On Wed, Sep 13, 2006 at 06:37:25PM +0100, Darren J Moffat wrote: > Dale Ghent wrote: > >On Sep 13, 2006, at 12:32 PM, Eric Schrock wrote: > > > >>Storing the hostid as a last-ditch check for administrative error is a > >>reasonable RFE - just one that we haven't yet gotten around to. > >>Claiming that it will solve the clustering problem oversimplifies the > >>problem and will lead to people who think they have a 'safe' homegrown > >>failover when in reality the right sequence of actions will irrevocably > >>corrupt their data. > > > >HostID is handy, but it'll only tell you who MIGHT or MIGHT NOT have > >control of the pool. > > > >Such an RFE would even more worthwhile if it included something such as > >a time stamp. This time stamp (or similar time-oriented signature) would > >be updated regularly (bases on some internal ZFS event). If this stamp > >goes for an arbitrary length of time without being updated, another host > >in the cluster could force import it on the assumption that the original > >host is no longer able to communicate to the zpool. > > That might be acceptable in some environments but that is going to cause > disks to spin up. That will be very unacceptable in a laptop and > maybe even in some energy conscious data centres. > > What you are proposing sounds a lot like a cluster hear beat which IMO > really should not be implemented by writing to disks.
Wouldn't it be possible to implement this via SCSI reservations (where
available) a la quorum devices?
Ceri
--
That must be wonderful! I don't understand it at all.
-- Moliere
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