On Thu, Jan 7, 2010 at 6:29 PM, Piavlo <piavka at cs.bgu.ac.il> 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. Rebased sheepdog client may work for you. > 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. > So if sheepdog could do the job alone it would be much better. Yes, and we are planning to remove this limitation. >> 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). > I think the most interesting feature of sheepdog is its fully symmetric architecture. Sheepdog requires no configuration about cluster membership or each node role, and I believe this feature leads to easy management in the many nodes environment. Regards, Kazutaka Morita |