On Wed, Dec 31, 2008 at 12:58 PM, Miles Nordin <car...@ivy.net> wrote:
> >>>>> "db" == Dave Brown <dbr...@csolutions.net> writes: > > db> CRC/Checksum Error Detection In SANmelody and SANsymphony, > db> enhanced error detection can be provided by enabling Cyclic > db> Redundancy Check (CRC) [...] The CRC bits may > db> be added to either Data Digest, Header Digest, or both. > > Thanks for the plug, but that sounds like an iSCSI feature, between > storage controller and client, not between storage controller and > disk. It sounds suspiciously like they're advertising something many > vendors do without bragging, but I'm not sure. Anyway we're talking > about something different: writing to the disk in checksummed packets, > so the storage controller can tell when the disk has silently returned > bad data or another system has written to part of the disk, stuff like > that---checksums to protect data as time passes, not as it travels > through space. > The CRC checking is at least standard on QLogic hardware HBA's. I would imagine most vendors have it in their software stacks as well since it's part of the iSCSI standard. It was more of a corner case for iSCSI to try to say "look, I'm as good as Fibre Channel" than anything else (IMO). Although that opinion may very well be inaccurate :) --Tim
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