On Nov 8, 2007, at 1:38 PM, Brandorr wrote: > Some of my Linux friends are getting into ATA over Ethernet... Is this > an area anyone is investigating in Solaris? (More of a curiosity than > anything else) > >> > From my observation, iSCSI is "poor man's" FChannel. It seems that AoE > is "poor man's" iSCSI. http://en.wikipedia.org/wiki/ATA_over_Ethernet
iSCSI might be a "poor man's" FC, as you put it, but arguably AoE is certainly not a poor man's iSCSI. It's just "poor". To put it in a nicer tone, it's really not all that compelling of an investment. My impressions; 1) iSCSI target servers and initiators already come for free (included with several OSes, including Solaris), whereas AoE requires a dedicated physical NIC or (optimistic guess) tagged VLAN to operate, not to mention arrays that so far appear to be made by only one company (Coraid). There's the software target servers for Linux, but that stuff appears to currently be alpha quality... not something I'd run business on. So cheaper than iSCSI? I don't believe that. 2) Unlike both FC and iSCSI, there is no concept of reliable delivery of data frames or congestion control on AoE. AoE initiators and targets appear to just poop stuff onto the wire as fast as they can and hope for the best. 3) MPIO is not described in any AoE spec that I've read, so the robustness and standardization of ANSI T10-based multipathing isn't there with the OS integration it brings with it (eg: MPxIO on Solaris). 802.3ad NIC teaming could get you kind of there but with that you're still limited to connecting to the same (one) switch so you're not protected against a whole switch failing or going offline as you would be with FC or iSCSI (via MPIP in Solaris) 4) There doesn't appear to be any standards house (ANSI, IETF, etc) in control of the AoE spec as it is[1]. The authors have done a good job putting it in a convincing IETF RFC format, but it's still completely a internal spec to Coraid. I checked IETF's site and there doesn't appear to even be a draft proposal for a AoE standardization tract. So I think more than anything else, AoE is more of a novelty technology. It got lucky with some press in Linux rags and, like many Linux users, overlooked its mediocrity because it is marketed as cheap. Yeah, cool, it's storage over raw ethernet, but its touted simplicity comes at a cost of features and abilities that FC and iSCSI networks have enjoyed for a long time. /dale [1] http://www.coraid.com/documents/AoEr10.txt _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss
