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SubjectRe: Linux iSCSI Initiator, OpenSource (fwd) (Re: Gauntlet Set NOW!)
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On Mon, 06 Jan 2003 22:20:46 CST, Oliver Xymoron said:

> What was the underlying error rate and distribution you assumed? I
> figure if it were high enough to get to your 1%, you'd have such high
> retry rates (and resulting throughput loss) that the operator would
> notice his LAN was broken weeks before said transfer completed.

The average ISP wouldn't notice things were broken unless enough magic
smoke escaped to cause a Halon dump.

Consider as evidence the following NANOG presentation:

http://www.nanog.org/mtg-0210/wessels.html

Some *98* percent of all queries at one of the root nameservers over a 24-hour
period were broken in some way. And there wasn't even a DDoS in progress
at the time...

Also, I think Andrew was computing the chances that *SOME* packet in the
100T would be mangled in an undetected fashion, so 99% of the time all 100T
would be OK, but 1% of the time there was some subtle block mangling some
dozens of terabytes into the transfer. Given that the TCP slow-start code
is currently busticated for gigabit and higher (it takes *hours* without a
packet drop to get the window open *all* the way - there's IETF drafts
in process about this), it's quite possible that you'd not notice packet
drops due to error among all the congestion drops kicking the window size
down.....
--
Valdis Kletnieks
Computer Systems Senior Engineer
Virginia Tech
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