Re: Informix data fragmentation or RAID disk

My understanding is that RAID has a place in performance where the array appears as a single device to the database. RAID done correctly gives you a greater cylinder depth - Less mechanical head movement in order to perform disk reads and writes. Disks are a lot faster when access requires an electronic disk head switch as opposed to a mechanical disk head movement. Also Informix 7 supports read from mirrors. So if you have two disk arrays, one for the primary and one for the mirror, each on its own disk controller, you have two possible channels for any given read. If one channel (disk and controller) is busy, the database can go to the other in order to satisfy the read. Redundant read paths is perhaps why Informix recommends database mirroring over hardware mirroring. In article <49cu7c$l7s@cssun.mathcs.emory.edu>, cherylk@spamis.jcdc.doleta.gov wrote: > Please respond to this via the informix-list. I am also interested in this > topic. > > Thanks > Cheryl Kendricks > E-mail address: cherylk@spamis.jcdc.doleta.gov > On Wed, 22 Nov 1995, Ben Van Truong wrote: > > > We are about to upgrade our Informix system to 7.11UC1. One of feature > > provided by Informix 7.x is the capability to partitioning the table into > > multiple dbspaces. I am hoping to use this feature to improve I?O performance. > > What I am not sure is how the Informix table fragmentation works in conjunction > > with hardware striping using RAID devices. Your comment, suggestion is greatly > > appreciated. > > > > -- charlie_sadler@mathworks.com