Apple doesn't "recommend" storing photos on a network drive (eg a NAS) but why? What are the technical issues? I have a Synology NAS where I can create a sparsebundle dmg disk image as a repository for my photos libraries. What are the risks?
If you look into the Photos Library bundle you will see that many of the database files inside are SQLite databases. SQLite is not synchronised for network transactions. A Photos Library needs to be stored locally on the computer where Photos running, or you are risking inconstancies in the internal databases. Network databases are expensive (for example FileMaker Pro), because all database transactions need to be synchronised for network access. Photos has been designed as a single user, local database and is only safe to use, if the Photos Library is on a locally mounted volume.
If you look into the Photos Library bundle you will see that many of the database files inside are SQLite databases. SQLite is not synchronised for network transactions. A Photos Library needs to be stored locally on the computer where Photos running, or you are risking inconstancies in the internal databases. Network databases are expensive (for example FileMaker Pro), because all database transactions need to be synchronised for network access. Photos has been designed as a single user, local database and is only safe to use, if the Photos Library is on a locally mounted volume.
The system that runs a NAS and the format of the drives are not compatible with the complex ecosystem of file permissions and hard links that make up a Photo library. Many users have used a NAS for a while but eventually find their library damaged and corrupted and unable to be fixed.
I am not sure - I would not risk it. The problem is, that the Photos.app is launching many background processes, that might try to access the library and there may be race conditions.If you risk keeping the library on a NAS, keep a backup copy on a locally mounted volume.
Thanks for the prompt response. The only formal Apple comment is that network drives are not “recommended”. “Not recommended” isn’t the same as “do not use” [a NAS]. It makes you wonder if Apple are trying to promote big drives on their laptops! I wonder if Synology has a point of view?
Ah ha a comprehensive and understandable explanation. One further thought. My use of a NAS photo library would be to / from ONE DEVICE at a time ie no file locking requirements to avoid “deadly embraces”! Does that make a difference?
Many thanks
NAS Storage of Photos Libraries?
