How to move your Mac’s Photos library to an SSD for better performance

Photos for the Mac is a storage hog. It likes to read and write from its storage with abandon, no matter how much memory you have. Because a Photos library can become quite large—mine apparently pushes 500GB—you may have resorted as I did by storing your library on an external drive.

Or, if you have a high-capacity startup volume that holds your Photos library, that storage may be a Fusion drive, Apple’s now-retired technique of pairing a slow hard drive with a low-capacity, super-fast SSD.

You might be ready for the switch to SSD, which you can now do without breaking the bank.

Pick an affordable SSD for mid-range performance

If you’re like me, you reached a point of frustration with hard disk speeds with a large Photos library. Despite the exceptional performance of my M1 Mac mini and the external Thunderbolt 3-connected SSD startup drive I use, Photos can take tens of seconds to several minutes to accomplish certain tasks because of the excessive drive access required.

You might also be in the same boat that you can’t afford or justify the cost of a 2TB or higher storage capacity SSD with the kind of performance you want in a single startup volume. (Consult my article “How to start up your M1 Mac from an external drive” for details on switching to an external drive with an M1-series Mac with a 1TB SSD, and my more general advice in “An External SSD Gave My iMac a New Lease on Life.”)

There’s good news, however. The continued growth of SSD usage means prices keep falling on lower-capacity drives. You can purchase a well-reviewed Samsung T5 compact mid-range SSD with 1TB capacity for $120. This can let you have the best of multiple worlds. It’s delightfully tiny—about as thick as a Pop-Tart and a footprint that’s half that treat’s area.

This drive and others in its class use a SATA interface, which maxes out at about 600 MB/s (4.8 Gbps) over a USB 3.1 connection, but in practice performs slightly worse. The Samsung above tests out at about 425 MB/s (3.4 Gbps) for reading and writing—which is 10 times faster than the hard drive storage you were using to hold your Photos library.

More expensive NMVe/PCIe-based SSDs can work several times faster. My startup drive uses a Thunderbolt 3 enclosure and an NMVe SSD, which in active use as the startup volume performs at about 1,000 MB/s (1 GB/s) in writing tests and 2,000 MB/s (2 GB/s) for reading. The cost can be two to three times as much for the same capacity as a SATA drive, however.

(To get tweaky, USB 3.1 Gen 2 has a top rate of 10 Gbps or 1,250 MB/s, so you don’t need Thunderbolt 3 or 4 with a SATA drive. For an NVMe SSD that can deliver gigabytes per second, Thunderbolt 3 or 4 is a must with up to 40 Gbps or 5 GB/s throughput.)

Migrate your Photos library to SSD

If you think this move is for you, here’s how to make the transition:

1. After acquiring the drive, figure out the interface you want to use. The Samsung T5 has a USB-C (USB 3.1 Gen 2) port and comes with cables for USB-C and Type-A. It can perform at maximum speed over a Type-A connection, so you may not want to tie up a USB-C port with it.
2. Attach the drive and launch Disk Utility. The drive almost certainly isn’t formatted for a Mac. Reformat with APFS and GUID Partition Map. (See “Can’t find the Scheme menu in macOS’s Disk Utility? Here’s how to find it” for how to find the drive’s formatting and set it to the correct filesystem.)
3. Quit Photos and copy the Photos library to the drive. See “How to copy your Photos library from one Mac to another.”
4. Hold down the Option key and launch Photos. A dialog appears showing the current library selection. Click the Other button to select the library on the new drive.
5. Go to Photos > Preferences > General and click Use as System Library. This prompts a warning about partially uploaded files and other issues that’s not relevant unless you had some operation in progress earlier. Confirm.
6. You may need to wait for some time. Photos took about three hours with my library before it became responsive again, as it had to examine the previous library to make the full system transition. Be patient.
7. If you use iCloud Photos, you can now re-enable it. Go to Photos > Preferences > iCloud, check the iCloud Photos box, and select Download Originals to This Mac. Photos may then perform a lengthy re-sync that won’t change any files, but it didn’t do so in my testing.

Once everything has processed, you’ll be left with zippier access to stored photos and vastly faster editing controls.

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