[Linux-ha-dev] Removal of ppp-udp option from heartbeat
alanr at unix.sh
Thu Mar 8 07:59:07 MST 2001
David Lee wrote:
> Just a quick note of caution from someone who has never yet used heartbeat
> (but will soon), and who probably won't need its "ppp". I am therefore
> completely unqualified to comment on this, so here goes(!)...
> The hitherto-called "linux-ha" is being expanded to non-Linux systems
> (think "open-ha" conceptually).
> Should one peculiar bug in one peculiar OS (Linux) be sufficient to
> warrant the removal of a potentially useful feature that might benefit
> other, less buggy, OSes?
> There may be other good reasons for its entire removal: fair enough.
> But "one bad OS-apple don't spoil the whole OS-bunch".
Since the serial option works well, and the code for implementing it
*without ppp* is smaller than the code for telling ppp what to do (much less
the size ppp itself), the advantages of using ppp are not obvious.
It is necessary to schedule pppd as a soft realtime process. If a given
machine's PPP implementation has any infinite loops in it, then the entire
machine hanging. This is generally thought to be a bad idea.
Particularly as heartbeat, et al expands to other platforms, the job of
testing it with all the potential versions of ppp that might be available on
various platforms gets much bigger, and relying on external software which
is not completely standardized in it's interfaces becomes harder.
A good question to ask is "Why is my code for actually doing the work
smaller than the code to tell ppp what to do"?
The serial code doesn't negotiate anything. As a result it starts
very simply, quickly and reliably.
Heartbeat already has packet integrity checks (as part of
Heartbeat already has a packet retransmission protocol
The serial code never has to detect (guess) that something
has gone wrong and restart a process to fix it.
-- Alan Robertson
alanr at unix.sh
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