backupencryptiontime-machine
I have set up a 4TB external USB drive to use as a backup for my 2TB MacBook Pro. Everything seems to work all right, but the encryption takes forever, and the Time Machine insists on it being performed only when the computer is plugged in into a power outlet.
Since I would like to use my laptop as intended (as a portable computer), what can possibly go wrong, if I disconnect the backup drive, while it is still encrypting its contents?
I am running the latest Sierra on the 2016 MacBook Pro.
Your preferred setup is not possible: OS X can't share an NTFS disk with Windows for backup because Time Machine needs HFS+ (from http://support.apple.com/kb/HT1427):
Manually preparing a new disk for Time Machine
(...)
If you want to partition the disk, click the Partition tab and select a layout. Make sure "Mac OS Extended (Journaled)" is selected in the Format menu for the partition that will be used for backups. Click Apply.
Luckily, you don't need two separate drives. Using partitioning you can trick your computer into thinking it is connected to more than one drive, although there's only one. In this case, two partitions will suffice, one HFS+ and one NTFS.
(Why only one NTFS partition although you back up 3 Windows computers? Because Windows stores backups in folders named after the computer name so there are no conflicts whatsoever (see this post). You can use one NTFS partition to store backups of multiple Windows computers.)
I'd recommend that you create the HFS+ partition on your Mac first, then, on your Windows computer, format the other partition to NTFS:
When you're done, plug the drive again into every Mac/Windows computer and select the corresponding partition as backup drive (see here for OS X and here for Windows).
To prevent the NTFS partition from being mounted every time you connect the drive into your Mac add this entry to /etc/fstab (as explained here):
LABEL=BACKUP_WINDOWS none fusefs_txantfs noauto
Replace BACKUP_WINDOWS with the NTFS partition name.
This setup works like a charm.
I have a very similar configuration:
My external 1 TB drive, which I use for backing up my Mac and my wife's Windows PC, has two partitions called "Time Machine" and "BACKUP_WINDOWS":
You probably want to check out this website for the most information, but here is the answer to your question, quoted from the website above:
A general "rule of thumb" is, to keep a reasonable "depth" of backups, Time Machine needs 2 to 4 times as much space as the data it's backing-up (not necessarily the entire size of your internal HD). Be sure to add the size of the data on any other drives/partitions you want to back up.
But this varies greatly, depending on how you use your Mac. If you frequently add/update lots of large files, then even 5 times may not be enough. If you're a light user, you might be able to get 1.5 times to work, but that's subject to problems any time a large backup is needed.
And, of course, the larger the drive, the more old backups Time Machine can keep for you. A drive that's too small may only have room for a few weeks (or even days) of backups.
Unfortunately, it's rather hard to predict, and most of us have a tendency to add more and more data to our systems over time, so if in doubt, get a bigger one than you think you need now.
Also, there are some OSX features and 3rd-party applications that take up large amounts of backup space, for various reasons. See question 9 for details.
This is a trade-off between space and how long Time Machine can keep its backups, since it will, by design, eventually use all the space available. But it won't just quit backing-up when it runs out: it starts deleting the oldest backups so it can keep making new ones. Thus, the more space it has, the longer it can keep your backups.
If your backup disk is on the small side, and Time Machine needs to do a very large backup, either because you've added or changed a lot or done something like an OSX update since the previous backup, you may get one of the messages in Troubleshooting item #C4 (which one depends on exactly what happened, and which version of OSX you're on.)
Then it'll only take a snapshot that's about 120GB in size, and while that same snapshot will grow over time as I take more recent snapshots of my system, it will never go beyond 500GB because that's the maximum size of my internal HDD.
No, not quite. The 1 TB hard drive will be filled up because Time Machine keeps your backups and deletes them once your hard drive is filled. There is more than one backup stored on that hard drive. As stuffe pointed out as well, Time Machine allows you to restore to a previous backup, since Time Machine may keep 7 or 8 backups on that 1 TB hard drive.
I'm asking this because I want to know if I should use a separate external HDD for storing my actual files.
Yes, you should. You should be dedicating a drive to Time Machine. Here is the quoted answer from 3 in the website I linked above:
Yes. Time Machine will not delete anything you put there. But it's not a good idea to put anything else important on the same physical drive, unless you back it up elsewhere. When (not if) that drive fails, you risk losing it.
If you want to do this anyway, it's much, much better to partition an external drive into 2 (or more) parts, also called volumes. Assign one to Time Machine, for its exclusive use for backups; use the other partition(s) however you want. To use a new drive, or one you don't mind erasing, see question #5. To add a partition to an existing drive that already has data on it, see question #6.
Best Answer
After encrypting the drive for a few days (while the drive was disconnected a few times, and then connected again), Time Machine has finally finished with it and now only runs backups. Nothing indicates a problem, so I think it was all right--the encryption would pick up at the same percentage it was when disconnected, and continue, until done.