Use APFS to Create Faster Time Machine Volumes

This week, I discovered a way to create faster and more flexible Time Machine backup volumes using APFS. But, first, some background.

Time Machine, the built-in backup utility for Macintosh computers, requires a separate drive for its files. If you only have the internal drive on your computer, Time Machine makes backups on your internal drive, which kinda defeats the purpose of backups.

There are a variety of backup options:

Personally, though, I don’t like storing my files in the cloud:

  1. Because it requires paying rent every month to store my files.
  2. There’s no guarantee of data security when storing files on the cloud.
  3. The privacy statement from companies like DropBox show far more data sharing than I’m comfortable with.
  4. Storing files locally isn’t that expensive and can be fully automated

Still, there’s no doubting the convenience of accessing your backups from anywhere when they are stored in the cloud. And, if you have a laptop, it’s reassuring to know that your system is backed up, even if you are traveling.


At its simplest, connect an inexpensive SSD to your computer and use that for Time Machine. For example, using a Samsung T-7 or T-9, the storage capacity ranges from 1 TB – 4 TB with prices from $110 – $350.

SSDs are dead quiet, small, rugged, connect via USB-A or USB-C, and are plug-n-play easy. The only problem is that they need to be permanently connected to your computer for Time Machine to access them, which means you have one less port available on your computer.


However, for those of us with SSDs or SSD RAIDs, there’s a better option. In the past, using HFS+, we would need to dedicate specific hardware to create a stand-alone volume for Time Machine to use.

NOTE: HFS+ should be used to format all hard disk drives (HDD) and HDD RAIDs. APFS should be used for all SSDs and SSD RAIDs.

However, APFS provides a much more efficient storage alternative: Container volumes. Rather than use dedicated hardware, you create flexible “partitions” in your existing storage.

When APFS formats a drive, it creates a master “Container,” within which are stored volumes, which you can think of as separate drives. By default, initial formatting creates a single volume which takes all the storage space on that device.

Most of the time, that single volume is all you need. Into that we create folders and store files, the same as any other drive.

However, you can create additional volumes at any time; for example to use for Time Machine, a different operating system, or data which needs encryption for extra security. These are not folders, but stand-alone volumes, separate one from the other.

The process to create these volumes is the same whether you have a single SSD or an SSD RAID.

Click to see larger image.

This is an 8-drive Thunderblade 8 RAID, loaned to me for review by OWC. This screen shot is from Disk Utility. It already has one volume inside Container disk14, called “Thunderblade 8”.

To create a second volume:

Because volumes share space with all other volumes, you can either:

Since Time Machine will store files until it runs out of space, setting a Quota prevents you from filling the drive with backup files.

My recommendation is to set the Quota to 1.5X the size of your internal drive. This provides room for all your data, plus older copies in case you need to go back in time.

Click Add to create this volume.


There are three big advantages to creating multiple APFS volumes:

  1. Speed
  2. Dynamic space allocation
  3. Only uses one computer port

The speed benefit didn’t occur to me until I was writing this tutorial. SSD speed is determined by how it connects to your computer – USB-A, USB-C or Thunderbolt – the controller chips it uses, and the number of SSD blades it contains.

For SSD RAIDs, the greatest speed is obtained by formatting all the blades into a single unit. If one SSD blade is reserved for Time Machine and the others are formatted into a RAID, my total speed drops by at least 25%.

By creating multiple volumes in the same container, I get the maximum speed for each volume. While this doesn’t make a whole lot of difference to Time Machine, the benefits to my production work are significant.

Volumes stored in the same container dynamically share space. Volumes only occupy the space required by the data they contain. They grow or shrink dynamically. Hardware-based storage is always and only the same size.

Plus, the benefits of connecting multiple volumes through one port are obvious.

This volume is not a folder. It isn’t “contained” inside the Thunderbolt volume. They are both stored on the same hardware, but act independently.


Prior to learning this, I formatted a 4-drive Thunderblade where  one blade was a stand-alone Time Machine backup and the remaining three were grouped into a RAID 0 for video editing.

Once I re-formatted the RAID to include all four drives – which required copying all files off, creating a new RAID, then copying all the files back – total system write speeds improved 35% and read speeds improved 14%. These increased speeds applied to both the main storage and Time Machine volumes.

Totally worth the effort and, now, I have a Time Machine volume with dynamic space allocation without tying up an extra computer port.

Bookmark the permalink.

2 Responses to Use APFS to Create Faster Time Machine Volumes

  1. George Bumiller says:

    Thanks for the heads-up about APFS and SSD raids.

    Since this is used for Time Machine (back-up), at least from that point of view, it would seem to have a rather long life for the SSD. And since the use as an editing storage would likely have fewer writes, that also would lengthen the SSD life.

    Any estimates on the SSD life?

    • Larry says:


      I asked the tech folks at OWC about overall SSD life and they told me they plan on a five year life for an SSD blade. That which shortens an SSD’s life is writes. Reads cause no wear and tear. So if you principally read from an SSD – media storage is an example where we write it once but access it over and over – an SSD should last longer.


Leave a Reply

Your email address will not be published. Required fields are marked *

Larry Recommends:

FCPX Complete

NEW & Updated!

Edit smarter with Larry’s latest training, all available in our store.

Access over 1,900 on-demand video editing courses. Become a member of our Video Training Library today!


Subscribe to Larry's FREE weekly newsletter and save 10%
on your first purchase.