Re: Oracle Parallel Server

Parallel Server works, but it has its limitations:

1. Parallel Server relies in part on a vendor provided lock manager programs, ie, one on each machine that talk to each other. It is possible for these two or more programs to fail to recognize the other has failed. Eventually enough user calls come in that somebody checks out the system and someone with root authority can wake up the lock managers.
2. When one system dies the other will lock up while it performs backout of all in-flight transactions. This time varies based on system size and load, and should not be a serious problem. You just need to be aware of this.
3. Oracle and UNIX do not communicate UNIX resource problems very well and a lack of UNIX resources for the lock manager process can bring Oracle down real quick. The hardware vendor provided lock managers need a good sized chuck of memory. If the DBA bumps the number of Oracle GC locks up without the UNIX or VMS administrators being in the loop, oh well!
4. Unless your system was designed very well with plenty of spare resources the DBA group will still need windows to rebuild indexes, relocate tables, and so forth. Being parallel does not allow the tables to be used from one machine while the same database objects are maintained from the other.

Parallel Server works reasonably well and can allow one set of non-distributed tables to be accessed by a much larger group of users than one peice of hardware could ever support. Just be sure to read up on parallel server lock configuration and separate your tables and indexes based on instance (machine) access as best you can to reduce pinging.

Hope this helps, we have been running parallel for close to a year.

Mark Powell -- Read at your own risk. Received on Sun Mar 10 1996 - 00:00:00 CET