[fedora-virt] Thoughts on storage infrastructure for small scale HA virtual machine deployments

[Ask Bjørn Hansen]

On Mar 1, 2010, at 18:56, Dennis J. wrote:

> The question that bugs me is how I can get enough bandwidth between the 
> hosts and the storage to provide the VMs with reasonable I/O performance.
> If all the 40 VMs start copying files at the same time that would mean that 
> the bandwidth share for each VM would be tiny.

It really depends on the specific workloads.  In my experience it's generally the number of IOs per second rather than the bandwidth that's the limiting factor.

We have a bunch of 4-disk boxes with md raid10 and we generally run out of disk IO before we run out of memory (~24-48GB) or CPU (dual quad core 2.26GHz or some such).

If your storage boxes have lots of disks, BBU backed raid controllers and say 4 ethernet interfaces then the performance might be better than using local disks.   Of course quickly then it's not that cheap anymore.  :-)


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