On Sep 5, 2009, at 9:21 PM, Tracy Reed wrote: > Given that just one ethernet link can easily transport 100MB/s and a > typical SATA hard drive can only do 70MB/s how is the ethernet a > bottleneck? And I use LACP to bond together 2. So I have 2.5 hard > drives worth of bandwidth. But that's just raw throughput. We all know > that the seeks are what usually slow you down. Each of my AoE servers > have 2G of RAM in them for caching.
The raw-bandwidth capacity of SATA-II is 3Gbps, or about 300MB/s. Even if I concede 50% overhead on that, that's still greater than the capacity of a single GigE. Add to that the fact that most enterprise storage is taking advantage of some sort of parallelization via RAID arrays, and you can get even more performance out of the array which simply can't be squeezed into the Ethernet bottleneck. Which is why SANs (from my experience anyway) tend towards FibreChannel (either 2Gbps or 4Gbps) or multiple Ethernet connections bonded together via 802.3ad/LACP/etc. protocols (like you're doing). But a single ethernet channel is *definitely* a bottleneck for most disk access.... Cheers, D _______________________________________________ Tech mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
