[Sheepdog] sheepdog image created but sheperd does not show it

[Piavlo]

Hi,
 
MORITA Kazutaka wrote:
> Yes. Sheepdog uses a hash function to map nodes to a consistent hash
> ring, so if the number of nodes is small, objects are not well
> distributed. 
 If there are say 10 storage nodes , most prople would probably want to 
use --copies=2 or --copies=3
not --copies=10. Since single VM  image is distributed among all 10
nodes with --copies=2 - it is enough for
two nodes out of 10 to go offline and the VM won't be available anymore.
If one storage node goes offline - does sheepdog automatically
replicates the data object that the failed node had to other nodes
so that  there are always exactly --copies= of each sheepdog object in
the active set of storage nodes?
> I think sheepdog should take different approach to map
> nodes to the ring for better balancing.
>   
Maybe some ideas from elliptic network can be implemented.
It seems for me like a good idea just to take the elliptics project asis
and integrate it with kvm.
> Each disk image is divided into 4 MB objects, and lower 18 bits in the
> file name (block number) is a index of the objects.
>
> In your case,
>  - first 4 MB (0 ~ 4 MB) is allocated as the object 40001
>  - the next 4 MB (4 MB ~ 8 MB) is not allocated
>   
So why exactly these next 4MB are not allocated?
>  - the next 4 MB (8 MB ~ 12 MB) is allocated as the object 40003
>  - the next 4 MB (12 MB ~ 16 MB) is allocated as the object 40004
>  - ...
>   (40000 is a vdi object, and contains metadata for the VM)
>   
I'll test 7) & 8) more thoroughly and get back to you with the results.

Thanks
Alex

>> 7) After I created several images and stop sheepdog all nodes and
>> started them later again, all VMs can be listed but then I try to create
>> another image I get
>>
>> shell-srv1> kvm-img convert -f raw -O sheepdog /dev/sys/kvm-img foo
>> find_vdi_name 1041: Invalid error code, foo
>> find_vdi_name 1041: Invalid error code, foo
>> qemu-img: Could not open 'foo'
>> sheel-srv1>
>>     
>
> Sorry, I couldn't reproduce the problem. Please confirm that applying
> the patch and running make on all three nodes. If the problem is not
> resolved, would you send me collie logs in /var/log/syslog?
>
>   
>> 8) Started a VM with sheepdog image but it gets stuck during the boot
>> process:
>>
>>     
>
> I couldn't reproduce this, too. What happens if you use only one node
> or --copies=3 option?
>
> Thanks,
>
> MORITA, Kazutaka
>