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Best Way to Format Time Machine Drive?

What's the best way to format/encrypt your Time Machine drives with Big Sur now?

  • (1) Format APFS, then in time machine preferences select encrypt

    Votes: 7 50.0%

  • (2) Format APFS encrypted, then just back up via time machine preferences

    Votes: 2 14.3%

  • (3) Format APFS case sensitive, then in time machine preferences select encrypt

    Votes: 1 7.1%

  • (4) Format APFS encrypted/case sensitive, then just back up via time machine preferences

    Votes: 2 14.3%

  • (5) Other (please explain)

    Votes: 2 14.3%
  • Total voters
    14
ZombiePhysicist

ZombiePhysicist

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Original poster
May 22, 2014
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Which is best way to format the time machine drive now with Big Sur supporting APFS?

I used to format my drive as HFS encrypted and then select it in Time Machine preferences to back up onto.

But there may be like 3 or more permutations to use TimeMachine now, and I want to select the option that is most native to TimeMachine, i.e., fastest and most secure.

Options:

(1) Format APFS, then in time machine preferences select encrypt
(2) Format APFS encrypted, then just back up via time machine preferences
(3) Format APFS case sensitive, then in time machine preferences select encrypt
(4) Format APFS encrypted/case sensitive, then just back up via time machine preferences

Normally I wouldn't touch case sensitive with a 100ft pole as it generally only causes incompatibilities (Adobe apps break with case sensitive file systems).

However, I noticed when I made a new backup to my Synology server with TimeMachine, and I checked on the sparse bundle it created on the network Synology drive, it created an APFS case sensitive container. Weirdly, it doesn't say APFS encrypted and case sensitive, just APFS case sensitive.

So what say you all? What's the best way to format your Time Machine drives now? Take the poll and please comment on any of your thinking.
 
Quackers said:
Pretty sure if you go with APFS TM will change it to APFS case sensitive on its own.
Click to expand...

So is that youre sense. Just format plane Jane APFS. Then flip the encrypt switch in the Time Machine pref panel when you set it up, and 'use the force' to trust apple will 'do the right thing' to the drive/container in the background (i.e., option 1)?
 
Quackers said:
That's what it did for me :)
I didn't go with encrypted.
Click to expand...
Did you hit the 'encrypt' option in the Time Machine panel, or is yours completely not encrypted.

But it's interesting, you formatted straight APFS on a local drive, and after running time machine, it now says APFS case sensitive?
 
So this is interesting. I formatted the drive as APFS encrypted, and when started time machine, it changed the container format to APFS encrypted, case-sensitive.

Then, I tried formatting the machine just as APFS, and selected to encrypt via the TimeMachine system prefs panel, and it also converted the volume to APFS encrypted, case sensitive.

So TimeMachine seems to work differently when you backup locally vs on the network. On the network, it changes the sparse bundle to be APFS case sensitive, but NOT encrypted, but still shows via the system preferences that the data is encrypted (which is somewhat worrying).

While, on the local drive, it basically doesn't matter what options you select, it will change the volume to be APFS case sensitive, and if you enable encryption, it will be APFS case sensitive, encryption. If you watch Disk Utility while Time Machine works, you see it nukes the old volume and creates a replacement new volume with the right formatting.

I wonder if this makes a difference performance-wise somehow. I know I generally feel safer having the entire drive encrypted from the get go, rather than just some volume on it, so that's what I'm going to do regardless. But seems like you get to the same place for local Backups.

Not sure why the network volume only shows APFS case sensitive formatting without encryption despite time machine showing the backup is encrypted...
 
Last edited:
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ZombiePhysicist said:
So TimeMachine seems to work differently when you backup locally vs on the network. On the network, it changes the sparse bundle to be APFS case sensitive, but NOT encrypted, but still shows via the system preferences that the data is encrypted (which is somewhat worrying).
Click to expand...
That's not a characteristic of Time Machine but of image files. It's the image file (spare bundle or other forms) that is encrypted as a container independent of the disk format or filesystem used inside the image, so the filesystem inside the encrypted image will always be unencrypted. Otherwise it'd be redundant and unnecessary overhead, encrypting what's already encrypted. You can see it in Disk Utility when you create an image file.
 
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So a follow up. The performance with APFS being done under 11.01 vs 11.1 is NIGHT AND DAY. So while formatting and using APFS worked under 11.01 it really was no faster. It still used the old style of backup, just with a new file system. I have about 11TB of data that gets backed up with time machine and it could take around 1hour to back up just a 1-7GB of delta data.

Now, backing up on the Synology completes in 4minutes, and on the local drive in 1minute for the same delta! IT IS INCREDIBLE.

