On Sunday 17 November 2002 04:48 am, Donald Grayson wrote:
As for why these are better than software RAID? Well, there's the offloading of the RAID management from the CPU to the unit itself. What CPU usage you asked? By it's very nature, a software RAID is running from your systems CPU.
Of course the above only matters if you have a high CPU utilization. Mine are (dual CPUs) are ideling along at 2% all the time.....
If all of the configuration, management and monitoring is being done by the controller and is totally transparent to the OS it is a Hardware RAID.
Yes, this is one of the BIG advantages....
Here's a link to benchmarks comparing the Accusys 7500 to a Highpoint PCI RAID card: (snipped)
Again, performance may prove to be one of biggest advantages, especially in a heavily loaded machine. But consider alternative points: 1 Placing a very expensive controller is an otherwise slow box may not improve real-world performance much 2 Applying a similar amount of funds to your MAIN CPU(s) may allow them to yield similar real-world performance with s cheaper ide-raid card OR with software raid 3 Applying those funds to the main processor and or memory also improves performance of many other aspects of performance and improves latency of other tasks that are not disk related 4 An infinant amount of funds applied to raid controllers will never allow you to get around the slow disk IO latency (slow in terms of disk-IO's HUGE contribution to overall data access cycle). 5 A relatively modest investment in main memory can make huge improvements in performance, especially on a busy server. Therefore, my experience over the years is that buying raid controllers for the ease of setup and convenience makes a great deal of sense if they are CHEAP, but allocating dollars elsewhere is more advantageous for overall system performance. I've purchased some of the high performance raid controllers (SCSI in my case) and saw minimal improvement in overall performance, easily outstripped by doubling main memory. - where's my spell checker... -- _________________________________________________ No I Don't Yahoo! And I'm getting pretty sick of being asked if I do. _________________________________________________ John Andersen / Juneau Alaska