Re: Clustering Support

In <51882@shamash.cdc.com> map@svl.cdc.com (Mark Peters) writes: >I'm trying to put together a table showing the database systems that >support clustering and the open-systems hardware platforms they >support it on. I've found that Oracle supports clustering via >the Parallel Server feature in V7.0, but I'm in the dark as to >whether Informix has a similar capability. In <1lv7nqINN997@emory.mathcs.emory.edu> ckipp@vth1.vth.colostate.edu (Cathy Kipp) writes: >Mark, >Yes, Informix does support clustering and on all platforms as far I can tell. >Use the create index command with the cluster feature... I fear you've caught hold of the wrong end of the stick here, Cathy. Oracle7 with the Oracle Parallel Server option supports database operations on a "cluster" of loosely coupled machines such as a VAXcluster (running VMS) or a Pyramid Valence Cluster (running UNIX). This requires the database to recognise and use the Distributed Lock Manager which co-ordinates the sharing of resources (such as disk pages in a database raw device) which are shared by all the nodes in the cluster. This then allows the database to continue processing through a node failure (eg UNIX crash or CPU failure). The surviving nodes recognise (via the DLM) that a node failure has occurred, and rollforward any committed data and rollback any uncommitted transactions from the failed node. Database application processes and associated database processes (ie sqlturbo in the Informix context) that were running on the failed node are aborted, but users can immediately log back in to the cluster and will be routed to a surviving node where they will find the database still up and running. Users attached to the other nodes in the cluster are not aware that any failure has occurred and continue processing uninterrupted. This technology means that a system crash on a database server machine becomes no more disruptive than the failure of a database client machine in a scenario where alternative database client machines are available. UNFORTUNATELY, Informix DOES NOT support clustering in this context, nor, so far as I have been able to establish, do they have any plans to do so in the foreseeable future.