Also, when you look in the local time machine, you now see, in the root, a ton of snapshot folders. It looks like a completely different structure than was happening with 11.01 (or earlier versions of macOS).

So, if you bothered to turn on APFS in macOS 11.01 Big Sur, I hate to tell you, you should nuke them and start over fresh in 11.1. It is an incredible difference in efficiency.

As always, YMMV.
 
ZombiePhysicist said:
So a follow up. The performance with APFS being done under 11.01 vs 11.1 is NIGHT AND DAY. So while formatting and using APFS worked under 11.01 it really was no faster. It still used the old style of backup, just with a new file system. I have about 11TB of data that gets backed up with time machine and it could take around 1hour to back up just a 1-7GB of delta data.

Now, backing up on the Synology completes in 4minutes, and on the local drive in 1minute for the same delta! IT IS INCREDIBLE.

Also, when you look in the local time machine, you now see, in the root, a ton of snapshot folders. It looks like a completely different structure than was happening with 11.01 (or earlier versions of macOS).

So, if you bothered to turn on APFS in macOS 11.01 Big Sur, I hate to tell you, you should nuke them and start over fresh in 11.1. It is an incredible difference in efficiency.

As always, YMMV.
Click to expand...
Very interesting. May I ask how your mac connects to your nas, wifi or ethernet?
 
JimmyjamesEU said:
Ahh ok thanks. I'm trying on wifi and it's slooowww!
Click to expand...
To be honest, not much faster.

So pure raw read writes over 10GB runs around 925MB/sec to the Synology.
But time machine wimps out at around 130MB/sec one the network.
It does maybe around the same on a local drive.
WiFi I get around 55MB/sec.

So something about how time machine is probably encrypting data it is sending over the network or local drive slows it down.

The local drive I do see 250MB/sec (the max speed of the single local drive) on the very first backup. But after that, its around the same speeds.

Most of the time Time Machine spends on scanning and doing little file updates, which have more latency on the network mounted drives than the local drive. So it's not the throughput so much as the latency that seems to kill time machine performance for me (again, with the exception of the very first large backup).

One of the many mysteries of time machine!
 
ZombiePhysicist said:
To be honest, not much faster.

So pure raw read writes over 10GB runs around 925MB/sec to the Synology.
But time machine wimps out at around 130MB/sec one the network.
It does maybe around the same on a local drive.
WiFi I get around 55MB/sec.

So something about how time machine is probably encrypting data it is sending over the network or local drive slows it down.

The local drive I do see 250MB/sec (the max speed of the single local drive) on the very first backup. But after that, its around the same speeds.

Most of the time Time Machine spends on scanning and doing little file updates, which have more latency on the network mounted drives than the local drive. So it's not the throughput so much as the latency that seems to kill time machine performance for me (again, with the exception of the very first large backup).

One of the many mysteries of time machine!
Click to expand...
Interesting. 130MB sounds like the limits of a hdd or a group in a parity raid setup. The most frustrating thing is the wifi backup has periods where it's 40-50MB/s but then long periods of 2-3MB/s. To a local disk it is able to pretty much max out the disk speed.
 
JimmyjamesEU said:
Interesting. 130MB sounds like the limits of a hdd or a group in a parity raid setup. The most frustrating thing is the wifi backup has periods where it's 40-50MB/s but then long periods of 2-3MB/s. To a local disk it is able to pretty much max out the disk speed.
Click to expand...
The limits of the raid on Synology are around 925MB/sec. So if just mount the Synology and copy/write a big file, that's what I get.

Yea, so whatever max peak throughput is seems to be irrelevant because Time Machine ratchets down to really slow rates for seemingly the vast majority of backups.
 
ZombiePhysicist said:
The limits of the raid on Synology are around 925MB/sec. So if just mount the Synology and copy/write a big file, that's what I get.

Yea, so whatever max peak throughput is seems to be irrelevant because Time Machine ratchets down to really slow rates for seemingly the vast majority of backups.
Click to expand...
Ahh I see. That is curious. Then I wonder if there is an issue writing to a disk image at high speed.
 
What are the differences between encrypting the disk versus selecting encryption in Time Machine?
 
wellander1 said:
Use other backup methods.
Click to expand...
Why though? I get that any one backup method is not enough, but there's absolutely nothing wrong with having a system that automatically saves snapshots of changed files every hour. Time Machine has saved my ass on many occasions, and I've also migrated to new Macs with it several times and it's worked wonderfully.

Stuff like Carbon Copy Cloner is awesome. I use it to create offsite backups and I used it to clone a drive to later install into my iMac -- but they're not exclusive methods and you can't beat Time Machine for simplicity.
 
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