I did a few tests of raid10 on an old 3ware 7506-8 today (using 6 drives), both with the built-in raid 10 and md's n2 and chunk sizes from 64KB to 1024KB. - caches dropped before each test - averages of three runs - arrays in synced state - dd tests: 6GB (3MB bs) dd-reads: single drive: 64 MB/s 3w: 104-114 MB/s md: 113-115 MB/s bonnie++-reads: single drive: 36 MB/s 3w: 94-97 MB/s md: 101-108 MB/s The card unfortunately is in a regular PCI slot, not bad considering. dd-writes: single drive: 67 MB/s 3w: 42 MB/s md: 42 MB/s bonnie++-writes: single drive: 36 MB/s 3w: 40-41 MB/s md: 41 MB/s 3w and md speed are pretty much identical and just barely over that of a single drive. If it's because md has to send the same data to multiple disks 3w should have an advantage but it does not. So I ran the same tests using a md-raid5 over the same disks just for kicks (512KB chunks, no bitmap): dd-reads: 115 MB/s bonnie++-reads: 87 MB/s dd-writes: 69 MB/s bonnie++-writes: 62 MB/s Writes are actually a lot better than any raid10 ... despite all the hype it gets on the list. I wanted to go with raid10 for this box because it's not mostly-read for a change. Explanations welcome. Chris -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
