Many Raid1 vs a Raid10
I have a big server, Quad Opteron with 11GB Ram, 1TB storage over 40 SCSI 10k rpm disks. The server is running Oracle on Linux and I want to know which setup would be faster, having the datafiles spread out over 20 Raid 1 arrays or on a single Raid 10 array?
The key words are Random Access since it does largely simultaneous random reads.
There is an argument that it's faster to have all the separate raid 1s since there is less contention on each spindle and hence less seek time. When dealing with multiple requests it's likely that the request will be answered by separate disks which should allow for faster simultaneous responses.
I know raid 5 is too slow and raid 0 is fast, but we need redundancy, so these 2 are not options.
Does anybody know the deep magic behind this stuff, how do 20 Raid 1s compare to a 40 disk Raid10?
i think you answered your own question -
having a big raid 10 is a bad idea because you lose the efficiency from parallel reads. if your data is truly random access, id say keep it in raid 1's.
RAID 10 provides better fault tolerance and rebuild performance than RAID 01. Both array types provide very good to excellent overall performance by combining the speed of RAID 0 with the redundancy of RAID 1 without requiring parity calculations.