Re: Veritas Striping for OLTP?

In article <35DDD6B7.C9EE4B2C@fmr.com>, Michael Benveniste <mike.benveniste@fmr.com> wrote: > Does anyone have experience with the use of Veritas striping on Informix > databases? We intend to use Informix in OLTP fashion, going after data > with indexes. We have few scan/join type queries. We would like to make > the lives of our DBA's simple and try to layout the data over striped > disks, separating data from indices. Beyond that we will just rely on > striping to give us a performance boost. > > My Informix SE says that striping is a bad idea, but his experience has > been on large DSS systems where explicit placement across different disks > and use of parallel queries helps performance. I'm not sure individual > placement of tables is necessarily that important in an OLTP application. > > Any ideas? Comments? Thanks and regards, > ---------- > Michael Benveniste > mike.benveniste@fmr.com > > Any comments or statements made are not necessarily those of Fidelity > Investments, its subsidiaries, or affiliates. > Michael, I am a Sr. DBA managing large (> 1 tb) Informix OLTP dbs. We use Veritas striping and mirroring (RAID 10.) For down and dirty oltp using indexes, its great. We round robin all our table data (many in excess of 300 M rows) and have all of our indexes in a single dbspace. Your assumption with what your Informix SE said is correct. This configuration will not work optimally (but it will work) for DSS type queries. In addition, large multi-table joins have a somewhat diminished performance, even if they use indexes. If your primary need is OLTP but you still must maintain a strong DSS type environment, you might try using RAID 10 with veritas striping/mirroring and an expression based fragmentation scheme for the data and indexes. This would give you the ability for multiple threads when performing DSS type queries as well as more threads for multi-table joins. The downside of this is that it is harder to maintain (all of the frag expressions.) If DSS type query performance is not a factor but you have a significant amount of multi-table joins that are critical, you could try round-robin'ing your data and using expression based fragmentation for your indexes. This would give a better performance for those multi-table joins and is not as terrible to maintain. If DSS type query and multi-table join query performance is not a factor, I would go with the scheme we use: round-robin your data in n buckets and use one dbspace for indexes. This by far is simpler to maintain since you do not have to watch frag expressions as they grow and this will deliver the OLTP performance you need. Additionally: Are you considering "hot spares" where veritas will automatically migrate a disk slice to a spare drive/slice in the event of problems? It helps with redundancy but watch out for the long sync times when disk trays or controllers go south. If you have any questions, feel free to email or call. Gary D. Cherneski Senior DBA/Consultant (work email): Gary.Cherneski@MCI.Com (work phone): (719) 535-3633 (personal email): garyc@rmi.net -----== Posted via Deja News, The Leader in Internet Discussion ==----- http://www.dejanews.com/rg_mkgrp.xp Create Your Own Free Member Forum