On 10-05-17 01:14 PM, John Stoffel wrote: > > Yves> * when a file is open for writing on one node, it is locked and > Yves> becomes read only on the other nodes (locking done by the NAS > Yves> device/filesystem, not the apps). > > Key.
Yes. > Yves> * replication is done as the file gets written, not afterwards. > > Umm, so what happens if I open a file for writing, truncate it, then > start writing new data. But the WAN goes down after the truncate, but > before the write of new data? And the WAN stays down and you need to > bring up the remote site now in a standlone manner and make it the > master? Good question. The wan reliability over the years has been very good, so we know from historic data that this is going to be a rare occurrence. The work flow here is that a remote cluster write to a file for hours or days... if the wan gets broken then the resulting file will not be valid and the post-processing software the user will try to use on it will choke, not unlike somebody trying to open a word document that a colleague was writing to the lan when the local network broke. > The only thing I can suggest is to use a Cluster Aware filesystem, > which can be exported locally as NFS. That *might* do the trick. But > you might have to have all your nodes running the cluster filesystem. I guess that's where the appliances make it easy, no additional administration, they take care of that. > We tried using Netapp's FlexCache product and it just didn't work out > for us. This isn't quite the same thing, in that FlexCache has a > single writeable master, and multiple read-only slaves. The idea > being that the slaves only cached the contenct that was actually used > locally. Yes we talked to NetApps and they said they did not have what we're looking for. -- Yves. http://www.SollerS.ca/ xmpp:y...@zioup.com _______________________________________________ Discuss mailing list Discuss@lopsa.org http://lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/
