On Mon, Sep 21, 2020 at 10:14 AM nl6720 wrote: > I wanted to know why the "issue_discards" setting isn't enabled by > default. Are there any dangers in enabling it or if not is there a > chance of getting the default changed? > > Also it's not entirely clear to me if/how "issue_discards" affects thin > pool discard passdown. > Historically, there have been dangers. Even today, there might still be dangers - although, I believe Linux (and other OS) may disable the feature in hardware which is known to behave improperly. If you do research and ensure you are using a good storage drive, there should not be any problems. I enable issue_discards on all systems I work with at home and work, and have not encountered any problems. But, I also don't buy cheap drives with questionable namebrands. It's pretty common for settings such as these to be more conservative, to ensure that the users who are willing to accept the risk (no matter how small) can turn it on as an option, and the users who are unaware or might not have evaluated the risk, cannot blame the software vendors for losing their data. In the case of LVM - it's not LVM's fault that some drives might lose your data when discard is sent. But, users of LVM might blame LVM. -- Mark Mielke