Re: High lngspins - IDS 9.30 UC2

On Mon, 20 Oct 2003 17:38:27 -0400, Richard Kofler wrote: Just a brief note: I'd like to see a 6 disk (3pair) RAID10 versus the 4 drive RAID5 for apples to apples read performance numbers. As Richard notes, one cannot expect 2 RAID10 pairs to out perform the (effectively) 3-data-drive RAID5 array. Art S. Kagel > Andrew Hamm wrote: >> >> Mark D. Stock wrote: >> > >> > I would like to see at least three on any system, especially one making >> > heavy use of temp tables. Preferably on different disks. Although that may >> > be difficult with your striping. >> >> And anyway, striping is the enemy of performance on standard Intel systems in >> these days of multi-multi-GB disks. It overloads the disk with too many >> active access threads, which reduces performance to the minimum the disk can >> offer instead of the maximum it can offer. That's typically a factor of about >> 4:1. > > I now for a while testing on an Intel box with two 3-ware HW RAID controllers > on 2 PCI busses 64bit/66MHz 1 RAID-5 with 4 parallel 160 GB IDE disks 1 RAID > 10 with 4 parallel 160 GB IDE disks > > Running 6 bonnie++ tests in parallel shows me better read perf from RAID5. > Ratio RAID 10 : RAID 5 is like 2:3 > (reads from 3 instead of 2 disks at any given time, so it makes sense) > > Write performance of the RAID5 just suxx (20 MB/sec). > > bonnie++ random write performance of the RAID10 is over 105MB/sec > > HPL performance on this system beats the heavy $$$$ SANs by a magnitude! (if > NOT loading onto the RAID5): > I can load 80.000 2 KB pages per sec reading from RAID5 loading into 8 chunks > which sit on the RAID10. (Version 9.40.UC2 on SuSE 8.2) I con unload >120.000 > pg/sec from the RAID5 and 81.000 from RAID10 > > Parallism of more than 8 HPL threads tends to increase the overall loading > duration, whereas 7 parallel HPL threads is not as fast as 8. > > 8-way parallel on this 4 disk RAID10 is the sweet spot for writes, so it > seems. > > dic_k