Re: [Xen-API] XCP Storage resiliency

[Nathan March <nathan@xxxxxx>]

On 6/17/2013 4:47 PM, Nathan March wrote:
> Hi,
>
> Have been playing around with XCP and I'm looking to achieve high 
> resiliency in the situation of a backend NFS SR failure. I've got an 
> existing cluster based around xen open source and I've successfully 
> tested NFS outages of as long as 1 hour, during which IO/VMs simply 
> hang and upon recovery typically come back gracefully.
> Unfortunately when I try pulling access from an xcp host, it pretty 
> quickly (within a minute or two) starts returning I/O errors:
> [871449.552331] end_request: I/O error, dev tda, sector 26384232
> [871457.632417] end_request: I/O error, dev tda, sector 19276360
>
> Likewise in the VM I'm seeing I/O errors being returned:
>
> [ 4657.253261] end_request: I/O error, dev xvda, sector 19276432
> [ 4657.253264] Buffer I/O error on device xvda4, logical block 50002
> [ 4657.253268] lost page write due to I/O error on xvda4
> [ 4657.253275] end_request: I/O error, dev xvda, sector 19276440
> [ 4657.253283] end_request: I/O error, dev xvda, sector 19276448
>
> I've tried mounting the NFS SR with -o hard instead of the default 
> soft but it seemed to have no significant impact.
> Is what I'm looking to do possible with XCP? I'd simply like the vms 
> to hang while waiting for IO or optionally have the HV pause them (I 
> think vmware does this). Googling has failed me so any useful tips 
> would be appreciated, thanks!
> - Nathan
Hi,

Revisiting an old thread here in the hope that some fresh eyes see it 
and might have some insight? Frustrating thing is that this isn't a 
problem with windows VMs and only appears to happen on Linux, usually 
it's the other way around =)
Also have a thead going for this on the citrix forums where another user 
is also trying to resolve this, I've got quite a few more details posted 
in here now: http://forums.citrix.com/thread.jspa?threadID=335505
- Nathan


--
Nathan March<nathan@xxxxxx>
Gossamer Threads Inc. http://www.gossamer-threads.com/
Tel: (604) 687-5804 Fax: (604) 687-5806


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