On Thu, 2019-09-05 at 14:51 -0400, Ray Strode wrote: > Hi, > > On Thu, Sep 5, 2019 at 2:37 PM Steven Whitehouse <swhiteho@xxxxxxxxxx > > wrote: > > The original reason for the mount notification mechanism was so > > that we > > are able to provide information to GUIs and similar filesystem and > > storage management tools, matching the state of the filesystem with > > the > > state of the underlying devices. This is part of a larger project > > entitled "Project Springfield" to try and provide better management > > tools for storage and filesystems. I've copied David Lehman in, > > since he > > can provide a wider view on this topic. > So one problem that I've heard discussed before is what happens in a > thinp > setup when the disk space is overallocated and gets used up. IIRC, > the > volumes just sort of eat themselves? > > Getting proper notification of looming catastrophic failure to the > workstation user > before it's too late would be useful, indeed. > > I don't know if this new mechanism dhowells has development can help > with that, My understanding is that there is already a dm devent that gets sent when the low water mark is crossed for a thin pool, but there is nothing in userspace that knows how to effectively get the user's attention at that time. > and/or if solving that problem is part of the Project Springfield > initiative or not. Do you > know off hand? We have been looking into building a userspace event notification service (for storage, initially) to aggregate and add context to low- level events such as these, providing a single source for all kinds of storage events with an excellent signal:noise ratio. Thin pool exhaustion is high on the list of problems we would want to address. David
