* Matt Taggart <m...@lackof.org> [230419 04:22]: > On 4/15/23 15:35, Chris Hofstaedtler wrote: > > > > This behavior might follow the principle of least surprise, but I think > > > for > > > SSD based systems it is losing out on the benefits of TRIM/discard > > > (improved > > > i/o latency, flash wear). > > > > Yes. Also it is - to the best of my knowledge - the only way of not > > destroying possible admin configuration on upgrades. > > I can think of a few situations: > > A) installed system pre-bullseye, so not enabled by default. System does not > have a /etc/systemd/system/timers.target.wants/fstrim.timer symlink. > 1) admin unaware of it, would benefit from it, might want it > 2) admin aware of it, chose not to not have it enabled > B) installed system bullseye or later, enabled by default. If the system is > lacking the symlink, that means it was explicitly disabled by admin. > > My guess is A1 vastly outnumbers A2 and B, but that those may be non-zero. > Does the differentiation between "disabled" and "masked" make any difference > here? Would an admin that doesn't want it have explicitly masked it?
Who knows. I agree it would be nice to have it, but I cannot think of a 100% solution. > I thought of another case where it would be good to have it enabled by > default: for virtual machines that use a copy on write filesystem and set > discard=unmap to tell the virtualization that those blocks can be dropped on > discard, potentially saving a lot of disk space. fstrim.timer not being > enabled in the Debian VM hurts the virtualization host(even those not > running Debian). Yes. Enabling trim/unmap is standard practice for virtualization environments. To get good performance, you have to be in control (or at least be aware) of both the host and the guests, and the underlying storage. > I guess it's already documented in README.Debian. Maybe it would be > interesting to have something in the Bookworm release notes? Makes sense to me. I think the release notes people would want to see a patch / merge request. General advice on how to set up VMs might also want to find a place in the installation guide. Best, Chris
