Take the 2-minute tour ×
Ask Different is a question and answer site for power users of Apple hardware and software. It's 100% free, no registration required.

From what I understand, the implementation of the Fusion Drive is at the OS level (coreStorage). Yet, I want to know if it's possible to manually interfere in the management for a specific file or directory.

E.g. Most Photos in iPhoto are rarely used, yet I would like to push the entire directory ~/Pictures/iPhoto Library.photolibrary to the SSD.

share|improve this question
Shouldn't individual pictures get moved to SSD automatically if they are accessed often enough? –  patrix Nov 10 '12 at 19:04
@patrix Don't know. –  gentmatt Nov 12 '12 at 14:13
The directory is on a different piece of the disk to the data so could well be in cache automatically –  Mark Dec 10 '12 at 13:33

2 Answers 2

I am aware this may not be the technical answer you seek, but it's the pragmatic solution at present. Hopefully, a non-buggy way to micro manage the tiered storage will become known, but here are things you can do today, out of the box.

  • ensure all data fits on the SSD so that no tiering takes place.
  • manually access these files to ensure the algorithm sees them as being read more than the rest. Using dd to read the files would be a good start and rebuilding the iPhoto library databases should also force a full read of the contents. It's not clear reads only will affect tiering in a "mandatory promotion to SSD storage" sense.
share|improve this answer
If you want to add these as non-starter, things you have tried steps to your question, you have my full encouragement. –  bmike Nov 10 '12 at 17:59
Using a script to run at login to read the directory sounds like a good idea. –  gentmatt Nov 12 '12 at 14:16

Try the following script

echo $1

dd if="$1" of=/dev/zero bs=1m
share|improve this answer

We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

What does this do? –  Mark Oct 18 '13 at 10:19

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.