Re: RAID5 vs. JBOD for informix online

Paul Kocsis (pkocsis@earthlink.net) wrote: : Thank you out there for being so much help to me.....I have one more : dilemma. I am migrating my current Informix database from one Sun Ultra-2 : to another. I also have a DataDock 7000 for my new machine. My : application is OLTP where reading records quickly is paramount! I am using : Informix online 7.22. The DD7000 will be used only for informix raw space. : Will I get better throughput with RAID5 or JBOD (I realize that there are : many other factors which will affect my performance, like how well my code : is written, how well my indexes are set up....etc.) : If I use RAID5, do I still break up root space, log space, temp space, and : data space into separate DBSPACES/chunks?? Or is this practiced : defeated/nullified by the RAID5. I like the idea of the RAID5 and "if I : have a head crash on one disk...." but I really need to think soley of : performance. I'm confused as which is the best way to utilize my DD7000 : for Informix space. The main cost for RAID5 is in writing speed. If you have a heavy read-centric system, RAID5 may make sense to you. As a matter of general tuning, I'd still try to put anything that gets a lot of writes on the JBOD, not RAID. If your RAID box allows you to set up partitions with different RAID levels, you're home free. PUt it all on the new box. If not, try putting these on your regular Sun raw filesystems: rootdbs logical log buffer physical log buffer maybe your log files, if you have enough space If you want the safety of RAID, you might want to mirror these spaces, using either Informix or hardware mirroring. RAID5 will totally negate any benefits from disk fragmentation. You should just throw everything into the RAID5 and let RAID sort it out. I've seen doubling or tripling of read performance in some RAID5 installations. I've also seen write performance reduced by a factor of five in some very bad cases. Your mileage may vary. : Thank you!!! : Paul Kocsis : pkocsis@earthlink.net -- --------------------------------------------------------------------------- Joe Lumbley(jlumbley@netcom.com) author of: "INFORMIX DBA Survival Guide" Slaving away on "INFORMIX DBA Survival Guide, The SQL", available late 1998 from Prentice Hall/Informix Press. ---------------------------------------------------------------------------