On Wed, Feb 27, 2008 at 03:57:29PM +0200, Marcus Sundman wrote: > Nicolas Williams <[EMAIL PROTECTED]> wrote: > > On Wed, Feb 27, 2008 at 05:54:29AM +0200, Marcus Sundman wrote: > > > Nathan Kroenert <[EMAIL PROTECTED]> wrote: > > > > Are you indicating that the filesystem know's or should know what > > > > an application is doing?? > > > > > > Maybe "snapshot file whenever a write-filedescriptor is closed" or > > > somesuch? > > > > Again. Not enough. Some apps (many!) deal with multiple files. > > So what? Why would every file-snapshot have to be a file that's valid > for the application(s) using it? (Certainly zfs snapshots don't provide > that property either, nor any other backup-related system I've seen.)
With CDP you'd have thousands (and possibly many more still) snapshots a day to choose from when restoring. With backups you get to quiesce the apps/system, and you don't run them that often, with CDP the wohle point is that you don't have to quiesce the system and it runs continuously. So I see a tremendous qualitative difference between CDP and snapshots/ backups. The question remains: how to pick a CDP snapshot to restore to? How do you even know which files are relevant to whatever problem you're trying to solve via restoring to a CDP snapshot? I'm convinced that the answer is that we need new system calls by which apps can inform the system about the state of app-level filesystem transactions. Modify a few high-profile apps to support this and you've got a good chance to get momentum behind CDP (i.e., to get other less visible apps to be updated too, to get third parties to update their enterprise apps). Nico -- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
