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

I just had a long discussion about this topic with an Adobe rep...

I told him I would be importing CR2 RAW files and converting them to DNG files, and activating the option to "Automatically write changes to XMP". I told him I would have dual storage drives installed; a 160GB SSD (for Windows/programs and catalog file) and a 750GB HDD (for all other storage including DNG image files). My question was; is this the proper setup to take advantage of the speed of a SSD and optimize Lightroom performance?

The answer was No. I was told that if using DNG files, I would need to do one of the following for best performance: Save the DNG image files to the SSD -or- "Uncheck Automatically write changes to XMP" and keep the DNG files on the HDD.

He went on further to explain that the Auto Write option would result in writing to the DNG files every time a slider was moved, and NOT simply when LR wasn't busy or when exiting LR (I specifically asked about those 2 questions). Therefore, the HDD would be constantly accessed to write data IN ADDITION to accessing the SSD to write to the catalog.

Saving all DNG files and catalog file to the SSD would maximize performance, but at the obvious cost of limited storage space. Rep also stated, "constant and repeated reading/writing to SSD may cause premature failure".

Therefore,

The solution he provided was to disable "Auto write changes to XMP", save DNGs to the HDD, catalog and previews to the SSD, and manually "Save Metadata to File" whenever I want to save my progress or final edit into the RAW file. After doing so, the DNG file would be able to be transferred to any other program or computer, and still retain an edited version rather than starting from scratch.


So, I wasn't sure about the "Write changes to XMP" option specifically when working with DNG files, but his explanation makes perfect sense. If using a SSD and HDD, with DNG file formats and no .XMP sidecar files, we need to simply disable the option.

Interesting that it saves the whole DNG whenever a slider's moved with that option turned on. To be honest I wouldn't believe what they said until I tested it for myself.

If it's true leaving as CR2 would be more efficient, so it only saves XMP files which are tiny.

tim wrote in post #14661889
Interesting that it saves the whole DNG whenever a slider's moved with that option turned on. To be honest I wouldn't believe what they said until I tested it for myself.

If it's true leaving as CR2 would be more efficient, so it only saves XMP files which are tiny.

This may be a matter of semantics, but I don't think it saves the entire DNG each time a slider is adjusted. I think it simply saves to its embedded version of its XMP...not sure if that necessarily means re-writing the entire 20-30MB file. I can't imagine my current hardward being able to even ATTEMPT to keep up with hundreds of 20-30MB saves during editing.

I can say from my experience using LR4 on an old Core 2 Duo T7300 2.0GHz, Vista 32bit, 2GB RAM, that when the Auto Write option is enabled, things tend to slow down and frequently freeze up. After un-checking that option a few weeks ago, performance has definitely improved somewhat and I've had NO lock-ups.

CR2 with XMPs seems the absolute most efficient choice, regardless of the number or types of storage drives, but I just dislike having two files for each image, AND having to make sure they stay together when I move things around or back-up to an external HDD. One of my fears is spending hours editing, then somehow losing an XMP file, and having to start from scratch again.

So I guess that leaves me to saving to DNG only sporadically, maybe every few days...which I suppose is no more risky than saving to only XMPs while the RAW file is located somewhere else.

mannetti21 wrote in post #14661391
I just had a long discussion about this topic with an Adobe rep...

You either misunderstood him, or he is mis-informed (like many reps).

mannetti21 wrote in post #14662026
This may be a matter of semantics, but I don't think it saves the entire DNG each time a slider is adjusted. I think it simply saves to its embedded version of its XMP...not sure if that necessarily means re-writing the entire 20-30MB file.

Yes, the DNG update does rewrite the whole file, it simply updates the changes.
LR is very good at multitasking and gives different priority to different things.
Writing XMP's or updating DNG's is given quite low priority. Catalog changes, preview updates and image renders are all given higher priority.


Current generation SSD's will last years, even if used heavily as they would be with a LR catalog stored on them.
It was only the very early models that had any potential for problems.

mannetti21 wrote in post #14661391
I
I can't imagine my current hardward being able to even ATTEMPT to keep up with hundreds of 20-30MB saves during editing.

I can say from my experience using LR4 on an old Core 2 Duo T7300 2.0GHz, Vista 32bit, 2GB RAM, that when the Auto Write option is enabled, things tend to slow down and frequently freeze up. After un-checking that option a few weeks ago, performance has definitely improved somewhat and I've had NO lock-ups.

With that level of spec, it would slow down trying to open a note pad file while you have LR open.
It is well below what I could consider minimum spec for running LR4.
With a single HDD and write to XMP enabled then your asking LR to access its Catalog and the XMP file at the same time on the same drive and a Hard Drive can only do one thing at a time.

mannetti21 wrote in post #14661391
I
CR2 with XMPs seems the absolute most efficient choice, regardless of the number or types of storage drives, but I just dislike having two files for each image, AND having to make sure they stay together when I move things around or back-up to an external HDD. One of my fears is spending hours editing, then somehow losing an XMP file, and having to start from scratch again.

So I guess that leaves me to saving to DNG only sporadically, maybe every few days...which I suppose is no more risky than saving to only XMPs while the RAW file is located somewhere else.

Remember LR works from its Catalog, it does not read the XMP file, or the DNG.
If you put your Catalog file on a separate drive to your image files then there will never be a conflict in attempting to access them.
That is the best way to improve its performance as a decent computer not CPU or RAM limited (i.e. i5 or i7 Quad Core with 8GB or more of RAM) can easily access data from multiple drives at the same time.


If you move files with XMP's using LR it will move the XMP with it, and you don't have to resync or update file locations in the catalog.

And since the XMP files are written next to the RAW file, backing up should never be a problem as you should be backing up entire folders or drives.

Lots of additional info there, much of which adds to my confusion...

You mention that LR is good at multitasking, and that writing/updating DNG/XMP is given low priority. Fair enough, but wouldn't constantly having to re-write a 30MB DNG, rather than a 10kb XMP, have some sort of negative effect on efficiency? I realize my current specs are 6yrs outdated, but even with a new i7 on the way, there has to be an increased demand on the processor and storage drives...even if someone is using a setup powerful enough to mask those increased demands during normal usage.

I'm going to be brave and say that the obvious answer is yes. Therefore, I would think that the Adobe rep's suggestion of disabling the Auto Write option would be appropriate, regardless of single/dual HDD or SSD's.

mannetti21 wrote in post #14662328
Lots of additional info there, much of which adds to my confusion...

You mention that LR is good at multitasking, and that writing/updating DNG/XMP is given low priority. Fair enough, but wouldn't constantly having to re-write a 30MB DNG, rather than a 10kb XMP, have some sort of negative effect on efficiency?

It doesn't rewrite the whole 30MB file, it just updates the 10kb that has changed in the file.

Ok, well that makes sense as I'd expect my current laptop to be utterly incapable of constantly saving 30MB files while performing other editing operations.

I'm almost tempted to call Adobe again, ask the same question, and see what answer I get this time. The guy should have just told me to disable Auto Write if I have a single HDD. For dual drives, simply separate catalog and DNGs and not worry about anything else in terms of influencing performance.