There is a company (DataCore Software) that has been making / shipping products for many years that I believe would help in this area. I've used them before, they're very solid and have been leveraging the use of commodity server and disk hardware to build massive storage arrays (FC & iSCSI), one of the same things ZFS is working to do. I looked at some of the documentation for this topic of discussion and this is what I found:
CRC/Checksum Error Detection In SANmelody and SANsymphony, enhanced error detection can be provided by enabling Cyclic Redundancy Check (CRC), a form of sophisticated redundancy check. When CRC/Checksum is enabled, the iSCSI driver adds a bit scheme to the iSCSI packet when it is transmitted. The iSCSI driver then verifies the bits in the packet when it is received to ensure data integrity. This error detection method provides a low probability of undetected errors compared to standard error checking performed by TCP/IP. The CRC bits may be added to either Data Digest, Header Digest, or both. DataCore has been really good at implementing all the features of the 'high end' arrays for the 'low end' price point. Dave Richard Elling wrote: > Orvar Korvar wrote: > >> Ive studied all links here. But I want information of the HW raid >> controllers. Not about ZFS, because I have plenty of ZFS information now. >> The closest thing I got was >> www.baarf.org >> >> > > [one of my favorite sites ;-)] > The problem is that there is no such thing as "hardware RAID" there is > only "software RAID." The "HW RAID" controllers are processors > running software and the features of the product are therefore limited by > the software developer and processor capabilities. I goes without saying > that the processors are very limited, compared to the main system CPU > found on modern machines. It also goes without saying that the software > (or firmware, if you prefer) is closed. Good luck cracking that nut. > > >> Where in one article he states that "raid5 never does parity check on >> reads". Ive wrote that to the Linux guys. And also "raid6 guesses when it >> tries to repair some errors with a chance of corrupting more". Thats hard >> facts. >> >> > > The high-end RAID arrays have better, more expensive processors and > a larger feature set. Some even add block-level checksumming, which has > led to some fascinating studies on field failures. But I think it is > safe to > assume that those features will not exist on the low-end systems for some > time. > -- richard > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > > > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
