Is there anyone who is using a DT3 database on an external SD card? (Cf. Macbook Pro)

I’m contemplating upgrading to the Macbook Pro 16 and finding it difficult to decide between the 512GB SSD and the 1TB option.

If I can store the largest but least frequently accessed database on an external SD card, I can go with 512GB (since Macbook Pro 16 has a SD card slot).

However, I’m curious about the potential slowdown when starting DT3 and conducting database searches. I’m interested in hearing from anyone who has experience using a database on an external SD card and would appreciate their insights and opinions.

Get the 1TB machine. Just do it. It won’t be just DEVONthink storage that hampers you if you get the tiny disk.

My hunch is that the external SD card won’t be as reliable as the internal Apple SD disk, and for sure (IMHO) you need to plan for how you will do routine (and best to be automated) full system backkups.


I think you’d want to avoid SD cards for longer term storage and complex files systems, but you can still save good money going for the 512GB and buy an SSD external drive instead.

rmschne is right that if you can afford the larger storage option that is a much better bet in terms of future proofing your machine. On the other hand, my employer buys my MBPs for me and only ever offers base line models, so I have the 14" M1 with 512 storage. I occasionally use the very reasonably priced Crucial X8 for further storage.


It is not recommended to routinely use your DEVONthink databases on an SD card or thumb drive. It may be used as a vector for moving databases between machines. A portable external hard drive is suggested.

However, a card or thumb drive can be used to house a local sync store, if needed.


I don’t understand what you meant by housing a local sync store. Could you please explain it? For your reference, my DT3 databases are syncing on two devices via CloudKit.

One of the sync options is a local sync store. From the In & Out > Sync section of the built-in Help and manual

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I’m using an Intel iMac 2019 with 1TB SSD, and my databases are always there, too. So reliability may be a minor issue. And more importantly, I’m trying to avoid the 1TB configuration due to the high price. But I have to think about it. Thanks.

Disk space is much less critical. You can easily extend your storage, as needed. RAM, not so. Get as much RAM as is affordable.


NVMe SSDs are far, far better in performance and reliability than even the best SD cards.

  • Sequential read/write (e.g. copying a movie): 20+ times faster.
  • Random read/write (e.g. retrieving a large number of small text files scattered across your storage): 10+ times faster.
  • More robust everything, in no small part due to SSDs having a larger form factor.

Moreover, SD cards are not designed for frequent read and write operations. A database program can quickly wear them down.

As others have mentioned, If you must put your database in an external storage, portable SSDs are a solid choice. I’m using a Samsung T7 Shield to store a large collection of documents. Any portable SSD with a marketed top speed of 1000MB/s or more will serve you well.