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Date:      Wed, 19 May 2021 02:27:24 +0000
From:      bugzilla-noreply@freebsd.org
To:        fs@FreeBSD.org
Subject:   [Bug 251363] use unionfs as a disk-cache for NFS [feature]
Message-ID:  <bug-251363-3630-SoPWeg5Gjf@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-251363-3630@https.bugs.freebsd.org/bugzilla/>
References:  <bug-251363-3630@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D251363

--- Comment #19 from Gunther Schadow <raj@gusw.net> ---
I am certainly honored to be replied to by the one and only Kirk McKusick, =
and
of course I understand the cache consistency issue. HOWEVER, I am sure you =
will
also accept that the buffer cache is a very limited resource and generally =
too
small to hold a lot of binaries just in case.

The truth is that /bin, /usr/bin, /lib and all that good stuff hardly never
changes in a production system except for times of controlled upgrades.
Therefore the argument that the UNIONFS cache would become stale is not rea=
lly
hard hitting.

I think my approach has a very good purpose when and where applied with an
understanding of the consequences.

Finally, if you really wanted to do an unlimited cache that is kept consist=
ent,
then nothing should stop the addition of some additional update checks befo=
re
every access of the local cache on the source NFS, and likewise, writes cou=
ld
be written through to the NFS backend. In other words, NFS could have a loc=
al
unlimited size disk cache feature. But I doubt anyone would have fulfilled =
my
wish, so I went ahead and provided small improvements to the UNIONFS code to
help me with my imperfect solution that's nevertheless good enough for me.

--=20
You are receiving this mail because:
You are the assignee for the bug.=



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