On Mon, Mar 04, 2019 at 06:44:15PM -0700, Theo de Raadt wrote: > Z Ero <zerotetrat...@gmail.com> wrote: > > > Hello, > > > > Curious if there is a facility to save system memory state to disk for > > recovery such as is done the ZZZ (hibernate) command without actually > > powering down? Could be useful to return to a previous active memory > > state for devices that are not on UPS or not closely monitored but do > > preform non-scripted batch work. > > > > So, for example if there is a transient power interruption on > > 03-05-2019 at 12 AM the device could be configured just to reboot to > > the state it was in at 03-04-2019 at 12 AM where it was doing similar > > work. I don't mean load a file back up but reload a previous active > > memory / process state as if returning from hibernate. > > > > Thus to enable this hibernate style dumps would be saved periodically > > by cron for example. > > > > I understand that for some dumping active memory to disk without > > powering down might present a security concern but this is not a > > problem for my application. > > What you are asking for is impossible to do correctly, because files > will be open. As a result, the filesystem image you return to will be > incoherent with respect to the open vnodes. > > I mean, it can be done. It just will have so many artificial deficits > at the low-level that it won't suit the high-level purpose you intend > fully. >
If one really wanted to do this, the right approach would be to start with filesystem and memory snapshots in vmm/vmd. I think the former can be done with enhancing qcow2, and the latter is basically already done (via vmctl send). I await OP's diff to implement this. -ml
