Choosing Your Catalog System
Before we visit Lightroom's all-important catalog settings, let's look at two ways you can work with catalogs. You can adopt one or the other based on your workflow demands.
A Single Catalog System
As a simple solution, the program can manage all your image files in one catalog based on their existing location. If you like organizing your files by month in a folder, and putting all the months on one drive or on any number of external hard drives, you can maintain this type of structure by just pointing Lightroom to where the files are and importing them, and they will be linked to the catalog. On the other hand, Lightroom can be instructed to copy all images to a defined location and build the database around this single location. This provides plenty of flexibility in managing and searching image files from a single catalog.
One disadvantage when you create a large single catalog is that you can run into the danger of filling up your computer hard drive with original images, preview images, and metadata XMP files that might rarely be accessed over a long periods of time. Large catalogs with 10,000 to 20,000 images can slow down your computer, depending on your machine's processor speed and internal RAM. These files can sit on your computer, taking up valuable hard drive space. Using the large, single catalog system you can outgrow your hard drive space in a short period of time if you are a high-volume photographer. Laptop users beware; it may be best to develop an external hard drive storage approach to your workflow. Most laptops do not have large internal storage capacity.
And be aware that the crack teams of Adobe Lightroom programmers are looking out for your assets. They have incorporated features in Lightroom to manage the storage problem by re-referencing the images when they are moved to other external storage drives. Using Lightroom's ability to export and merge catalogs can also provide a way to manage most workflows when they outgrow the storage space. In most cases, your pile of images will simply grow and grow and at some point will outgrow your storage capacity. There are many storage options available, but in a word, I'm thinking BluRay disk storage could be another bridge to storage issues. We are creating huge amounts of data to store in the digital age. Images, video clips, and other data will all require more storage as we keep collecting media.
Multiple Catalog Workflow (MCW)
A second possible scheme is to break up your workflow into multiple catalogs that can be merged at a later date. This system can work for wedding photographers, for example, who don't need to place all the images from every wedding in the same large catalog. Instead, each catalog could be organized under a separate client name. For example, 3,000 images from the Suzy Smith and Jimmy Jones wedding can have its own catalog. You might only visit this Smith and Jones catalog when prints are ordered and then store it away in an archive only to be accessed a few times down the road for some portfolio shots.
As I've mentioned, I call this separate catalog system the Multiple Catalog Workflow, or MCW for short. In this flexible MCW, I usually download images to my laptop and then copy files to an external hard drive and burn the images to a DVD as a backup. Having had the experience of filling up hard drive after hard drive, I have come to use a system that creates a new catalog for each event, location, and/or client.
Also remember that Lightroom can merge multiple catalogs into one catalog if and when you think all or most of the images can be contained in separate storage drives. And yes, I have two of everything for backup! (And so should you.)
If you were to adopt an MCW system for file handling where you only access the separate client catalog occasionally, you wouldn't need to create a large catalog for all your photography. I don't claim that the MCW is necessarily the best approach, but having worked with many types of photographers, I do feel it is fundamentally straightforward and easy and can help you manage your images very well. And it's easy to do: Click File > Create New Catalog.