On Wed, 1 Feb 2023 at 17:13, emanuel stiebler via cctalk <cctalk@classiccmp.org> wrote: > > On 2023-02-01 10:56, Warner Losh wrote: > > > > On Wed, Feb 1, 2023 at 1:41 AM emanuel stiebler via cctalk > > <cctalk@classiccmp.org <mailto:cctalk@classiccmp.org>> wrote: > > > retension in case of power off. > > If the power is applied all the time, the internal controller "can" > > check the quality of the cells automatically (but this really > > depends on > > the controller, controller version, and the OS has to chose the right > > strategy. And the controllers improved a lot lately) > > > > > > The OS might not have a choice. All the SSDs that I've used in the > > past decade at $WORK have not exposed any of this to the host, not > > even enough stats to know when it's going on in real time... let alone > > the ability to pause these operations for a little while until we're off > > peak for the day... > > But you should be able to choose (at least on controllers I know) if you > like to go for automatic or manual refresh. > > If you go for the automatic, it could happen that the drive decides to > scan the drive, when your're busy and going nuts waiting for the drive > (you can also define on newer drives how many block to check per run) > > If you're going for the manual refresh, just make sure you really run it > one day. But, you should be the one who knows, when your computer isn't > busy ...
That reminds me (looks at 43.5T of zfs pool that has not had a scrub since 2021). It can be nice to have a filesystem which handles redundancy and also the option to occasionally read all the data, check end to end checksums (in the unlikely case a device returns a successful read with bad data), and fixup everything. Does not eliminate the need for remote copies, but gives a little extra confidence that the master copy is still what it should be :) Its currently all on spinning rust, but I imagine zfs scrub should map nicely onto refreshing SSDs with "read everything you care about, write only on fixing up data" (in the unlikely event I can ever afford sufficient SSD storage) David
