Why does Lightroom create .lrtester.tmp files in the cache Originals folder every 4 seconds?

[Jason Pursell]

Apologies if this is a dumb question. Maybe this is default behavior? I'm new to macOS (this week). I don't remember this happening on PC, but it could have and i just never noticed it.

ISSUE:

When Lightroom is open, i see the activity light on my external drive flash about every 4 seconds. I'm not doing anything in Lightroom at the time. This continues to happen unitl I quit Lightroom. My Originals cache is on an external drive.

Some preliminary investigation shows that Lightroom is accessing the drive and writing temporary files called  .lrtester.tmp into the cache Originals folder.

Is this expected? Thank you.

Some partial output from the fs_usage command (my external drive is named Media_Main)

 sudo fs_usage -w | grep "Volumes/Media_Main"

10:31:34.445864  stat64                                 /Volumes/Media_Main/Adobe/Cache/Lightroom CC/[deleted for privacy]/originals                                                                               0.000032   Adobe Lightroom.80750

10:31:34.446364  open              F=28       (_WC_T_________)  /Volumes/Media_Main/Adobe/Cache/Lightroom CC/[deleted for privacy]/originals/.lrtester.tmp                                                         0.000271   Adobe Lightroom.80750

[Claire H. · Accepted solution]

Hi @Jason Pursell, Thanks for reaching out to the forums! The .lrtester.tmp files that Lightroom creates in the cache/Originals folder are temporary test files used by the app to verify write access and performance of the storage location (especially cloud-related or external storage). These files are typically created and deleted frequently (about every few seconds) to ensure Lightroom can reliably store and sync originals without data loss or corruption.

Lightroom tests disk availability and write speed as part of Adobe's internal checks to ensure your originals are safely written to disk or cloud cache. You might notice this more if your cache location is on an external drive, networked storage, or slower SSD.

While there's no official setting to disable this behavior, as it's part of Lightroom's built-in data integrity checks, however, you can make sure Lightroom is up to date, and you can also try setting your cache location to a faster internal drive to reduce frequency or impact. Hope this helps! ^CH

[Jason Pursell]

Thank you very much for taking the time to provide a detailed answer.