mlhoff Loc: Cincinnati, OH

I have a question about making a backup of LR preview files. (Yes I know that backing this up is not really necessary but it can save time) If I use file explorer to copy the LR catalog from an internal SSD to an external SSD (Crucial X8 4tb using a USB 3 port) it copies at speeds over 100 mbs but when the previews are copied that speed goes down to low single digit mbs or worse kbs. Is this because LR (or Windows) must convert these previews to a different file format or is there some other reason these files take so long to copy? So far copying 292000 previews has taken 24 hours and it says it will need at least 12 more to finish. Thanks in advance for any help solving this mystery.

Longshadow Loc: Audubon, PA, United States

I backup about 230 Gb of files via USB drive and it takes 4 hours via a CMD batch file.
That includes only about 22,000 images files. (Docs and other files get backed up also.)
So based on a 5,000 to 6,000 files per hour, 50+ hours (over USB) doesn't sound unreasonable for 292 thousand files. Of course it depends on their size. I suppose I'm transferring about 58Gb per hour.

I've no idea of transfer speed, I just run the backup and go do other things.

CHG_CANON Loc: the Windy City

Previews are like JPEG files. They drive the Library view so you can 'see' the images in the grid view and initially into the Develop module until an updated full-sized preview is generated. These are a 'must' to actually use LR. Your virus scan is likely slowing the copy processing. Consider testing the copy speed if you (a) disable your internet connection and (b) disable the virus software and then (c) run the same copy process of the entire LR folder, the one including the LRCAT, and Previews, etc.

Additionally, consider your Edit / Catalog Settings / File Handling. What is your standard Preview Size? I use 1440 pixels for the standard and quality Medium. If you have larger / higher settings, you're creating larger files to be scanned (see above) and to be copied. Check also your discard processing of the 1:1 previews. I allow mine to be discarded after 1-week, that occurs in my weekly only LR catalog backup processing.

Finally, check your import settings. What size and type of previews are you creating at import? I build only minimal previews for a quick import. I then later build 1:1 previews from the Library menu after I've applied some initial develop parameters.

gvarner Loc: Central Oregon Coast

Can’t understand why you’d need to back up "preview" files when you already have all the originals. Why not just use LR to back up its catalogue?

mlhoff Loc: Cincinnati, OH

If that is true then why are all the items I copy so much faster, this seems to only affect the LR previews?

Longshadow Loc: Audubon, PA, United States

The catalog is just a database of the files and where they reside, it does not contain the actual images.
A catalog backup is just that, a backup of the catalog information only.

CHG_CANON Loc: the Windy City

See my earlier reply and investigate your settings and / or virus scanning.

CHG_CANON Loc: the Windy City

You don't use LR. If you did, the answer wouldn't be so unclear. LR operates on it's own internal version(s) of the image aka the Preview file(s). The Previews are created during import, and then updated during work in the Develop module. The actual image is keep as read-only reference and only reused when 1:1 previews are built / rebuilt, or the edit instructions are applied to the original during the creation of the new export file.

CHG_CANON Loc: the Windy City

The LR catalog back-up does nothing except ZIP the LRCAT file and then run RDBMS maintenance of the active LRCAT file, such as purging RDBMS entries of deleted images and the associated previews, as well as deleting 'expired' previews, based on the user's preference settings.

gvarner Loc: Central Oregon Coast

Yep, I forgot that part. I load all my photos into a folder on an external drive and then copy that folder to my HD.

Longshadow Loc: Audubon, PA, United States

You're correct, I don't use LR.

I responded regarding a "backup", not a LR question.

mlhoff Loc: Cincinnati, OH

I import the pics with a 1:1 preview, medium quality, 3840 pixels (I have a 32 inch 4k monitor) and the previews are discarded after 30 days. There are so many files because I just got back from 2 big trips (Antarctica and Iceland).

CHG_CANON Loc: the Windy City

Seems reasonable, assuming you edit new images for a month rather than a few days. Look at your virus scanning as the drag on copy speed rather than the size / count of the files being processed.

TriX Loc: Raleigh, NC

Do you mean Mb/s megaBITs/sec or MB/s MegaBYTES/sec? It matters - the difference is 8x. One might be very slow, while the other might be reasonable.

Chappy1101 Loc: Glenview, IL

Pet peeve of mine, having to guess what some folks mean, this seems to be a pretty common sloppy use of units abbreviations (incl caps and lower case prefixes also) nowadays: mb, mB, Mb, MB, gb, GB. Btw, no such thing as a milli bit😄