Best external drive to back up 2024 iMac

pvillage wrote:

What is the best compatible external drive to back up 2024 iMac (M3)?

Best? That would probably be multiple NAS storage arrays with sufficient RAID-6 or RAID-10 storage capacity for current and likely future usage.

As for a “cheap”* direct-attached solution, whatever available preferably non-shingled / not-SMR HDD is available with, say, three or more times the intended protected capacity, if your chosen backup means is Time Machine. Preferably two of these HDDs, to allow some diversity and rotation.

I would not choose SSD here due to increased price and/or smaller capacity for SSD, and the added performance is probably not required here. Not unless you’re restoring full backups quite often, or have smaller backup windows. HDD gets bigger storage for the same costs. And desktops can back up…whenever.

One resource for learning about storage and NAS: https://nascompares.com/ (as well as their YouTube)

*this being 2026, nothing is.

For me the question hinges on the level of reliability you feel you require. For maximum backup reliability with our desktop computer, I only use self-powered external drive enclosures holding quality 3.5-inch mechanical drives.

"Self-powered" means the drive has an independent power supply. Low-cost "mobile" or "portable" drives that are bus-powered must get all their power from the computer's USB ports. A prime cause of reliabilty issues with bus powered drive is they can demand more power than one port can supply.

I have two of these self-powered enclosures backing up my income-producing iMac:

https://eshop.macsales.com/shop/owc-mercury-elite-pro

One is for Time Machine backups, and the other for Carbon Copy Cloner backups. I bought them as bare enclosures and installed 3..5-inch WD "Black" series mech drives, rated SATA-6GB and 7200 rpm. Install took less than 5 minutes and one screwdriver.

The mech drives are only slow for Time Machine's first backup; once Time Machine completes the initial write, all subsequent incremental backups are fast and not at all intrusive to my workflow. The Carbon Copy Clone drive is scheduled to do its thing at 4AM every day. I'm seldom up that early!

We have multiple Macs backed up to OWC self-powered enclosures, and the oldest enclosure is over 15 years old. None has ever given us any grief.

In the end, whether you go with a high- or low-end backup capability in an external drive distills to one simple question:

Is the loss of my files an inconvenience or a tragedy?

Any SSD at least twice the size of your iMac's internal drive formatted as APFS will work with Time Machine.

If you get an HDD be sure to get a self powered one. They draw a lot of energy and can overwhelm a port energy wise.

Also get a drive that's 2 to 3 times the size of the drive you want to back up.

If you have a lot of files that don't get changed at all or not very often you can squeeze in more backups on a drive due to the fact those files are represented by hard links which only take up 27 bytes regardless of the size of the file it's representing.

I have a 4 TB drive backing up 3.1 TB of data and I have 52 backups going back to last Dec. There's still 664 GB left free.

If you want to have the backups go back further then get a larger drive. For me 6 months is more than adequate.

dialabrain wrote:

FWIW, in 20+ years I've never had a use for an NAS storage array. 🤷‍♂️

The Apple NAS option for many years was Apple AirPort Time Capsule. Various models were sold.

Time Capsule was particularly handy for Mac laptop backups. This because Time Machine backups happened without needing a cable. Whenever the laptop was in range of the Wi-Fi, the backups happened. The folks with the laptops were forgetful about cables.

Wired backups to NAS are also available and work quite well, and have advantages over local direct-wired storage.

TIme Capsule was also handy for smaller configurations with pooled backup storage for multiple Macs.

In more recent times, NAS remains handy those same use cases, and with larger storage options also now available, and optionally for other local networking services where required. Media services, local file shares, remote offsite backups, etc.

One other more subtler advantage of NAS is keeping the backups in the background. Prior to using Time Capsule NAS, the external backup storage was too often getting not-connected or was getting randomly disconnected by the gremlins and “for reasons”. Sometimes with backups actively running. With NAS, the gremlins had (have) to go find the backup storage else-network, and unplug it. Which happens less often. Out of sight, out of mind, automatically.

FWIW, in 20+ years I've never had a use for an NAS storage array. 🤷‍♂️

I use my nas to put home video and stuff on and the synology app and or vlc app on my appletv can access it without my computer have to be online

As for a "cheap solution", I still use the old vintage mechanical HDD drive for my Time Machine Back-ups!

I don´t really think I need a NAS for this!

"But each to their own taste"