check the docs + faq about files cache #5371
Description
there are frequent questions like "why is borg slow for me, considering all my files modified" when the underlying filesystem has issues with:
- stable inode numbers
- when people do not always have the same full/absolute paths
- when they have ctime issues (like cron scripts running chown -R/chmod -R)
there are quite some related posts on this issue tracker (also see closed issues) and on the borg mailing list.
the usual way to debug / fix this is using borg create --list ... to see file status and whether a lot of files are considered modified although they should not be plus using the stat command on these files to see why borg considers them changed or has a files cache miss (if not obvious, e.g. due to full path change).
fixing the issue is sometimes out of borg scope (e.g. mounting always to same mountpoint, not doing chown/chmod by cron) and sometimes tweaking borg's --files-cache (e.g. if the source fs does not have stable inode numbers).
check our docs (esp. borg create and faq) and make them more complete / better discoverable, so less people ask these questions.