The _pre folder is used as a temporary storage location for files whose checksums have yet to be calculated.
Artifactory holds them in the _pre folder, calculates their checksums, and then moves them to their correct locations.
For any given file, if Artifactory encounters a checksum error or a move isn't possible, the file will be deleted.
If, however, Artifactory is in the midst of shutting down or the process fails (i.e, OOM errors occur, connection problems arise, the disk is full, etc.), the file may be defined as an orphan.
In the case of an orphaned file, you can safely delete any files from the _pre folder while Artifactory is down.
You can also search for any files that have been in the _pre folder for an extended period of time.
You will be able to find the _pre folder in the eventual and the cache.
While both have the same naming convention - A temp file with a prefix of dbrecord and a suffix of .bin.
Please note that the content of these is different and not related to each other.
If an exception is thrown in the eventual, then your _pre content may be deleted, but not moved. If a file is stuck in the _pre folder cache, it cannot be accessed, and even restart will not make it to be synced in some cases.
The artifactory-uploads folder (located in the $ARTIFACTORY_HOME/data/tmp folder) is used for UI uploads to Artifactory.
In turn, Artifactory will temporarily save these files before indexing them and when the deployment finishes, they will be deleted from this folder.
The work folder, also within the $ARTIFACTORY_HOME/data/tmp, is used for storing temporary indexers files during the indexing of files upon deployment to Artifactory.
After indexing is complete, the content of this directory will be deleted.