Re: Informix and SCO

Posted in 1994

Peter Wiley - Poultry — 9 Aug 1994 00:02:01 GMT — source: Informix-list mailing list archive (1991-1998)

The trouble with IDE controllers lies in their interaction with the OS. UnderWindows, they're fine. Under unix, they are fairly poor as the OS is blocked while disk i/o is occurring. The IDE controller is a blocking controller; it keeps the bus until it's finished. If your unix system is mainly servicing one user (well, very few) this isn't really noticeable. The reason caching controllers work is they cut down dramatically on physical disk i/o. There's been a lot of threads on this topic in the scsi newsgroup. I've proved it to my satisfaction; I had 2 identical machines except for HD config. The SCSI system was measurably faster under unix. Easy test is to d/l a 10 Mb file using zmodem while doing other processing. On the IDE box, every time the drive light flickered, a receive error occurred. Never happens with SCSI. Same modems etc. For intensive DBMS work on small machines, a *caching* SCSI controller is best. I just settle for an Adaptec one on all my machines.