At Thu, 4 Aug 2011 09:06:14 +0000, Frank Doege wrote: > > Hi List, > > > At first, this really looks like a great project and I feel also that its > very alive, so I am planning to do a test installation of sheepdog storage > backed > KVM > > I have already read what I could find about this project however there is not > so much documentation out there yet. > > I have a couple of questions, I would appreciate if someone could enlighten > me :-) > > 1. > sheepdog needs at least two storage nodes to work, data is distributed like > in a RAID1 therefore I always need > the double of the capacity I plan to use for kvm guests, is there a Parity > option that works like RAID5 ?
No, and there is no plan to support it now, sorry. But if someone would implement the feature, I'd happily merge it into Sheepdog. > > 2. > Does anyone has some performance numbers, with two nodes and 8HDD SAS Raid5 > dual Gbit network bond > What can I get for an estimated performance ? What is the bottleneck here, > the network or the disks ? I have some numbers in the slides I presented before: http://www.osrg.net/sheepdog/_static/kvmforum2010.pdf The bottleneck was the disk I/O In these tests. However, the results strongly depends on the environment and the workloads, so I'm not sure what the bottleneck would be on your environment. > > 3. > Sheepdog uses the network to connect to the nodes, I guess it balances data > in chunks over all available nodes, in the moment > It stores each chunk on a node and a copy on another node, is this rotated > over all nodes or is each image fixed on two nodes ? Sheepdog uniformly distributes chunks to all over the nodes. > > 4. > As sheepdog uses the network as a transport medium am how high is the > latency, is this an issue in production networks ? If your KVMs do many disk syncs to Sheepdog volumes, the network latency could be a problem. But otherwise, I think Sheepdog performance is good. Thanks, Kazutaka -- sheepdog mailing list [email protected] http://lists.wpkg.org/mailman/listinfo/sheepdog
