On 7/7/2023 12:42 PM, home user wrote:
When I try to verify a back-up, I use "diff -r". The directory trees being compared contain about 870 files (mostly binary, like PNG, JPG, and so on), and take up about 707 megabytes. The trees being compared are on the hard drive and on a USB-3 stick. When I run the "diff -r" command, it seems to finish too quickly - it seems like less than a half of a second. I saw similar results a few weeks ago comparing about 30 gigabyte trees on the hard drive vs. on a USB-3.1 stick; the results were practically instantaneous. Is diff actually checking every bit (or byte), or is it using some "short cut"?
Was this immediately after your backup/copy completed? You may be comparing against the in-memory disk caches. You may (simply) flush the in-memory disk caches to force reads from the external disk with (run as root or sudo):
sync ; echo 3 > /proc/sys/vm/drop_caches then try your diff again. _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
