I'm getting wildly different disk IO performance from two storage devices in a Windows Server 2003 guest. I'm using diskgraf to test and get a max of 8MB/s for both reads and writes of a 64MB file on the system drive, but 101MB/s writes and 250MB/s reads on the second drive. The cache is enabled on both drives with driver name='qemu' cache='writeback'/>. Prior to enabling the cache I was getting just 1.5MB/s reads/writes from the system drive. Both storage devices were created through virt-manager, and are raw image files access from an NFS server (SATA RAID5). Really hoping that someone can give me some pointers for fixing the problem. # modinfo kvm_intel filename: /lib/modules/2.6.18-194.32.1.el5/weak-updates/kmod-kvm/kvm-intel.ko license: GPL author: Qumranet version: kvm-83-164.el5_5.25 srcversion: 8C538112F6F8EC1E834351B depends: kvm vermagic: 2.6.18-194.17.1.el5 SMP mod_unload gcc-4.1 parm: bypass_guest_pf:bool parm: enable_vpid:bool parm: flexpriority_enabled:bool parm: enable_ept:bool parm: emulate_invalid_guest_state:bool # qemu-img info mercury_win2003_exchange2007_64.img image: mercury_win2003_exchange2007_64.img file format: raw virtual size: 29G (31457280000 bytes) disk size: 29G # qemu-img info mercury_win2003_exchange2007_64_disk2.img image: mercury_win2003_exchange2007_64_disk2.img file format: raw virtual size: 20G (20971520000 bytes) disk size: 20G # file mercury_win2003_exchange2007_64.img mercury_win2003_exchange2007_64.img: x86 boot sector, Microsoft Windows XP MBR, Serial 0x1ef01ee; partition 1: ID=0x7, active, starthead 1, startsector 63, 61416432 sectors # file mercury_win2003_exchange2007_64_disk2.img mercury_win2003_exchange2007_64_disk2.img: x86 boot sector, Microsoft Windows XP MBR, Serial 0x844035a3; partition 1: ID=0x7, starthead 1, startsector 63, 40949622 sectors, extended partition table (last)\011 Any thoughts/ideas? Thanks, Kevin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
