On September 13, 2006 6:44:44 PM +0100 Darren J Moffat <[EMAIL PROTECTED]>
wrote:
Frank Cusack wrote:
Sounds cool! Better than depending on an out-of-band heartbeat.
I disagree it sounds really really bad. If you want a high availability
cluster you really need
a faster interconnect than spinning rust which is probably the slowest
interface we have now!
But fast enough ... it's the same speed as disk access. Why would you
test something ELSE other than the actual resource you're trying to
manage, where possible.
e.g. if you have a web server that does db queries, to monitor it you
have to perform an http query that hits the db.
You'd typically have a dedicated link for heartbeat, what if that cable
gets yanked or that NIC port dies. The backup system could avoid mounting
the pool if zfs had its own heartbeat. What if the cluster software
has a bug and tells the other system to take over? zfs could protect
itself.
And anyway, unless you're exchanging state, heartbeat data is tiny
(service1: ok; service2: ok; service3: ok) and even a serial link
is good enough.
-frank
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
