On Sat, 07 Feb 2015 11:27:11 +0000, The Real Doctor
wrote:

On 06/02/15 22:29, Tim Watts wrote:
Moving a client device (or several) around with intermittent (say 80%)
Internet connectivity whilst having access to files which are ultimately
mastered on a central server and can be backed up from there.

We accept files may not be available when net connectivity is non
existent, but those that are (cached) should be handled gracefully and
replicated correctly.

There was a time when Microsoft had Briefcases that provided similar
functionality, but, although I had this working between my PCs running
W98 at one time, I had to disable it, and the sort of reasons I did so
might be more widely applicable ...

For one thing, each sync always seemed to take an absurdly long time.

Databases were a particular problem. At the time I had a couple of
Access databases, and because they had to be synced record by record
or field by field (I can't remember which) that would ratchet up the
time taken even more. Further, one of the database copies had to be
'master' and the others 'slaves'. If the master became corrupted, it
was supposedly possible to promote one of the slaves in its place, but
in reality it wasn't always possible to do so.

Dragging and dropping a file into the Briefcase had an unwelcome
side-effect, the details of which I cannot now remember, but ISTR that
it arose from the fact that the Briefcase mechanism would instantly
try to replicate it around, leading to losing control of the PC while
the CPU maxed out doing it.

These days I find DeltaCopy, a CygWin version of rsync, to be much
better, though of course it doesn't replicate databases field by field
or even record by record. Also, I needed to replace a DLL to get it
to handle correctly files with foreign characters in their names.
Also, I have to run chown/chmod afterwards on the server, to give the
files the correct permissions to be available via the Samba shares -
it's always struck me that there's probably a way of doing this
automatically on a file by file basis, but I've not yet investigated
thoroughly enough to find one.

Isn't that what dropbox does?

Well, in theory yes, but on my Android phone, I find that even things
marked as favourites, for which local copies are supposedly stored,
might not actually be so local - it's difficult to be certain one
way or another, because Dropbox doesn't work on a phone the same way
as it does on a PC. For example when I reach the supermarket my
weekly Shopping List always takes some time to load; it appears to be
downloadng slowly over the phone network from the server rather than
loading quickly from a copy on the phone. When I examine the phone's
memory, I don't find the same folder hierarchy as I do on my PC, and I
can't tell whether there's really a local copy there or not.

It's not helped by the fact that on a phone Dropbox is far more
difficult to configure. On a PC, via your local LAN, you can pre-copy
all the files into a suitable directory on a new PC, and then install
Dropbox, telling it which directory to use. It then very quickly
examines the indicated folder and marks it up to date. This means you
get the files stored where YOU want them - not where Dropbox, or,
heaven forbid, Microsoft thinks you ought to put them - and the
first sync takes a minute or two instead of an hour or two.

Really I'd like to be able to do this on my phone. I could then just
copy the lot via the USB cable, designate the folder, and let Dropbox
spend a minute or two deciding that there was nothing else to do.
Subsequently my Shopping List, etc, would load in an instant the way
it does on a PC. However, in the real world, I have to spend more
time than it's worth trying to decide which are most important and
designating those as favourites in the hope that they may, or may not,
be stored locally.
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