Piavlo wrote: > Hi, > > PCextreme B.V. - Wido den Hollander wrote: > >> Hi, >> >> I have been following sheepdog's mailinglist ever since i saw a newspost >> on www.linux-kvm.com, but what kept me wondering was the performance. >> >> > I have not done any performance testing yet, mainly since the sheepdog > patched kvm does not work for me. > So currently I can only test image creation performance. > > But if disk performance is important for you probably need to separate > the host running the KVM VMs completely > from the VMs image storage device (like done with iSCSI or AOE but not > DRBD) since otherwise the KVM host will probably be throttled > by random disk access generated by your VMs (unless you have just a few > VMs) plus occasional overhead while new images are being created. > > AFAIU with current sheepdog implementation the KVM host MUST be part of > the sheepdog storage cluster. > So it would be nice if sheepdog client and sheepdog server could be run > on different hosts - currently one can overcome this > limitation by keeping the btrfs system not on local disk but on > iSCSI/AOE or any other SAN device. > But addition of another SAN technology complicates the overall solution > and reduces stability. > On a second thought using using KVM host as iSCSI initiator for underlying btrfs device, while the iSCSI target is exported from properly tuned ZFS for the workload on Opensolaris on a host with a lots of RAM would probably give you much better performance than a separated sheepdog server on the same host instead of Opensolaris with ZFS. > So if sheepdog could do the job alone it would be much better. > >> At the moment i don't have 3 servers with SMX/VMX to spare for testing >> sheepdog, so i haven't been able to test sheepdog jet. >> >> At the company i work we use a lot of KVM, our redundant storage is >> build on top of iSCSI and DRBD. The performance is great (IOps), so >> that's not an issue, but the waste of hardware is (Master/Slave setup). >> >> >> > AFAIU you have combined iSCSI with DRBD , thus the Master/Slave comes > from DRBD. > With sheepdog you still have hardware overhead since you need to run at > least two sheepdog > server hosts - which for performance reasons should be separated from > the sheepdog clients (the KVM hosts). > > Alex > >> The question that kept me busy was, how is the performance of sheepdog? >> Yes, i understand that sheepdog and btrfs are still under heavy >> development, but in this stage, how is it performing? >> >> Since sheepdog really seems THE solution for building a real cloud with >> KVM. >> >> I'll keep following sheepdog closely and try to set-up a test >> envirioment asap! >> >> >> > > |