Re: Re: Xen breaking iSCSI

[Niraj Tolia <ntolia@gmail.com>]

On Mon, 09 Aug 2004 15:14:56 +0100, Keir Fraser
<keir.fraser@cl.cam.ac.uk> wrote:
> 
> Well, I guess it sounds like a merging problem, so it could be that or
> a bug in the backend driver that crept in while merging with the 2.6
> driver.
> 
> We'll need to be able to reproduce it ourselves, or get more
> information by other means. e.g., see if you can track down the bug by
> addign tracing to the drivers, or try a repository from a week or two
> ago and see if it has the same problem.
> 

Traced the bug down to a single changeset. It occurs with this
changeset and after but not before it. I should note that I am using a
xen0 kernel in dom.

ChangeSet@1.1108.17.1, 2004-07-26 16:09:53+01:00, kaf24@scramble.cl.cam.ac.uk
  A better fix for blkdev request merging. Should work for both IDE and
  SCSI, and do as much merging as possible, and also no need for PIO
  fallback mode. 

Let me know if you need any other information.

Thanks,
Niraj

>  -- Keir
> 
> 
> 
> > Since sending the below email, I started looking at the actual iSCSI
> > packets with Ethereal. For a read only experiment, it turns out the
> > disconnect only happens when dom1 requests a read of 16 KB or higher.
> > 4 KB read requests go through just fine.
> >
> > If only dom0 is performing the reads (with no other domain started),
> > the request length is irrelevant and all reads will complete
> > successfully without disconnection.
> >
> > Any ideas?
> >
> > Niraj
> >
> >
> > On Mon, 9 Aug 2004 14:00:34 +0100, Niraj Tolia <ntolia@gmail.com> wrote:
> > > I am trying to run an iSCSI initiator in dom0 and use the device in
> > > dom1. The initiator in question is the Cisco one (3.4.3). For some
> > > reason, running the initiator within Xen causes it to repeatedly
> > > disconnect from Target when one tries to read data from the iSCSI disk
> > > in dom1.
> > >
> > > I used two different targets to make sure it was an initiator side
> > > problem. Also, running the initiator with vanilla linux or even just
> > > dom0 causes no problem. Using a hardware initiator (Intel Pro 1000/T)
> > > causes no problems either.
> > >
> > > Any idea what the reason could be? This used to work earlier  and
> > > definitely before the s/g changes were merged in. Could this be the
> > > cause?
> > >
> > > Niraj
> > >
> >
> > 
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> 
>


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