Path: utzoo!attcan!uunet!cimshop!davidm From: cimshop!davidm@uunet.UU.NET (David S. Masterson) Newsgroups: comp.databases Subject: Re: Multiple DBMS servers on the same CPU Message-ID: Date: 13 Jun 90 17:36:27 GMT References: <1990Jun12.154120.3169@newkodak.kodak.com> Sender: davidm@cimshop.UUCP Distribution: na Organization: Consilium Inc., Mountain View, California. Lines: 32 In-reply-to: deal@newkodak.uucp's message of 12 Jun 90 15:41:20 GMT In article <1990Jun12.154120.3169@newkodak.kodak.com> deal@newkodak.uucp (Stephen M. Deal) writes: We are wondering what the impact on a hardware/os platform would be if we ran two (or more) DBMS servers simultaneously on the same CPU. For example if we use a vendors application which runs on the DBMS bundled with the OS and then develop our own applications on a different DBMS, what would be the performance impact. It really depends on the amount of work that each DBMS has to do at any point in time. From the OS standpoint, each DBMS is a process that the OS must service. Priorities and scheduling come into play. From within a particular DBMS, everything outside of it is competition for resources (mostly CPU or disk I/O processing time). If each DBMS had lots of work to do at any point in time, the impact would be felt just as if there was one DBMS with many other process intensive (CPU or I/O) tasks going on. It seems to me that the two DBMSs might fight for resources and therefore provide less throughput than if both applications used the same DBMS. More than likely true. A single DBMS should have an understanding of the requests that it is currently processing and expectations for processing them in order to allow it to schedule other activity efficiently. Two DBMSes have no idea what each other are doing and, so, cannot schedule tasks with the other DBMS in mind. -- =================================================================== David Masterson Consilium, Inc. uunet!cimshop!davidm Mt. View, CA 94043 =================================================================== "If someone thinks they know what I said, then I didn't say it!"