robert_ardill's profile

45 Messages

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1.2K Points

Thu, Nov 24, 2011 9:04 AM

Lightroom: Allow Catalog and Previews to be on different drives. Performance and Flexibility.

Lightroom: I would like to be able to have the previews on a different drive to the catalog ... or simply be able to use a link or junction (currently Lightroom prevents this for a reason that I don't understand ... perhaps to do with not allowing network drives?). This would mean that the catalog could be on an SSD, for example, and the previews on a hard drive.

This conversation has been merged. Please refer the main conversation:

Lightroom: Lighroom Preview.lrdata, allow it to be put in different location of catalog

Responses

Champion

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6K Messages

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103.7K Points

10 y ago

On Windows, you can put the catalog on one drive and the previews on another using symbolic links (“mklink”). What led you to believe you couldn’t do it?

However, it’s likely you’ll see little improvement by putting the catalog and previews on separate drives. The reason is that physical disk i/o to the previews is 5 to 20 times higher (throughput and transfers per sec) than to the catalog. The catalog is relatively small and ends up getting largely cached in memory by the OS and by LR, especially if you have a reasonable amount of memory installed on your machine (e.g. 6 GB or more).

See these for discussions of using multiple drives and the modest benefits of using SSD drives:

http://forums.adobe.com/thread/778350...
http://forums.adobe.com/message/38307...
http://www.computer-darkroom.com/blog...

45 Messages

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1.2K Points

10 y ago

Thanks John - I think I was thinking back to trying to trying to have the LR Catalog on a memory disk in XP and this didn't work. I'm not going to try this again on Win 7 as my experience with memory disks was very discouraging on XP (very unstable) and really the performance on the LR catalog is fine on the machine I now have. I could separate the catalog and previews using a junction or symbolic link, but as I have both on mirrored disks I will leave them there for data redundancy.

BTW - on my system the RAID 1 is giving me about twice the read rate of a single disk so that reading is very fast (also using fast disks which helps) and writing is about the same as with a single disk ... so for anyone looking for both performance and some level of protection against disk failure, I can recommend RAID 1 on fast disks rather than going the SSD route. Also Diskeeper helps a lot (both for hard disks and SSDs).