[H-GEN] SSHFS - Local caching and syncing

[David Seikel]

On Wed, 1 Jun 2016 13:43:36 +1000 Gary Curtis <gazilla at gmail.com> wrote:

> I just had a discussion with a third party about sshfs.
> 
> They are of the opinion that sshfs does some sort of local caching,
> such that changes to a file at the server end are not reflected at
> the client, whether or not the file is being currently edited.
> 
> This raises two potential problems...
> 1) The unrecognised changes at the server end may result in a lost
> write. 2) The local caching at the client end may constitute a copy
> of the file, breaching privacy and/or copyright concerns.

I should point out that every computer operation is a copy, there's no
such thing as a pure move.  All moves are a copy followed by a delete,
and even the delete is often just unlinking the data rather than
actually deleting the data.  Some of the time even the delete isn't
done, the data is just left to eventually be overwritten by something
else.  Maybe.

So a cache is just one more copy.  The client copied the file from the
server in the first place, it went into the cache AND a copy was sent
to the software using the file.  The software likely made internal
copies of at least bits of the file.  If the file is a document, then
the software made a copy on the screen, involving copies in the font
engine, copies in the window manager, copies in the GPU, copies on the
monitor (which also have CPUs in them making more copies), and
eventually, a copy in your head.

Not to mention copies in the various network devices as the file is
copied across the network so you can edit it.  Also not mentioned, Unix
like operating systems use any spare memory for general caching and
buffers, so more copies of everything that goes through the IO system.

Though sure in this case, some of those copies are encrypted, but not
all.

So 2) is basically the legal system not reflecting how stuff actually
works in reality.  A common flaw caused by politicians not having a
clue about the real world.

As for 1), lost client / server writes is an age old problem, doesn't
modern software have age old solutions?  If not, someone send them a
patch.  This is what file and record locks are for, they have been
around for decades.

> What does the combined wisdom of Humbug think of this...?

-- 
A big old stinking pile of genius that no one wants
coz there are too many silver coated monkeys in the world.
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