Striped Mirrors and Mirrored Stripes?

[DaMiBu]

When HP say that a SmartArray 6i or a 6402 controller support RAID1+0 do them mean "Striped Mirrors" or "Mirrored Stripes".

I ask as most people confuse the definitions of RAID 0+1, RAID 1+0 and RAID 10.

In HP's documentation and spec sheets for a 6402 controller they say "RAID1+0 (Striped, Mirrored)" whereas I would expect them to describe this as "Mirrored, Striped".

With older Smart Array controller I seem to remember them always referring to this RAID as RAID 0+1. Did this change from the 5x to 6x controllers? Does anyone know the history? I am also interested in the controllers in a MSA1000 and MSA1500, are these RAID 1+0 or RAID 0+1 and if RAID1+0 are they really RAID 1+0?!!!! I know what the GUI says when you create them but want to confirm that they are what they should be? (i.e. “Striped Mirrors”)?

Anyone know?

[Marek Nelec]

It is "Striped Mirrors". People that write specs and technology briefs at HP sometime seem to write confusing things. Look at this document:
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00386950/c00386950.pdf
On page 3 it says: "RAID 1+0 is implemented as a striped array of mirrored drives. It is best suited for sites that need high performance and maximum reliability, but are willing to forgo storage efficiency. RAID 1+0 can withstand the failure of half the drives as long as no two drives in a mirrored pair fail; however, it sacrifices storage efficiency."

Although the picture for RAID 1+0 in table one might be a little confusing, because drive pairs 1&3 and 2&4 are mirrored and THEN striped.

[DaMiBu]

Thank you. This is what I wanted to hear.

Do you know what the deal is with 5x array controllers?

PS: attached is a what the tech specification for the 6402 say. As you can see it is wrong!

[Marek Nelec]

Yes, the specification for RAID 1+0 for SA-6402 is contradictory. As for the SA-5x controllers they definitely use RAID 1+0 (even if they referred to it as RAID 0+1).