[sheepdog] [sbd] I/O stuck shortly after starting writes

[Marcin Mirosław]

W dniu 02.06.2014 05:52, Liu Yuan pisze:
[...]

> Actually, this is a notorious memory dead-lock and can't be solved if you run
> sbd and sheep on the same nodes. It is a problem similar to NFS that you have
> NFS server and client in the same machine.
> 
> Deadlock:
> Suppose SBD has dirty pages to writeout to backend of sheep. But sheep itself
> need some clean pages to hold this dirty data before do actually disk IOs and
> wait kernel to clean some dirty pages, unfortunately those dirty pages need
> sheep's help to writeout.
> 
> Solution:
> never run client SBD and sheep daemon on the same node.


Hi!
It's a bad news. So iSCSI welcome back on the board:)
Is it possible to disallow using such configuration in sbd? After such
deadlock my test VDI was always broken. Check returns that all pieces
was missing.

Thanks Liu.
Marcin