[gpfsug-discuss] NSD network checksums (nsdCksumTraditional)

Bryan Banister bbanister at jumptrading.com
Tue Oct 30 22:52:35 GMT 2018


Valdis will also recall how much "fun" we had with network related corruption due to what we surmised was a TCP offload engine FW defect in a certain 10GbE HCA.  Only happened sporadically every few weeks... what a nightmare that was!!
-B

-----Original Message-----
From: gpfsug-discuss-bounces at spectrumscale.org <gpfsug-discuss-bounces at spectrumscale.org> On Behalf Of valdis.kletnieks at vt.edu
Sent: Tuesday, October 30, 2018 5:14 PM
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] NSD network checksums (nsdCksumTraditional)

[EXTERNAL EMAIL]

On Tue, 30 Oct 2018 09:03:06 -0000, Jonathan Buzzard said:

> Noting that on a TCP/IP network anything passing over a TCP connection
> is checksummed at the network layer. Consequently any addition
> checksumming is basically superfluous.

Note that the TCP checksum is relatively weak, and designed in a day when a 56K leased line was a high-speed long-haul link and 10mbit ethernet was the fastest thing on the planet.  When 10 megabytes was a large transfer, it was a reasonable amount of protection. But when you get into moving petabytes of data around, the chances of an undetected error starts getting significant.

Pop quiz time:   When was the last time you (the reader) checked your
network statistics to see what your bit error rate was?

Do you even have the ability to do so?

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