Re: RAID-7 - What is the data organization?

"Charles A. Dellacona" <charlie@dddv.com> writes: >Michael E Willett wrote: >> >> lindahl@deshaw.com (Greg Lindahl) writes: >> >> >In article <327A15D4.1DA5@dddv.com>, >> >Charles A. Dellacona <cdellaco@chester.dddv.com> wrote: >> >> >>In my reading RAID-7 appears occasionally. I am trying to figure out >> >>what it is, most of the internet info is very sales oriented. I want a >> >>little more depth. >> >> >RAID-7 is a marketing slogan, not a real raid level. >> >> >It is apparently like RAID-4 with some caches. >> >> >Given the obnoxious Usenet posting philosophy of the company that >> >sells RAID 7, I would advise not doing business with them. >> >> >Given your requirements (2 GB of data generated each week, store it >> >for a year), I would recommend that you pursue solutions which are >> >flexible, i.e. raid devices which allow you to have many separate 16 >> >gigabyte RAID volumes. Some RAID hardware (like the before-mentioned >> >RAID7 product) only allow you to have one volume. If you will be using >> >a database product on this device, it is also often a good idea to be >> >able to create a small mirrored set of disks to hold your transaction >> >logs. >> >> >-- g >> >> Hi Greg, we appreciate your enthusiasm for that particular RAID >> product you're involved with, but let's not get carried away >> with your "attack ads" -- even though it's November :-) The fact >> of the matter is that the May issue of Business Week reported that >> the RAID 7 company is the US' 4th fastest growing US publicly held >> company over the past three years, in terms of earnings. RAID 7 >> installations are heavily concentrated in bthe ig databases, whether >> Oracle, Sybase, or Informix. >> >> M Willett >> mwillett@storage.com >> Storage Computer >> Nashua, NH >Wow. I guess I hit a nerve. I didn't realize how pointed my question >was. Mr. Willett, I assume from the above that you are an employee of >Storage Computer Company. I've read the WWW information at >www.storage.com and I didn't find my answer, so I'll ask it here of you. >What is the data organization of RAID-7? I've so far gleaned that it is >a block striping concept, similar to levels 4 and 5. >I also understand that the Storage Computer controller incorporates >extensive caching and an embedded operating system that manages all I/O >asynchronously. These are independent of the storage organization. >Charlie From a data organization perspective, parity may be a dedicated disk or be stored on any number of drives, from 2 drives all the way up to n drives (which may be as high as 48 in our system). The benefit of having only a portion of the drives store parity is that it provides you with 99.7% of the WRITE assistance of having parity on multiple drives, without the READ penalty of having to seek over parity info on every drive. From a performance perspective, having a "cache intensive" system does not buy you real performance. Having a hardware architecture and an embedded OS buys you much greater performance than an extra 64 MB of cache. Schedule a demonstration and see for yourself. Mike Willett mwillett@storage.com Storage Computer Corp. Nashua, NH (603) 880-3005 http://www.storage.com/