OK, just joined the list and rad the faq, and something caught my eye. Tiobench results are apparently supposed to INCREASE when there are more threads. What I have is Tiobench results decreasing with more threads. This is my setup: Celeron 633 196 MB PC 133 Adaptec 29160 SCSI controller (PCI) 5 IBM Ultrastar 18XP (18gig, SCSI-3) disks hanging off the Adaptec controller Red Hat 7.3 Linux (2.4.18-3) Experimenting with different RAID configurations, I have found that I can not get more than 32 MB/s from this array with 4 disks, one spare. I have actually found out that the disks set the SCSI bus at 40 MB/s (since the disks are old) and that in RAID 0 it scales well, the speed doubles for two disks, and then the third disk brings in a little more performance, and then things topp off at 32 MB/s with four disks. Adding the fifth disk gains no extra performance. Apparently VIA chipsets have problems with PCI bursting, so that is why I can't see the full 40 MB/s. That's fine. But, my tests with tiobench also show that performance decreases as extra threads are added. I am testing with a file of 800 MB (approx. 4x size of RAM, to get meaningful results) and the decrease with threads, while READING only, is consistent in all RAID levels. The write performance will sometimes increase, sometimes stay the same. WHY is this happening? Is it something I have not set up right , or what? I am not so much interested in getting more speed out of these old disks, they are gonna be replaced soon anyway, but I REALLY want to know WHY is this?? Can anyone give me any pointers? Thanks, Vlad. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
