RE: HP vs Informix mirroring

> Funny, but we had exactly the same set up: RAID-5, HP/UX 10.20 and Informix > 7.23UC1, but performance decreased when we went to a (Informix) software > mirroring scheme (Raid 1/0? - I can never remember). I'm fairly convinced > this was because it has a capacious and expensive 3rd party disk controller > and cache. My gut feeling would be to avoid RAID - 5 like the plague - > mainly due to the inability to use table fragmentation. RAID 5 does incur overhead, no argument there. Regardless, it does make sense for SOME sites. The overhead applies primarily to disk writes (inserts and updates), so for data warehouses or other systems with primarily read access it may be appropriate. Agreed, RAID 0/1 will run faster, but the additional hardware costs for full mirroring may outweigh the improved write performance, for some people. As to the fragmentation issue, with a truly large database, you probably have multiple RAID arrays, and you can fragment across multiple arrays, rather than multiple disks. > One interesting thing that came up on this particular machine is that in > 7.23+, on an HP/UX 10.20 box, with an ANSI database, performance dies, by a > factor of many THOUSANDS, when you have more than about 4 million records in > the database. Apparently, Informix loses all grip of query paths, and starts > doing sequential scans all over the place. I assume you ran SET EXPLAINs before and after, and that is how you know it's now doing sequential scans. I know it's a basic question, but have you updated statistics according to the release notes? Is there any way you can create a test database of similar size but with non-ANSI logging, to see if the performance drop is limited to ANSI databases? > Also, with post 7.23x ANSI databases, dbschema crashes the engine when run. Only ANSI databases? What did Informix support say? > AND (will this list never end?)there is a bug in HP/UX 10.20 that crashes > (i.e. reboots) the whole box after a few minutes of usage in 7.23.uc4+. Is this a known bug, with an Informix bug number? I'm running 7.23.UC6 on HP-UX 10.20. How many minutes is "a few minutes of usage"? Mine has been staying up all day for weeks. We do bring it down each morning, but I also have several test databases with similar setups that have been running for 3 weeks. "onstat -" gives "INFORMIX-OnLine Version 7.23.UC6 -- On-Line -- Up 21 days 00:52:55 -- 11352 Kbytes". I'm not doubting that you have experienced the problems you mention, I'm just wanting to see if there's an Informix bug that may affect me. One possible difference is logging mode - you mention ANSI logging several times earlier, and I don't use that mode. Were the databases on the rebooting machines also ANSI? > Ahhhh Informix. > > Kevin Crisp Mark Collins mcollins@us.dhl.com Everybody at some level realizes that the calendar is a fairly arbitrary thing, invented by humans, for reasons that have more to do with how committees are structured than with anything that's really happening in the heavens. And yet people look at the fact that the calendar is about to turn 2000, and assume there's some deity who thinks that the base 10 counting system is pretty darn important, and make all sorts of predictions of doom and gloom as a result. To me, that tells you everything you need to know about human beings -- and a whole lot about the market for the NC. Scott Adams, creator of _Dilbert_