LR CC (newiMac) and images on MacPro internal drives - previews

[JeanMichel]

I now have a new 27" iMac, with a 3 TB Fusion drive, 16 gb ram, and the newest LR CC. My images are on 3 internal drives inside a MacPro. There is no problem withLR CC being the images (a new catalog was created on the iMac. The problem I have is that in either grid or loupe views the previews load very slowly. At first, in grid view, I got a lot of blank frames that fillip at different speeds. The full size previews can take a lot of time to load. I tried to generate 1:1 previews of a folder with some 13.000 images and after 24 hour I think that only 700 images were rendered,-- obviously not an option. The MacPro is connected to the iMac via an ethernet cable and switch box; could that be the source of the problem? My images are also on two external drives that I could attach with a USB cable, would that solution? So far, google 'help' has not addressed my issue.

Jean-Michel

[KarlGohl]

One of several things you need to consider: Are the Macs connected with gigabit ethernet?  That is, are the cables the right category and does the switch support gigabit speeds.  With gigabit ethernet, you should be able to access the files on the MP at close to full hard drive speed.  If the connection is only the slower "fast" ethernet speed (100Mb/s), then that might account for some of the slowness.  Use Finder to copy a large file from the MP to the iMac and time it to confirm what speed your connection is giving.

[KarlGohl]

A few more random observations / thoughts:
- My 5K retina i7 iMac takes about a minute to generate 1:1 previews of 12 NEX7 raw files (about 25MB per file; 24MP per image).  Raws are stored on an external hard drive attached via USB3.  Catalog (and therefore previews) stored on iMac's internal 1TB flash drive.  So I would get ~700 1:1 previews generated per hour.  If you do a similar test case (that is, generate 1:1 previews for ~10 images), what "seconds per 1:1 preview" value do you get?
- Beware: when testing preview generation speed, I delete 1:1 previews for a few images and then re-generate them.  However, LR won't actually delete previews if they are close to the same size as "standard previews" (as defined in Catalog Settings).  Since the iMac screen is about 5120 pixels wide, the Auto setting for standard previews makes them 5120 pixels wide.  Therefore, LR often won't actually delete 1:1 previews for my NEX7 images, since their 6000 pixel width is close to the width for standard previews.  To be able to really delete 1:1 previews, I have to temporarily set the standard preview size to a much smaller value.
- On further thinking, it doesn't seem that gigabit versus "fast" ethernet can account for all of your slowness: even if you are only getting 100Mb/s (which is about 10MB/s), it should only take 3 or 4 seconds to read a raw file.
- Why did you start a new catalog?  When I recently moved from a Mac Pro to new iMac, I copied the catalog and previews to the new machine.  The grid view thumbnails display quickly.  The first time I look at an image in Loupe view, I usually get the "Loading..." overlay for two or three seconds.  I assume this is because the old standard preview (sized for my old 2560 pixel wide monitor) is displayed while a new 5120 wide standard preview is generated.
- Are you sure neither machine went to sleep while you were trying to generate the large batch of previews?

[JeanMichel]

Thanks for your replies. The ethernet connection is indeed 1gb. The new catalog was created automatically when I installed LR CC, with the option of making an 'upgraded catalog'. The old catalog is an LR4 catalog. Once I generate standard previews, all goes very nicely, but it is taking quite  bit of tie; it appears that doing smaller batches works better, generating standard previews for the entire catalog did not work, although it may well be a case of the iMac going to sleep when the screen went to sleep, as you mentioned. Thanks again for your advice.
Jean-Michel

[JeanMichel]

Hi again,
I am not sure what the reason is, but after rebuilding some, not all by any means, standard previews, my LR CC and ended LR4 on the iMac show all the images in the entire catalo almost instantaneously. I wonder if it's a mater of the OS moving that info onto the ssd portion of the fusion drive.