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RAID 3/5?

Occasional Visitor

RAID 3/5?

What does "RAID 3/5" mean? My HSG80 uses this terminology, but I can't find an explanation.

My understanding is that RAID 3 is striping with a dedicated parity disk, while RAID 5 is striping with distributed parity. What am I missing?

Leif Halvarsson_2
Honored Contributor

Re: RAID 3/5?

You are correct about RAID 3 and RAID 5. You can read about "RAID Storagesets" in the manual for HSG80 (see page 2-23).

As I can find RAID 3/5 uses distributed parity (and should be a RAID 5). I can't see the difference.
Peter Mattei
Honored Contributor

Re: RAID 3/5?


Both Raid levels stripe over multiple disks. The difference is in the placement of the parity data. R3 has a dedicated parity disk while R5 distibutes parity over all disks.
R3 is optimal for sequential data while R5 is better for random access.
Read more in the attached doc.

I love storage
Vincent Farrugia
Honored Contributor

Re: RAID 3/5?


RAID 3/5 is ONE RAID level. RAID 3 has an excellent data rate but poor request rate, on the other hand, RAID 5 has excellent read performance but moderate write performance.

If the controller is able to handle both parity generation schemes of RAID 3 and RAID 5, and uses them in case of advantage, the combination of them gives better write throughput overall compared to the pure RAID 3 or RAID 5 implementations. It is just the best out of both RAID levels.

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