John R Pierce wrote: > absolutely CRITICAL to any SAN implementations is that the storage > controller (iscsi target, be it openfiler or what) remain 100% rock > solid tsable at all times. > > you can NOT REboot a shared storage controller without shutting all > client systems down first (or at least unmounting all SAN volumes) > > its non-trivial to implement a high availability (active/standby) > storage controller with iscsi. very hard, in fact. > > Dell have recently announced a product that may help a lot with this they call it Virtualized ISCSI devices see http://www.cns-service.com/equallogic/pdfs/WP910_Virtualized_iSCSI_SANs.pdf > commercial SANs are fully redundant, with redundant fiberchannel cards > on each client and storage controller, redundant fiberchannel switches, > redundant paths from the storage controllers to the actual drive arrays, > etc. many of them shadow the writeback cache storage so if one > controller fails the other one has any write cached blocks and can post > them to the disk spindles transparently to maintain complete data > coherency. Trying to achieve this level of 0.99999 uptime/reliability > with commodity hardware and software is not easy. > > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > >