On 09/17/2013 11:40 AM, Tanstaafl wrote: > On 2013-09-17 11:18 AM, Michael Orlitzky <mich...@orlitzky.com> wrote: >> Any controller that claims RAID10 on a server with 6 drive bays should >> be able to put all six drives in an array. But you'll get a three-way >> stripe (better performance) instead of a three-way mirror (better fault >> tolerance). >> >> So, >> >> A B C >> A B C >> >> and not, >> >> A B >> A B >> A B >> >> The former gives you more space but slightly less fault tolerance than >> four drives with a hot spare. > > Sorry, don't understand what you're saying. > > Are you talking about the difference between RAID1+0 and RAID0+1?
Nope. Both of my examples above are stripes of mirrors, i.e. 1 + 0. > If not, then please point to *authoritative* docs on what you mean. http://www.snia.org/tech_activities/standards/curr_standards/ddf > Googling on just RAID10 doesn't confuse the issues like you seem to be > doing (probably my ignorance though)... > It's not my fault, the standard confuses the issue =) Controllers that can do multi-mirroring are next to nonexistent, so produce few Google results. You can generally assume that RAID10 with 6 drives is going to give you, A B C A B C so you don't get much more fault tolerance by throwing more drives at it. The controller in Grant's server can do this, I'm sure. For maximum fault tolerance, what you really want is, A B A B A B but, like I said, it's hard to find in hardware. The standard I linked to calls both of these "RAID10", thus the confusion. I forget why I even brought it up. I think it was in order to argue that 4 drives w/ spare is more tolerant that 6 drives in RAID10. To make that argument, we need to be clear about what "RAID10" means.
