Re: kernel errors, timeouts and qemu-img usage

[Zenon Panoussis <oracle@provocation.net>]

On 05/03/2011 01:50 PM, Christoph Raible wrote:

> First I alwas get on  ceph -w following "error":
> "[WRN] message from mon2 was stamped 12.271440s in the future clocks not synchronized"
> But i have synchronized my clocks 1 min befor with the same ntp-server..

But are they really in sync?

> The second error is, that I can't create / start an qemu-image on the ceph-filesystem. 
> I want to start a kvm virtual machine with the virt-manager.
> I create an image with

>   "qemu-img create -f qcow2 Platte-qcow2.img 10G"

> The virtual machine never starts. It hangs on look for the "harddisk" 

The image file has to appear as a block device; I suspect you need
http://ceph.newdream.net/wiki/QEMU-RBD .

I have no clue about the third error; what were you doing when you got it?

The fourth error is a timeout too. The file you are trying to write is 2.4
GiB in size (dd defaults to 512 bytes, so 512*5000000 bytes). Your journal
is only 500 MB and you are replicating the data and you are logging 20 on
the same physical hard drive, so I suspect very serious I/O saturation.

Try bs= together with count= for better dd control and write a much smaller
file. Try disabling hung_task_timeout as the error message suggested. Try
also nice and ionice on dd. The problem might be something unrelated, but
this is a quick way to start figuring what's happening.

Z