Re: [Xen-users] tap:aio not working...

["Nick Couchman" <Nick.Couchman@xxxxxxxxx>]

Well, I've actually experienced mixed results with attaching a tap:aio device 
to dom0.  Sometimes it works and sometimes it doesn't, and I'm having trouble 
tracking down a pattern to it.  When it fails in dom0, instead of the error 
message about hotplug scripts not working, I get a "Backend device not found" 
message.  

I'll be moving to SP2 as soon as you release it, but I'm wary of doing that on 
these production machines until it's officially released.  Any other hints on 
what I may be able to look at would be much appreciated.  I've also got a 
support case open on my Novell support contract for this issue.

-Nick

>>> On Mon, May 5, 2008 at  6:12 AM, Kevin Wolf <kwolf@xxxxxxx> wrote: 
> Nick Couchman schrieb:
>> xen02:~ # lsmod | grep -i tap
>> blktap                121604  2 [permanent]
>> xenbus_be               8832  3 netbk,blkbk,blktap
>> xen02:~ # ps -ef | grep blk
>> root      7060     1  0 Apr28 ?        00:00:00 blktapctrl
>> root     31500 31466  0 06:59 pts/0    00:00:00 grep blk
>> 
>> Clearly the blktap module is loaded (is there another one I need??) and the 
> control daemon is running. 
> 
> Looks right so far.
> 
>> The only messages that I get with BLKTAP or TAPDISK occur when I manually do 
> an "xm block-attach" to dom0 to test out the tap:aio method. 
> 
> So if you try to block-attach the image to Dom0 it works and the problem 
> is only with DomU? Unfortunately I currently don't have a machine 
> installed with SP1 here, it's all the SP2 RCs now.
> 
> Looking at my own logfiles I found that I get this "blkback: ring-ref" 
> lines only when I use file. With blktap it doesn't show up at all. So 
> the information that you wanted blktap might have been lost somewhere in 
> the middle of the domain startup. This would also explain the missing 
> BLKTAP and TAPDISK lines.
> 
> Kevin



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