I'm afraid that won't work. The previews folder needs to be in the same folder as your catalog. Maybe you should move everything to the external hard drive. The other solution would be to stop using 1:1 previews. They don't benefit you at all in the develop module. They are only used by the library module. Or, you could choose to delete your 1:1 previews after one week. It's not necessary to keep them forever.
I'm assuming using an alias could break things? I've tricked lots of content in Logic that way and it works flawlessly. I was surprised a web search didn't turn up any results. It would seem that the point of Smart Previews is boot drive space, so moving other previews to an external seems like a natural progression in future versions. Moving the project to the external wouldn't always work for me.
However, I had absolutely no idea the 1:1 didn't help in the Develop module. Is that accurate? All I know is when I bought version 4 I absolutely had to have 1:1 or the whole thing would crawl and the image appearing sharp in the Develop module would take forever. I noticed a significant difference (or so I thought?) and I never used the Library module until about a week ago when I started really getting organized, I just used the film strip in Develop for my navigation.
If the 1:1 truly only affects the Library preview then I can indeed delete them all and save half my boot drive!
The point of smart previews is not to save disk space. The purpose of smart previews is to enable you to do Lightroom editing while the master photos are not connected to the computer. When those master photos are again connected, any adjustments made to the smart previews will automatically apply to the master files. You might appreciate this video:
I'm well aware, thanks. I meant that by allowing you to keep your master files on an external drive, you save space on your boot drive. Externals are useful for multi-user/multi-system settings, but for individuals like me, the only reason I use externals (aside from backups) is because my internal drive doesn't have infinite space. Many of us put our master files on externals simply because if we didn't our internal drives would always be full. In the respect that they allow us to not have to have our master files, which take up a lot of space, with us all the time, smart previews do indeed save us valuable (internal) space. In the same respect, when editing with smart previews, I'd happily have my 1:1's with my master files elsewhere. But if they are irrelevant in the Develop module, I'll just delete them. Thanks.
But if they are irrelevant in the Develop module, I'll just delete them. Thanks.
But they are useful (and needed) for Library Module.
If you want to put previews on a different drive than catalog, do so, and leave a link to said previews in place Lr expects.
PreviewExporter has a feature that will do it for you, free by me:
PS - You can't separate 1:1 library previews from the rest of the library previews - sorry.