thank you for your instant reply.
1. so far,we haven't used cache yet.
2. about the version:
qemu--QEMU emulator version 1.4.0 (Debian 1.4.0+dfsg-1expubuntu4)
ceph---ceph version 0.61.4
the xml file of the vm is as belows:
<domain type='kvm' id='4'>
<name>i-2-49-VM</name>
<uuid>126085aa-8b39-3a04-a9d4-737a4f82a8b4</uuid>
<description>CentOS 5.5 (64-bit)</description>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>1</vcpu>
<cputune>
<shares>1000</shares>
</cputune>
<os>
<type arch='x86_64' machine='pc-i440fx-1.4'>hvm</type>
<boot dev='cdrom'/>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/usr/bin/kvm-spice</emulator>
<disk type='network' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<auth username='admin'>
<secret type='ceph' uuid='17311be9-bd3c-33cd-aaa0-6b2fe27908e4'/>
</auth>
<source protocol='rbd' name='cloudstack-2/4c6044a6-ab8c-4f6a-a33c-2a68be73ef6b'>
<host name='XXXXXXXXXX' port='6789'/>
</source>
<target dev='vda' bus='virtio'/>
<alias name='virtio-disk0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
</disk>
<disk type='network' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<auth username='admin'>
<secret type='ceph' uuid='17311be9-bd3c-33cd-aaa0-6b2fe27908e4'/>
</auth>
<source protocol='rbd' name='cloudstack-2/9a818d53-de09-4347-9d87-7823697cc12b'>
<host name='XXXXXXXXXX' port='6789'/>
</source>
<target dev='vdb' bus='virtio'/>
<alias name='virtio-disk1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw' cache='none'/>
<target dev='hdc' bus='ide'/>
<readonly/>
<alias name='ide0-1-0'/>
<address type='drive' controller='0' bus='1' target='0' unit='0'/>
</disk>
<controller type='usb' index='0'>
<alias name='usb0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
</controller>
<controller type='ide' index='0'>
<alias name='ide0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<interface type='bridge'>
<mac address='06:ff:28:00:00:0b'/>
<source bridge='cloudbr0'/>
<target dev='vnet9'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/4'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/4'>
<source path='/dev/pts/4'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
<input type='tablet' bus='usb'>
<alias name='input0'/>
</input>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='5903' autoport='yes' listen='0.0.0.0'>
<listen type='address' address='0.0.0.0'/>
</graphics>
<video>
<model type='cirrus' vram='9216' heads='1'/>
<alias name='video0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
<memballoon model='virtio'>
<alias name='balloon0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</memballoon>
</devices>
<seclabel type='none'/>
</domain>
Best regards.
在 2013-06-28 15:54:07，"Alex Bligh" <alex@xxxxxxxxxxx> 写道：
>
>On 28 Jun 2013, at 08:41, 华仔 wrote:
>
>> write speed: wget http://remote server ip/2GB.file , we get a write speed at an average speed of 6MB/s.(far behind expected)
>> (we must get something wrong there, we would appreciate a lot if any help comes from you. we think the problems comes from the kvm emulator, but we are not sure, can you give us some advice to improve our vm's disk performance in the aspect of writing speed?)
>
>Are you using cache=writeback on your kvm command line? What about librbd caching? What versions of kvm & ceph?
>
>--
>Alex Bligh
>
>
>
>
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