Are three copies necessary?
I stopped using "Attach Link to File" and I'm now using "Attach Stored Copy of File". I also moved my data directory off OneDrive and onto a local folder because that is what the Zotero documentation recommends. And I'm using pCloud to sync files (instead of pointing multiple machines to the OneDrive data directory). I'm continuing to use my Zotero account for data sync (no change), though I notice that Zotero still creates .sqlite files in my date directory (why? Isn't data being synced to my Zotero account since that is what I have configured?)
I've taken these actions to hopefully avoid recurring problems with disappearing link targets. Everything seems to be working fine, but it occurs to me that now there are a minimum of 3 copies of each pdf -- the original, the one that gets created in the local Zotero data directory, and the one that syncs to pCloud, plus additional copies when I sync other machines.
Is this as expected, or am I doing too much here?
I've taken these actions to hopefully avoid recurring problems with disappearing link targets. Everything seems to be working fine, but it occurs to me that now there are a minimum of 3 copies of each pdf -- the original, the one that gets created in the local Zotero data directory, and the one that syncs to pCloud, plus additional copies when I sync other machines.
Is this as expected, or am I doing too much here?
You can use "as needed" file sync mode on other computers if you want to avoid downloading all files preemptively. A future version of Zotero will offer more advanced management of how much local disk space is used to store files that exist on the server.
https://www.zotero.org/support/sync#alternative_syncing_solutions
My understanding is that the local data directory always includes both the database and the files. I understand that they can both be synced to different cloud locations, but on the local machine, I have not seen a way to separate them. Is there a way to separate them?
Again, that page explains your options. If there was some other option I would've told you. If you're not comfortable using symlinks or selective sync, then I guess those options wouldn't apply to you and your only option would be to use linked files instead of stored files, as is also explained there.