Quoting Matt Helsley (matthltc@xxxxxxxxxx): > > On Wed, 2008-07-16 at 14:26 -0700, sukadev@xxxxxxxxxx wrote: > > Serge E. Hallyn [serue@xxxxxxxxxx] wrote: > > | Quoting sukadev@xxxxxxxxxx (sukadev@xxxxxxxxxx): > > | > Serge E. Hallyn [serue@xxxxxxxxxx] wrote: > > | > | Quoting sukadev@xxxxxxxxxx (sukadev@xxxxxxxxxx): > > | > | > > > | > | > cryo does not (cannot ?) recreate files if the application created > > | > | > > | > | I think that's for the best. > > | > | > > | > | Don't you? > > | > > > | > I can understand that configuration or data files should exist, but > > | > not sure about temporary or log files that an application created > > | > upon start-up and expects to be present. Should the admin find > > | > out about them and create them by hand before restart ? > > | > > | I think the admin should have set the destination environment such that > > | the task is restarted in the same network fs in the same directory, with > > | no files having been deleted. > > [Assuming Serge meant: s/network fs/network, fs,/] Well no I meant a network filesystem - at least if you're migrating apps around a cluster. > > or new files created ? For instance if the application was checkpointed > > before it created a temporary file with O_EXCL flag, that temporary > > file must not exist when restarting ? > > I think that's not a problem given my assumptions above. The filesystem > that the application restarts in would be the same because the admin > should have set up the restart environment as Serge suggested. The admin > can't rely on restart in an alternate environment. However, given > knowledge of the application and environment, using an alternate > environment may be a risk the admin is willing to take. Yup. But Suka is right that in the case of the checkpointed app continuing to run for a bit before being killed and restarted, it could get out of whack with respect to the file system. > > | Am I wrong? > > > > So we take a snapshot of the FS and checkpoint the application. Do they > > need to be atomic ? > > If all the applications in a container are frozen then I think we can > get fs snapshots consistent with checkpointed applications. > Otherwise, yes, I think we'd be gambling that the checkpointed > application isn't interacting with another, running, application via an > intermittently-shared file. What fun :) I wonder whether the experience of users of c/r on sgi and cray could teach us anything here. -serge _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
