[linux-lvm] Option to silence "WARNING: Sum of all thin volume sizes exceeds the size of thin pool"
zkabelac at redhat.com
Tue Sep 19 15:30:44 UTC 2017
Dne 19.9.2017 v 16:14 David Teigland napsal(a):
> On Tue, Sep 19, 2017 at 01:11:09PM +0200, Zdenek Kabelac wrote:
>> IMHO the most convenient in my eyes is a usage of some sort of 'envvar'
> I think we're looking at the wrong thing. The root problem is what we're
> warning about, not that the warning is being printed. It doesn't make
> sense to warn about the inherent nature of things. When peole create a
> linear LV, we don't print a warning that it's not redundant. By warning
> that the pool is overprovisioned, we also mislead people into thinking
> that this is what they should worry about, when in fact it's free space in
> the pool which is the real thing to worry about. So I think the message
> should be dropped and replaced with something more useful.
The main purpose of the Warning is to really warn user there is NOT configured
auto-extension of thin-pool (so no threshold is setup) - so thin-pool is not
set-up in 'preferred' way (so when user counts with the fact the thin-pool
can grow and auto-extension is enabled - the warning is not printed).
I think it's really useful to give this information to the user - since from
my experience with users - many of them are simply unaware of the fact when
they take 3 snapshots they may need 3x more space of the origin volume.
So in the case users do want to have 'critical' volumes always 'safe' from
out-of-space condition - the message tells them when pool can't cover all
space for all thins.
Even in this list - people tend to think it is really an easy to just drop
snapshots like with old-snaps and they even think it will happen auto-magically.
So IMHO we are better to give user really good info about what is going on.
Once we provide more secure mechanism - we may possibly change the time and
actual printed message.
Skilled user just ignores the message - so is the major problem with it ?
Is it the 'severity' - so the message should be prefixed with "NOTE:" instead
of "WARNING:" (log_warn() -> log_print_unless_quite())
We have number of similar messages for other cases, so it's relatively common
in lvm2 to give some guidance messages to users - just this one gets some
extra tension (i.e. we can open similar discussion about handling duplicates
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