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@redhat.com

quoted

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