[ENBD] Doubled requests

[Arne Wiebalck]

hi peter,

in my setup I observed that from time to time there are more requests
received by the resource than written by the application to the enbd
device.

for instance, if I write 1000 1k blocks to the enbd device on the client
side, the server resource sees 1001 or 1002 requests. I think these
additional requests are triggered by a timeout somewhere inside enbd.
why else should a request be done twice? someone thinks the request has
failed and retransmits/reissues it, but it has already been successful!
there is no wrong data, but some requests are simply carried out multiple
times.

this is of course no problem for a standard setup, since one doesn't care
whether data is written once or multiple times. my resource however does
an XOR with the data already on the resource, and with multiple writes of
the same data I have a problem then, because the effect is zero in this
case ...

do you know what/who could trigger the additional requests/writes? and in
the best case: is there a way to avoid them, by increasing timeouts, for
instance?


thanks,
 arne


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 Arne Wiebalck                        Kirchhoff Institute for Physics
                                           Technical Computer Science
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 e-mail: wiebalck at kip.uni-heidelberg.de
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