Hi, all We are about to test the performance with FC-SAN Currently there are 15 Hypervisors connected to a 16T LUN with 4G fiber channel. LVM is used to manage the VM''s disks, VM''s disk image is created as logic volume over the LUN. All VMs are HVM. when dd the lv from dom0, the performance is acceptable, range from 150 ~ 300MB/s but when dd the local disk in guestOS (centOS 5.5 domU), the peformance is poor, about 40MB/s my question is, is this normal? if not, any clues for performance tuning? Thanks & Regards _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jan-Aage Frydenbø-Bruvoll
2011-Apr-19 08:35 UTC
Re: [Xen-users] LVM over FC-San poor performance
Hi, On Tue, Apr 19, 2011 at 09:26, Mice <mice1982@gmail.com> wrote:> > Hi, all > > We are about to test the performance with FC-SAN > Currently there are 15 Hypervisors connected to a 16T LUN with 4G fiber channel. > LVM is used to manage the VM''s disks, VM''s disk image is created as logic volume over the LUN. > All VMs are HVM. > > when dd the lv from dom0, the performance is acceptable, range from 150 ~ 300MB/s > but when dd the local disk in guestOS (centOS 5.5 domU), the peformance is poor, about 40MB/s > > my question is, is this normal? if not, any clues for performance tuning?For what it''s worth, I am struggling with a structurally similar problem, although the underlying infrastructure is different. I have a Nexenta storage server with COMSTAR iscsi set up - the performance is acceptable from the dom0s (the network infrastructure becomes the limiting factor before the server starts struggling), but as soon as I benchmark the (paravirtualised) VM disks, I get similar numbers to what you outline in your posting. I am quite keen to find the source and a solution to this - if there is anything I can contribute with along the way, please let me know. Best regards Jan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tue, Apr 19, 2011 at 3:26 PM, Mice <mice1982@gmail.com> wrote:> All VMs are HVM.> > when dd the lv from dom0, the performance is acceptable, range from 150 ~ > 300MB/s > but when dd the local disk in guestOS (centOS 5.5 domU), the peformance is > poor, about 40MB/s > > my question is, is this normal? if not, any clues for performance tuning?AFAIK it is. That''s the consequence of using HVM. I suggest you try with PV domU and see how it goes. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users