• better latency - the access time in the RAID becomes a critical competitive factor for the overall SSD array performence.

• smaller RAM cache (and different sorting algorithms).

Nibble:- RAID and Me

I first came across the concept of RAID in 1986 when I was joined a company called Databasix as their hardware engineering manager. Among the many things on my to-do list was to build a working RAID controller and RAID array demonstration system.

"I don't know much about hard drives" - I said. I could afford to be honest - because these guys had already seen the worst when they first met me. My VC backed networked data acquisition company was going bust and they had been a potential buyer.

"There's not much too it." My boss said. "Just read the manuals that come with the disk drives. We want to see if RAID will give us fast real-time disks at a cost that's significantly less than the video disks from Japan used by our sister company Quantel."

"OK" I said. "I don't know much about RAID either."

"Nobody does. Here's a bunch of articles. They tell you all you need to know. We'd like the demonstration ready in 3 weeks."

"That sounds like a very short time to me."

"We've already ordered the disks to save time. You order whatever chips you need, and use some of the software guys to help on this."

From memory, I think I got the demo deadline pushed out to about 4 to 5 weeks.

We also had an Artificial Intelligence demo being worked on at the same time by about 50 software engineers, and a parallel computing demo, but the RAID functionality was the "must have" thing which could not be easily dropped from the sales plan.

We did build a working 4 drive RAID system. One of our biggest problems had been the high rate of Dead On Arrival disk drives. That caused a lot of problems which we initially blamed on the software. Hard drives were a lot more sensitive in those days and could be killed just by putting them down on your desk.

But by then I knew a lot more about disks and realised that the Inexpensive Disks we used in our demonstrator weren't anywhere near as fast as they could have been, because they were the wrong standard. Then, as now, there were many interface standards for disk drives. If you're going to build a fast system then you might as well use fast building blocks. Dataquest was telling me that we should probably be using SCSI instead.

As my imposed wish lists started to pile up and commercial reality started hitting my new employer, I decided that it would be a heck of lot easier to partner with a disk controller company which was already down this part of the curve, and later we became a beta site for dozens of manufacturers of processor cards, array processors, hardware interfaces, memory and disk drives as we tried to make a business out of selling the technology curve to military buyers almost before it was really there. That was great fun, but a different story.

It was about 10 years after that before RAID systems next appeared in my life - when RAID companies like DEC (acquired by Compaq and now part of HP) and Data General (acquired by EMC) started promoting their RAID systems to readers of my Sun foused SPARC Directory.

Nearly 12 years after my first acquaintance with RAID it became one of the first 4 product categories here on STORAGEsearch.com. And although the interface patterns have changed over the years, from DAS SCSI, then Fibre-channel SAN, then Ethernet NAS, and then iSCSI, the ideas inside the box have remained the same.

When you get to be an old guy like me, it's a lot easier if some of the new stuff which hits your brain, is actually a rehash of old stuff.