RE: Informix 7.24 with SAP R/3 : EMC2 : striping / fragmentation
We are also in a SAP environment using Sun E4500's connected to (4) Sun AS5000 disk arrays. (504Gig total) All the logical volumes were created using striping as per Sun's S.A.P Competency Center recommendations. No table fragmentaion is being used nor do I see a need for it. > -----Original Message----- > From: Bernstein, Rick [SMTP:rbernste@alarismed.com] > Sent: Thursday, September 10, 1998 10:49 AM > To: !INFORMIX-list (E-mail) > Subject: RE: Informix 7.24 with SAP R/3 : EMC2 : striping / > fragmentation > > We have a similar situation with SAP on AIX using SSA disks. > Based on recommendations by an IBM basis consultant, no striping > was done when the logical volumes were created. Would this > environment benefit from striping? If so, are there some SAP dbspaces > which should or should not be on striped logical volumes? > > Your informed input would be greatly appreciated. > > Thanks, > Rick Bernstein > Alaris Medical Systems > > > -----Original Message----- > From: MOPSOMER@raychem.com [mailto:MOPSOMER@raychem.com] > Sent: Thursday, September 10, 1998 12:43 > To: informix-list@iiug.org > Subject: Informix 7.24 with SAP R/3 : EMC2 : striping / fragmentation > > > We plan to move our Informix databases to an EMC2 3700 box in the > near > future. Our production database and also our two Q&A databases > (both > are regularly "overwritten" by our production database) are > around 250 > GB. Our production database is currently growing with 3 GB/week. > The > databases are only used by SAP R/3, so there are no DSS-queries. > SAP > R/3 never uses sequential scans for the larger tables, so all > accesses > are done by using one of the available indexes. The EMC2 3700 > box can > contain 128 disks of 47 GB or 18 GB and currently has 4 GB cache. > Our database server is a SUN E6000 with 14 CPUs and 4,5 GB of > RAM. > > The disks (47 GB disks for the Q&A databases and probably 18 GB > disks > for production later on) are split into multiple logical disks > (called > hypervolumes) of 4 GB. Mirrorring is done by the EMC2 3700 box > (so > mirrorring is not done by using Informix or some volume manager). > A technical guy from EMC2 recommended us to simply define two raw > devices of 2 GB per logical disk (and as such not use any > striping). > [The Symmetrix uses pre-fetching to put tracks in it's big > cache.] > > I have also recently started to fragment some of the big tables > (> 20 > GB). Fragmentation is done by round-robin as recommended by SAP. > I was always in favor of striping data over multiple disks to > avoid > over-loaded disks, so I am now worried that I could get > bottlenecks. > > QUESTION : > ---------- > Do any of you have a large OLTP environment with EMC2 and > Informix ? > If so, did you use disk striping or did you fragment database > tables ? > Any opions about striping and round-robin fragmentation with EMC2 > HW ? > > Thanks in advance, > > Mario Opsomer > Informix DBA - SAP BC Support