Lightroom raw preview image questions

Hello there!

I'm starting to run low on space on my 80GB SSD and considering adding another one for raid0 but that comes with some questions regarding the raw library preview images. My preview folder is nearly 40GB and I love the speed it gives me when flipping through images.

1) If I just save the catalog file how do I manually set my computer to render new 1:1 previews for my entire library?

2) When I delete images in Lightroom, are the preview images also automatically deleted? (Currently I have it set to never purge 1:1 files)

3) What is the difference between camera raw cache and 1:1 preview cache? What kind of information is camera raw cache? AFAIK the camera raw cache doesn't impact on rendering speed when I'm using 1:1 previews. I'm assuming I'm just looking at the 1:1 previews when quickly flipping through images.

1) Select all, Library > previews > render 1:1 previews.
Not sure why you'd want to render new previews though? If you use the same catalog and images, they haven't changed.
2) No idea really. Give it a try and check the "Catalog Previews.lrdata" filesize before and after?
3) Camera Raw cache = ACR, not LR I'd guess.
When you are "flipping through" images, the 1:1 preview is used, but only as long as you didn't edit the image after creating the preview.

René Damkot wrote in post #11299681
1) Select all, Library > previews > render 1:1 previews.
Not sure why you'd want to render new previews though? If you use the same catalog and images, they haven't changed.
3) Camera Raw cache = ACR, not LR I'd guess.
When you are "flipping through" images, the 1:1 preview is used, but only as long as you didn't edit the image after creating the preview.

Thanks, I was just thinking generally if I don't save the preview folder before wiping the drive or in case the drive would get corrupted and I lost the preview folder. Great to know how easy it easy to render them again! I'm not backing up the preview folder anyway, just the catalog and images.

Lightroom does share the Camera Raw cache for Develop/1:1 previews, but for the "normal" previews it uses your Catalog folder. So, you will see that show up -- I have my 1:1 previews deleted after 30 days so that way my CR cache stays within certain limits -- after 30 days I'm pretty well done with my short term work and the images are moved to an external library drive.

Both my catalog folder and my Camera Raw chache stay on an internal data drive, although some people move a lot of things on one of the plug-in devices -- I've just never messed with them.