If you have not done so already, create one (1) parent folder for all of your image folders, so that all of your image folders are sub-folders of this one parent folder. Give it a descriptive name.
This you have to do in Lr so that Lr "knows' what has been happening.
Now. close Lr and in your OS (Mac Finder / Win Explorer) move this just created parent folder (with all its sub-folders) to the new drive.
WARNING: At this point do NOT change the folder structure or the folder names.
Open Lr. You will see that all the folders in the folders panel show question marks besides them because Lr has lost the contact to these folders.
Right-click the parent folder that you created earlier and select <Update folder location> or <Find missing folder., navigate to the actual location of this folder on the new drive and click on it.
Lr will then find all the sub-folders on its own, provided you have not changed folder names or folder structure.
The LR catalog contains records which point to each image file. Apart from that the record has all metadata about the image, be that what you find within Library module-metadata panel, keywords, or all develop instructions including history and a pointer to the previews-folder.
If you move images in the way described above just the pointers to the image get updated. So no trigger to loose any other part of the record.
That is the reason why re-importing any images is such a bad idea: re-importing creates new records in the catalog (if they are not rejected as redundant) without any link to the previous records.
The path to loose your previous work would be to move the images outside of LR, accept the missing images inside your catalog so they are removed, and reimport.
As long as you follow the instructions, which just update the pointers to the image files, you should be safe.
Of course, catalog corruption can always occur, independant from any move.
So whenever you plan to do such a reorganisation it is always wise to backup your catalog first. In case you screwed up or something else went wrong you always have a defined point to restart from.
Lost previews: usually occurrs only if you rename you catalog, but forget to rename the corresponding previews-folder. This is no catastrophe, just work for your comp to recompile them (which may take some 20hours for 100k images).
You can trigger check for previews and recreation of some missing ones by command Library-previews-render standard previews.
You wrote: "Is it 100% guaranteed that LR3 will reassociate catalogue develop module history with re-found folders and images?"
When you move images to a new drive with the procedure that I described previously, the catalog remains the same. By moving images the catalog is not changed at all. That is why you have to point Lr to the new location of the images. Before the "ponting to" the catalog has still the old location stored and does not yet reflect the new location of the images. When this happens Lr sends you "missing folder/image" messages. The "pointing to" procedure updates the catalog with respect to image location but in every other respect the catalog remains the same. So your edits are preserved.
And you wrote: "Are there any circumstances where catalogue develop history would be lost, or previews require regeneration?"
Yes there are. When you re-import images your develop history, your edits, and all else what you did in Lr would be lost - unless you saved metadata to file for every image. But even when you save metadata to file your virtual copies, your collections, and your stacking would be lost because these things are saved in the catalog only.
It is the catalog where Lr saves everything you do in Lr. When you re-import images, the images will be loaded into Lr as they are on disk but the catalog will be ignored. So re-importing brings the images into Lr again but without all the settings stored in the catalog.
Thank you Cornelia and web-weaver - I spent a couple of days fathoming and testing. Could you check out what I am doing?
I can begin to see how to archive (physically move) my images from one drive to another - meaning physically moving the images and develop settings, meta etc. I think this is a normal procedure for a lot of photographers who have to keep a working PC uncluttered by archiving to an external or network drive.
To archive my photos (RAW and JPEG) I cannot use "Export", because the Export dropdown generates additional copies or additional originals without develop settings, meta, etc.,The 'original originals' stay in original physical location also.
To archive my photos by folder or by selection with settings, I must use "Export as Catalogue". This creates a new (let's call it temporary) catalogue and imports selected files or folders and associated catalogue data into the new catalogue, and at the same time makes a new physical copy of the photos. The Export as Catalogue dialogue enables user to chose a new catalogue name, and a (let's call it temporary) physical location. This copies folderstructure\files to a subdirectory titled \Photo? Is it always a sub directory named \Photo\folderstructure\files, or is it coincidental because my original root directory happens to be \Photo ?
Nevertheless, via "Export as Catalogue" we retain original library and physically located files as-was, plus we get a new catalogue with duplication of meta and develop settings, et al, plus a physical duplicate of images in a new location - correct?
Then, if workflow was to archive by physical movement (move in OS terms), instead of archive by copy, then it would be necessary to manually delete physical files and directories from the original catalogue - correct?
Now if my archive drive has its own Archive Catalogue, I must not use Import to fetch in files and settings from the new (Export as Catalogue) catalogue generated previously. I must use "Import from Catalogue" otherwise the develop settings, meta, etc, are not imported to the archive catalogue.
After running "Import from Catalogue", if the physical file location was not where ultimately required on the archive drive, I must also delete the temporary located files, and perhaps the temporary catalogue.
