If the machine mounting the file and doing the tail has read from the
file and there is new data added in that last block and because of the
rate the data is coming into the file the timestamp on the file does
not change then the client nfs host will not know that the last block
has changed and will not know to reread it (it is already in cache).
If it is this bug/feature nfs has worked this way I think pretty much
forever at a larger scale (2 hosts each writing every other block, if
the timestamp does not change then each node will see the others
blocks as empty because of cache, at least until the timestamp changes
from what it knows it wrote). The trick my previous job implemented
was to make sure the timestamp on the file moved ahead at least one
second so that the clients knew the file changed. but if tail is
actively reading it while things are getting written into it I don't
see a way it would be able to work that well.
What you are describing sounds like a variant of this issue.
On Fri, Jun 2, 2017 at 5:36 AM, Eyal Lebedinsky <fedora(a)eyal.emu.id.au> wrote:
> On 16/04/17 17:13, Eyal Lebedinsky wrote:
>> I asked on AskFedora and got no response. Hoping this list is more active.
> I last (17/04) reported the problem on redhat bugzilla
> I got no reaction since. I updated the report with a test script and also
> verified I have the same
> problem using the latest f25 (4.11.3-100.fc25). See the details there.
> Is the bugzilla active at all?
> Does anyone have a server running an old kernel (3.8, 3.9) that they can
> test against?
> I would like to confirm that this is not just my own setup having the issue.
> Eyal Lebedinsky (eyal(a)eyal.emu.id.au)
> Eyal Lebedinsky (fedora(a)eyal.emu.id.au)
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