The catalogue as I understand it is just the database for LR's internal purposes rather than for the direct purpose of the user? Image files however are structured in FOLDERS, thus to work on a file in LR you open up its FOLDER, not the whole blooming catalogue.
Not quite sure that's right.
The catalogue stores:
- A reference to where the photo is on your system
- Instructions for how you want to process the photo
- Metadata, such as ratings and keywords that you apply to photos to help you find or organize them
As such you will indeed require to open the catalogue. When you import photos into Lightroom, you create a link between the photo itself and the record of the photo in the catalogue. Then, any work you perform on the photo — such as adding keywords or removing red eye — is stored in the photo's record in the catalogue as additional metadata.
Within Lightroom I import with keywords, to help with metadata searches. Lightroom imports into a folder of the date the image was created, so I have yearly folders (2012, 2013, 2014 etc) with the date subfolders with the raw (unprocessed) images in underneath.
Within Lightroom I use Collections. These have Main Collection sets of Car, Sport, Family, OCA etc, then sub collection sets of year and the sub collections itemised by event. i.e. Car, 2014, Castle Coombe, TVR photoshoot etc.
Usually I find images by drilling through the collection sets, but can also search by metadata, keywords,, date etc.
For the physical disks I have 3 x 600Gb WD Raptor drives (operating system, Lightroom cache and catalogue, and this years raw) & 2 x 3Tb Sata drives for splitting the other years raw files onto.
I then have another 2Tb drive for exported Jpegs and other data.
All this is backed up to a 12Tb Nas system weekly, and two other 3Tb removable USB drives taken offsite monthly.
With a pair of 6 core Xeon processors and 20Gb of Ram and my disk setup, I don't find I have any performance issues running my 120K catalogue.