders with normal stuff being documents, email, iTunes music and films. All pretty important to have a decent backup! :-)

Nov 16, 2017 9:23 AM

Reply Helpful

Nov 16, 2017 9:29 AM in response to polimo In response to polimo

It will be backed up. Confirm that it is not excluded from being backed up in Time Machine's Preferences... > Options.


It's always a good idea to have more than just one backup too. A catastrophic event (think electrical or environmental catastrophes) could conceivably destroy both a Mac and everything connected to it simultaneously. Don't ask me how I know.

Nov 16, 2017 9:29 AM

Reply Helpful

Nov 28, 2017 9:41 AM in response to Old Toad In response to Old Toad

Thanks for the info John, Old Toad!

It seems that as long as you make just one TM backup everything is under control: one full backup followed by hourly incremental backups of both disks(internal, external). But if I add a second backup disk to make a second backup, TM seems to not being able to cope with that. It starts doing multiple full backups of unchanged data of the external disk, which is not workable. So I am back to just one single TM-backup. I will have to do a second backup using other tools.

Nov 28, 2017 9:41 AM

Reply Helpful

Nov 28, 2017 9:52 AM in response to polimo In response to polimo

A smart, second backup would be a bootable clone of your boot drive with either Carbon Copy Cloner or SuperDuper. It could be updated once a week in the background as you work on your Mac. Both can do incremental backups, i.e. only copying those new or modified files.


This type of backup will let you boot from it in case your internal boot drive has problems and let you work on the internal boot drive. The external clone drive will be slower but lets you get back to work right away.

Nov 28, 2017 9:52 AM

Reply Helpful

Jan 2, 2018 3:31 AM in response to Old Toad In response to Old Toad

I organised meanwhile around a second backup with CCC; works perfect indeed! I also like the incremantel backup from CCC which seems to update the actual bootable backup image directly, it seems.

One question though... I also tried to boot from the bootable CCC backup, using a USB connected WD external disk, but that seems as good as unworkable because of the slow response of the USB disk. I suppose you need a faster connection to use it as a real boot backup. Would a Thunderbolt 2 or 3 connected drive solve that problem?? Any experiences?


Wisk you a strong 2018!!🙂

Jan 2, 2018 3:31 AM

Reply Helpful

Jan 2, 2018 2:23 PM in response to polimo In response to polimo

Yes. Anything is faster than USB 2. I sometimes boot from FW 800 external HD and it's workable but slow.


If you get a Thunderbird 2 or 3 drive you'll need a Thunderbird 2 or 3 port on your Mac. Do you have one. If you have USB 3 that is very fast if you have a similar external HD.

Jan 2, 2018 2:23 PM

Reply Helpful
User profile for user: polimo

Question: Time Machine backup of an external disk....?