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Ortwin284191255cpu
Known Participant
August 6, 2025
Answered

Previews.irdata Back up not possible

  • August 6, 2025
  • 2 replies
  • 183 views

Mac Book Pro M1 internal 1T SSDI (free space 250 GB) 16 GB RAM Sequoia 15.5. LRC Version 14.4 Camera Raw 17.4. I wanted to delete Lightroom Catalog previews.irdata, which took up 192 GB. To be on the safe side, I wanted to make a backup on an external SSD (format exfat) with 850 GB of free storage space beforehand. At around 180 GB, I received an error message saying that there was not enough storage space!?! The external SSD was full!!! On another attempt, everything was supposedly copied, but Finder showed that only 32 GB of 192 GB had been copied. Renaming it to previews_OLD.irdata did not change anything. Furthermore, despite renaming it, no new previews.irdata was created when LRC was started. I still only have previews_OLD.irdata. What do I need to do so that I can save the 192 GB to an external SSD  so that I can delete it from my laptop? 

Correct answer Conrad_C

I would not bother with the goal of backing up the previews.lrdata file. I treat that file as a fully expendable cache, which is exactly what it is. A 192GB previews file would take too much space on my backups that would be much better spent on backing up valuable files that are irreplaceable. I would not back up or rename the previews file, I would just delete it without looking back.

 

By the way, my previews file will never grow to anything approaching that size again, because I now use the relatively new setting to limit the size of the previews cache. I used to throw it out after it became more than 30 or 40GB, but now it just limits itself thanks to the setting. I would have thrown out the previews cache long before it reached 192GB...I just don't have that much free space on my MacBook Pro.

2 replies

Conrad_C
Community Expert
Conrad_CCommunity ExpertCorrect answer
Community Expert
August 7, 2025

I would not bother with the goal of backing up the previews.lrdata file. I treat that file as a fully expendable cache, which is exactly what it is. A 192GB previews file would take too much space on my backups that would be much better spent on backing up valuable files that are irreplaceable. I would not back up or rename the previews file, I would just delete it without looking back.

 

By the way, my previews file will never grow to anything approaching that size again, because I now use the relatively new setting to limit the size of the previews cache. I used to throw it out after it became more than 30 or 40GB, but now it just limits itself thanks to the setting. I would have thrown out the previews cache long before it reached 192GB...I just don't have that much free space on my MacBook Pro.

    dj_paige
    dj_paige
    Legend
    August 6, 2025

    First, it is previews.Lrdata, not irdata

     

    There's really no need to make copies of previews, as Lightroom Classic will re-create the previews as needed (and you don't need to tell LrC to do this, it happens automatically). So if you want to get rid of the previews by deleting them, you can do that. But I wouldn't make a copy of the previews.

     

    PS: yoour terminology is confusing, it is not a backup if you plan to delete the originals. A backup means you plan to keep two (or more) copies on different disks; but in your plan you will wind up with one copy after deleting the original previews.

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