Hi, I've made several tests of RAID 0 performance for upcoming server upgrade, and got strange results. So I ask some experieced users for opinion and suggestions. I've used IBM x3400 with 4 SATA 250GB disks, software RAID and hdparm -tT for test on OpenSUSE 11.0 x64. 1) one disk shows about 60 MB/s, and that's OK 2) two disks in RAID 0 shows about 120 MB/s and that's OK, too 3) three disks in RAID 0 show about 180 MB/s and that's OK, too, but 4) four disks in RAID 0 show 180 MB/s again, and that I can't explain, 5) I tried also nested RAID 0 of two 2-disks RAID 0, which also shows not more that 180 MB/s. I checked mdadm syntax several times (so I can be pretty sure that there is no problem), tried to use several combinations, but I never get more than 180 MB/s, which is far for approx. upper limit 240 MB/s that I expected and wanted. Why I can't see any improvemet by adding fourth disk to RAID 0? Is there any other SW/HW limit that can apply? I tried built-in hardware RAID 0 on all 4 disks. hdparm -tT shows something betwen 90-130 MB/s, what is even more strange. I saw several benchmarks on the Web which cleary shows 240 MB/s in similar configuration like mine. Is hdparm good enough for testing? Is there some proven better benchmark test that somebody can suggest? I have only 4 disks now, so I can't test RAID 50. Thaks for any opinion and suggestion. -- Ivan Guštin