Hi, I want to know how much performance degrade (if any) is expected when same disks-same config settings are used for RAID0 and RAID6. With the help of few mails on this mailing list and information available on opensource, I tuned my disks/raid with which I got following, Linux kernel used: 2.6.32 RHEL6.4 Underlying scsi devices config set at: max_sectors_kb=8192, scheduler=noop (or deadline) Buffered IO using xdd, dd:: block size=4MB, all sequential writes IO done directly on md/raid device /dev/mdX 6 disks buffered IO total write speed = 1000 MBps i.e. around 165 MBps per disk RAID0: 64KB chunk size 6 disks = 980 MBps i.e. around 164 MBps per disk RAID6: 64KB chunk size 6 (4 + 2) disks with stripe_cache_size = 8192, preread_bypass_threshold = 8192. No pre-reads seen. Gives 340 MBps i.e. around 85 MBps per data disks (4) i.e. around 45-50% drop is seen. Same IO tool and IO settings used for all 3 experiments. In general, Is this much drop expected with RAID6 against same RAID 0 config? If not, Is any configuration setting is missing? If I could drive RAID0 with line speed should I expect same with RAID6 also. Thanks in advance, Mandar Joshi -- 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
