Moving beyond RAID and XRAID2

jelockwood wrote:

sphardy wrote: jelockwood wrote: There are now newer more advanced schemes for protecting data compared to the original RAID schemes and I am not just referring to using more redundant drives. Such as? The third article I linked to talks about this. I don't claim to be an expert on that technology but it is clear to even normal people that RAID is not able to cope with the size of modern drives. I suppose in theory if speed had increased at the same rate as capacity has so that the time to rebuild had not grown then that would have prevented the problem. Unfortunately the speed of traditional hard disks has not grown fast enough and as a result the time to rebuild is now a danger.

RAID-5 and RAID-6 are forms of dispersal, with the RAID stripes spreading the data across multiple spindles. Of course in a large data center, you have have an enormous number of spindles, and RAID-5 and RAID-6 don't really take full advantage of that. The main idea in using more modern FEC codebooks is that they allow dispersal over a massive number of spindles.

I agree that rebuild time is an issue already, and will become worse as drive capacities increase. Another trend you didn't mention is power management. There is interest in building arrays of disks that don't require them all to be spinning to access any of the data.

So I'd agree that over time it is inevitable that the RAID formats used in data centers will continue to advance in ways that will take full advantage of the massive amount of spindles that all data centers have.

However, I don't see the applicability of these techniques to consumer storage. I think the key issue here is that 4-6 spindles really is about the most you want to put in a home NAS - so the massive dispersal idea really doesn't apply. SSDs could change the game if they become cheap enough, as they run a lot cooler and don't have the vibrational issues of hard drives.