Richard W.M. Jones wrote: > On Sun, Oct 30, 2011 at 08:28:30AM +0000, Ken Smith wrote: > >> Hi, I have two virtual machine setups, one is FC13 and the other is >> FC14, using kvm and guests created using the Virtual Machine Manager. >> >> I have noticed that the disk performance is slower than I would have >> expected. Here are some figures >> >> FC14 Host (i7, 8Gb memory, Two 1Tb sata disks in soft Raid0) >> >> Host, 9.76 MBytes/Sec >> Host file system Ext4 formatted on md0, Intel MB >> Centos 5.6 Guest, 6.45 MBytes/Sec >> Virtio, QEMU/RAW, No Specific cache setting >> RedHat 8 Guest, 0.426 Mbytes/Sec >> Correction this is FC8, IDE Device, QEMU/RAW, No Specific cache setting >> >> FC13 Host (i7, 4Gb Memory, One 1Tb sata disk) >> >> Host, 47.6 MBytes/Sec >> Host file system Ext4 formatted LV on partition(s), ASUS MB >> Centos 5.6 Guest, 12.52 MBytes/Sec >> IDE, QEMU/RAW, No Specific cache setting >> RedHat 7.3 Guest, 1.42 MBytes/Sec >> IDE, QEMU/RAW, No Specific cache setting >> FC6 Guest, 16 MBytes/Sec >> IDE, QEMU/RAW, No Specific cache setting >> Centos 6 Guest, 15.72 MBytes/Sec >> Virtio, QEMU/RAW, No Specific cache setting >> The tests were run by copying large files (650 Mbytes) and timing the >> result. >> >> I didn't expect the legacy 2.4 kernel guests to perform so slowly. >> >> The performance of the soft raid0 host machine is disappointing. >> >> On the FC13 host, without Raid, the guest performance at 1/3 of the host >> is also a surprise. >> >> What experience and guidance is out there on this area? >> > There's not enough information in this post to say > what is going on. > > What device are you exporting to the guest? virtio? IDE? > > What are you using on the host to store the disks? qcow2? raw file? > sparse or not? an LV? a partition? > > What precise settings for cache etc are being used? Use 'virsh > dumpxml' and look at the<disk> section. > > Also you should try a later host. Some performance improvements have > been made in more recent versions of qemu, and in any case F14 is > almost out of support. > > Rich. > > I've pulled most of the information you requested. See above. I don't see any specific cache settings on either machine. Is there somewhere I would see the default setting on the machine? The raw files are the full size of the filesystem they are intended to hold.
Thanks Ken -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ virt mailing list [email protected] https://admin.fedoraproject.org/mailman/listinfo/virt
