How would LR4 use a SSD and a larger sized HDD in this scenario?

I'm thinking of getting a 160GB SSD to store Windows and all other programs. I would then use a second drive bay for a larger 700GB HDD to store my large RAW files. From what I understand, this is typically supposed to speed things up during editing with LR4.

However, since I'm using DNG files and not CR2 with the sidecar XMP files, wouldn't LR4 still be constantly reading/writing to the HDD every time I edit my images?

No because the "edit" are not actually edits since LR is non-destructive. The "edits" are saved in the LR catalog file and the images are never touched. By default the catalog file is created on the drive LR was installed in. So the RAW files would be just read from the HDD while the application and catalog are read and run from the SSD. This is how I have mine setup.

I imagine you should be able to set up the catalog location though, you'd just have to look through the settings.

Oh yea, you can def move the catalog anywhere, but IMO on the SSD is the best place to have it.

Catalog on SSD will give you more benefit than OS. Starting your OS and programs quickly's nice to have, but cache and catalog on SSD makes your work faster.

Ok, that all makes sense thus far. However, there is an option somewhere in the settings that says aomething along the lines of "write/save changes immediately" vs saving on exit only...this is actually what made me think that with this option enabled, LR might actually be accessing the DNG files on the HDD, rather than the catalog or XMP files (which obviously aren't existent for DNG)

How do you guys do this? Put the current batch of files on the SSD, do your editing work, then move them all over to the 1-2TB or larger storage and make room for the newest batch on the SSD?

mikeinctown wrote in post #14655615
How do you guys do this? Put the current batch of files on the SSD, do your editing work, then move them all over to the 1-2TB or larger storage and make room for the newest batch on the SSD?

That was going to be my next question...

I was thinking there must be an option somewhere in LR4 that allows you to choose where you save the catalog files. So I would assume you save the images on the standard HDD, open them with LR4, and have it set up to create the catalog files on the SSD. I'm just not sure how this is going to work with DNG, since I thought part of the reason people used DNG was so that they could eliminate the XMP files and have the edit settings written directly into the RAW/DNG file, while still retaining the oiginal version in the same file...but doing this would then require access to the stored file on the standard HDD. So I don't see how this process would take advantage of having a SSD.

I can't actually confirm this since my 6yr old primary computer has been inoperable for about a week now. Going to be nice to switch from a Core 2 Duo to a Core i7 and SSD + HDD setup for these edits...if I can get things configured correctly.

Here is what I have.

260Gb SSD. I have my applications and the catalog file on this drive. I also have 25Gb of space allocated for the catalog file cache (how much space Lightroom keeps for Preview files)

I have a 2Tb drive that stores all the Raw files. Also internal.

Edit: Reread your post, and I think that you think the DNG files are stored in the Lightroom catalog. If you think this, this is not correct. The catalog is a database that, depending on your catalog cache size it references a certain number of previews. But even the previews are not kept in the same file. The DNGs are not stored in the catalog file.

Let me try to rephrase my question, but in the form of a hypothetical situation...

Let's say I have DNGs saved to the HDD, catalog on the SSD. My SSD fails and I am left with only the DNG files in the HDD. When I transfer my DNG file to another computer with lightroom, are my most recent settings (edits) going to be available?

I was under the impression that the answer should be "yes". And if yes, then obviously Lightroom was accessing the HDD during editing, thus making me question how effective a SSD is when using DNG files. If the answer is no, then I guess I'm not quite sure how exactly DNG files are being used in the editing process.

mannetti21 wrote in post #14656565
Let's say I have DNGs saved to the HDD, catalog on the SSD. My SSD fails and I am left with only the DNG files in the HDD. When I transfer my DNG file to another computer with lightroom, are my most recent settings (edits) going to be available?

Depends on this setting in the prefs:

Ok, so in that screen shot, assuming I'm editing a DNG file...if I check automatically write to XMP, then I basically negate the benefits of using a SSD, since it would be accessing the HDD to actually write to the DNG, since there is no XMP.

Now if I DON'T check that box, then how would I be able to apply/save the settings to the DNG file?

Lightroom is able to write the changes to a sidecar file (XMP) which it does during times of low load, or demand.
Lightroom itself does not refer to these XMP files.

Lightroom works from its Catalog, which is really a Database with all the information about every image you import, including the location of that image.
When you work on a photo Lightroom accesses both the Catalog file AND the original file AND any preview files it may have generated for that image (the location of which are also stored in the database catalog).

The Catalog and Previews have to be stored together on the same drive, that also needs to be a local drive. But you can store images pretty much where every you like, including on a network drive.

Putting the Catalog and Previews on a separate drive to the images shows a noticeable increase in performance.
If that drive is an SSD, then in theory, and from what people are saying, the performance is even better.

Using XMP or DNG should have no impact on performance, as the updates are done only when the drive and LR are not busy, and they are small and make very little demand of system resources.

You get some benefit from raw files on an SSD, but not a huge amount. Putting raw files and catalog on the same SSD you're asking that drive to do a lot of work, which is why I have two SSDs, to split the load across physical devices.

tim wrote in post #14654015
Catalog on SSD will give you more benefit than OS. Starting your OS and programs quickly's nice to have, but cache and catalog on SSD makes your work faster.

Ah-ha! This is where I have not used my new SSD to its fullest capability. Looks like I shall be moving my catalogs over to the SSD tomorrow. Thanks, Tim!