This is where my testing brought me. No damage done so far. Now, when I "Import from Catalogue" a folder structure from my temporary Catalogue, LR did not import the full folder structure as there was some former remnants on the archive drive from a time before I bought LR. I guess LR cross checked meta data somehow and decide there were some unaltered files already present on the archive drive, and decided to hide those from the importation process. Luckily I had noted the original export folder/file counts and verified the same import quantities. Luckily I had not deleted any original folders/files, nor temporary catalogue or temp folders/files. By searching the Archive drive I discovered where the remnants were lurking, and actioned appropriately. Now I got a full 100% import of catalogue data and files and although they were imported as ..\Photo\ folderstructure\files I could easily drag drop and rename as I liked.
So to complete a workflow of Moving folders and files from one drive to another (move in OS terminology), I must
a) "Export as Catalogue" to a temporary catalogue and physical location.
b) note the folder/file counts for verification later.
c) "Import from Catalogue" the temporary catalogue and folder/file structure, at the same time verifying and import dialogue folder/file counts.
d) Delete original physical files and catalogue information from original catalogue
e) Rename, Drag and drop the imported folders/files as required, if the original \Photo\folderstructure\files directory structure is not exactly as required.
f) Optionally, delete temporary catalogue, and physical files.
Your description of moving image files and folders to a different drive is very convoluted and plain wrong.
Why don't you want to follow the procedure that I outlined earlier?
You can do whatever you want, but I can guarantee you that you will end up in a mess.
I think that it is the idea of "archiving images" that puts you on a wrong track. Archiving images was a technique when we had limited space on our computers and on-line external drives were not yet developed.
This technique of archiving by taking images off-line (off the computer) is outdated. In the world of external hard drives taking images off-line and "archiving" is obsolete. All images stay on-line all the time, and there is no necessity to take images out of Lr ever. The idea of "archiving" and creating a separate "archiving catalog" will only bring trouble and frustration for you. Why do you want to do this? What is the necessity? What is the advantage?
The Lr concept is so simple: All images stay in Lr forever - in one catalog. There is no necessity for archiving, there is no necessity of creating more than one catalog. If you run out of room on your computer you simply move photos to an external drive BUT the stay in Lr. They are not archived, they are not exported, they simply remain in Lr and they remain in one and the same catalog. Period.
If you want a backup for your photos get an external hard drive that can be set to RAID 1 (mirroring). These drives contain two physical disks and every image is saved to both disks, and should one disk fail, all photos can be retrieved from the other disk.
like web-weaver I am also wondering you would want to have 2 catalogs: why create an archival-catalog? why not leaving all images inside your one-and-only master catalog?
LR now can digest several hundert thousands of images inside 1 catalog, and they can be spread across all storage media. Though it is wise, as web-weaver suggested as very first thing, to have one parent-root folder on each storage drive, containing all detailed image-folders.
So I, too, would advise to just move your image-folders inside your master catalog to the destination location.
That is all what is needed.
If you indeed insist on having 2 catalogs, you need to handle several interim transportation-vehicle-catalogs, as you have outlined.
But why such fussiness?
This info is very helpful; thank you!
Question: When I keep all my photos in LR, it takes up space on my computer hard drive (which filled up this summer). So, I moved my 2011 "mother photo file" to my external hard drive. Is that bad? Then in 2012 I created a 2012 "mother photo file", which is now the main folder I have in LR. Am I doing this incorrectly? Now, I Import photos into my EHD, create a Sub-Folder in LR under my 2012 Main Folder, edit images, Export to EHD, and then Export again to computer for current use. When I don't need them on my computer, I just delete the computer Folder. So, if I have to access the Folder in LR again, I just plug in my EHD so that it "syncs" with LR. Am I doing this correctly?
Thanks in advance for your help; I'm still really new to LR!
Moving photos to an external hard drive is not only OK, it is the way to go because external HDs are usually larger than internal ones and some of them come with RAID 1 .
BUT - moving images to an external HD should NOT involve exporting these photos and / or removing them from Lr.
All your photos can and should stay in Lr no matter where they are - internal HD, external HD. There is no need to remove photos out of Lr or to export them.
I don't quite understand your workflow regarding exporting photos and exporting again.
There is no need to export any photo as long as it remains in Lr. It seems some people think they have to export a photo when the editing is done - why do they think that? I don't know, but exporting is not necessary. If you want to do an alternate edit, simply create a virtual copy. If you want to safeguard your edits, make a backup of your (edited) photos - by copying via your OS to an external HD, for instance.
Exporting a photo is only necessary in case
a) you want to send a photo by e-mail and need to create a (small) JPG for that;
b) you want to upload a photo to a website and need a JPG for that;
c) you want to send a photo to a lab for printing and you need a JPG or a TIF for that;
d) you want to send a photo to a client and need a JPG or a TIF for that;
e) maybe there's one or two other reasons but can't think of any ...
So, basically, exporting is only necessary if you want to send a photo to a different location than your own computer system.
As long as the photo remains on your system, exporting is not necessary and only creates copies that clog up your hard drive.