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 > |