On Wednesday 06 December 2006 17:42, Jeremy Linton wrote:
> On Wednesday 06 December 2006 16:50, Mike Christie wrote:
> > > For iscsi, we could negotiate a value like MaxBurstLength which says
> > > don't send commands with a payload larger than that size. I would guess
> > > other transports have something similar. We have to check or make sure
>
> ...
>
> > Oh yeah the exception I am thinking about may not be max sectors exactly
> > but something close like iscsi's MaxBurstLength limit. Maybe iscsi LLDs
> > are supposed to be translating that iscsi limit to max_sectors in which
> > case we are talking about the same thing. For this limit we do not want
>
> Sort of off topic, but the iSCSI MaxBurstLength doesn't set the max
> transfer size, it simply is the amount of data that can be sent without a
> R2T. If the transfer is larger then you have to wait for the R2T. In
> practice it ends up controlling the _minimum_ amount of buffer space that
> needs to be available _before_ the transfer starts, otherwise performace
> sucks.
Whops, Slight clarification, the MaxBurstLength is the max sent between
R2T's
what I described above is closer to the FirstBurstLength. What you guys are
describing might better be the MaxRecvDataSegmentLength, but not really since
that parameter should be hidden within the iSCSI driver.
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