Standby strategy

We are currently trying to devise a suitable strategy for maintaining a hot standby system using two clustered DEC Alphas. Two disks within each box are volume shadowed thus giving each machine visibility to all the Oracle files within the installation. We are using Oracle v7.1.5.

Up until recently we had been intending to make use of the Oracle Parallel Server option, however due to the associated costs, this solution is no longer acceptable to our client unless it represents the viable option within the project timescales.

Since we are not really using OPS as it was originally intended - for the most part the standby machine is idle - it crossed my mind that a much cheaper solution is potentially possible. Assuming the two machines are known as A and B, the strategy goes something like this; a single database instance starts up (in exclusive mode) on machine A. At failover the Oracle instance upon A is shutdown (assuming that it is still up) and a new database instance, accessing the same database, in started up upon B. Simple.

Now so long as we can guarantee that the two instances (or more precisely the two occurences of the same database instance) are never connected to the database simultaneously then we are OK. If this cannot be guaranteed then the database is in danger of being corrupted. Note that unlike two instances running upon the same machine I don't believe that Oracle will trap this on our behalf. The 2nd instance to connect will, after interrogating the control files, presumably see that there is an inconsistency and attempt to perform crash recovery.

Has anybody had any experience of implementing such a strategy ? Is it viable ? Received on Mon Mar 16 1998 - 00:00:00 CST