Re: Disk I/O stuck with KVM - no clue how to solve that

[Hermann Himmelbauer <dusty@qwer.tk>]

Am Samstag 06 November 2010 20:58:12 schrieb Stefan Hajnoczi:
> On Fri, Nov 5, 2010 at 5:16 PM, Hermann Himmelbauer <dusty@qwer.tk> wrote:
> > I experience strange disk I/O stucks on my Linux Host + Guest with KVM,
> > which make the system (especially the guests) almost unusable. These
> > stucks come periodically, e.g. every 2 to 10 seconds and last between 3
> > and sometimes over 120 seconds, which trigger kernel messages like this
> > (on host and/or guest):
> >
> > INFO: task postgres:2195 blocked for more than 120 seconds
>
> The fact that this happens on the host too suggests there's an issue
> with the host software/hardware and the VM is triggering it but not
> the root cause.
>
> Does dmesg display any other suspicious messages?

No, there's anything that can be seen via dmesg. I at first suspected the 
hardware, too. I can think of the following reasons:

1) Broken SATA cable / Harddisks - I changed some cables, no change, thus this 
is probably ruled out. I also can't see anything via S.M.A.R.T. Moreover, the 
problem is not bound to a specific device, instead it happens on sda - sdd, 
so I doubt it's harddisk related.

2) Broken Power Supply / Insufficient Power - I'd expect either a complete 
crash or some error messages in this case, so I'd rather rule that out.

3) Broken SATA-Controller - I cannot think of any way to check that, but I'd 
also expect some crashes or kernel messages. I flashed the board to the 
latest BIOS version, no change either.

However, it seems no one except me seems to have this problem, so I'll buy a 
new, similar but different mainboard (Intel instead of Asus), hopefully this 
solves the problem.

What do you think, any better idea?

Anyway, thanks for your reply!

Best Regards,
Hermann

-- 
hermann@qwer.tk
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