-- Thomas Strandenaes University of Tromsoe NORWAY #2 >How can we organize our disks so that we can optimize disk access >and reliability? The RAID tradeoffs can be represented by a triangle where you can chose among performance, availability and cost. If cost isn't a significant issue, use host based mirroring and striping across as many I/O adapters as you can manage. If more convience is desired at a slight cost in availability use controller based mirroring and host based striping. If the I/O load is read-mostly, RAID-5 is a fair price trade-off for better cost. As the I/O load has more writes, RAID-5 becomes a poor choice. If the performance of the page/swap space is going matter, get more memory. Benchmark the difference between segregating the operating system, log files, table spaces, etc by controller or by striping off them across multiple controllers. >Can we use the raw disk/Async I/O function with the HW RAID controllers? The operating system shouldn't know the difference between a simple disk behind a controller and a RAID-5. It may want to in order to allow for state transition times after member failures, but doesn't need to. >Is Ultra SCSI the way to go? You'll be hard pressed to find current generation SCSI disks that don't support Ultra speeds. For adapters and controllers, take advantage of the extra performance they may offer. Alan Nabeth #3 Wayne, Just a couple of thoughts, as I am pushed for time at the moment, I will be glad to carry on this discussion at length with you next year ;-) I would stay away from RAW disk, unless you are planning to run Oracle Parallel Server, which requires it... I would suggest AdVfs filsystems and RAID 5, depending on your controller configuration, you mentioned 3, but fail to describe HSZ KZPSA Storage works involved or local disk, although at 90 GB I have to assume some external disks... Randall R. Cable *********************** Wayne Sweatt Principal Software Analyst Litton / PRC 505.827.9288 ***********************Received on Wed Jan 06 1999 - 22:02:29 NZDT
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