Issue with ppc64/vibmscsi

[Anton Blanchard]

Hi Ivan,

> It seems (by my experience) that the pSeries AIX based Virtual I/O Server
> (at release 1.1.1.20) has a limit of 128K (256 sectors) request size when
> performing I/Os over the Virtual SCSI interface (using the SRP/RDMA
> hypervisor based transport).
> 
> The symptom is that some large I/Os will fail the adapter (putting it
> offline).
> 
> The Virtual I/O server indicates an errlog entry of type "37DDE80C"
> (Misbehaved Virtual SCSI Client)
> 
> I couldn't find any documentation on any fixed request size limit anywhere.
> 
> I attempted this, and this circumvents the problem (in my particular case) :
> 
> Set max_sectors=256 to the scsi_host_template in ibmvscsi.c
> 
> Of course, this is a bit .. brutal .. (it would limit the transfer size in
> environments that probably do not need it, such as when talking to an
> iSeries OS/400 or i5/OS partition) - And eventually, the limit in VIOS may
> go away (if, as I suspect, this is an actual problem in the current VIOS
> code).
> 
> So a config statement may be appropriate.. Or maybe just wait for a new VIOS
> release or set pf PTFs..

I agree its an AIX bug. Dave, Santi, does this sound familiar to you? 

Anton