JBOD over multiple disks

nas102 wrote:
Do you think having multiple JBOD over multiple disks slow down read/write speed and response?

Generally not, though it depends on exactly what you are doing. In the specific case of RAID-1, the impact should be minimal. I run my RN102 in jbod, and I see the same results with NAStester that folks running xraid/raid-1 report.

Writing to a RAID array requires updating two disk sectors (on two different disks) for every write. For sequential writes, that will be slower than writing to a single disk. Random I/O is more complicated, since spreading the writes over different disks can reduce seek time. Still, the extra I/O usually makes it slower than jbod.

Reading from a RAID array is a bit different, since there are no parity block updates. Then spreading the reads over the physical disks can improve throughput. But in practice, sequential disk reads are faster than gigabit ethernet anyway. Random read I/O might be faster with multiple disks.