About disk cache mode
Write performance improvements on the data store disk drive can be achieved by setting the disk cache mode to none. Riverbed supports qcow2 format for the data store disk. With caching mode set to none, the host page cache is disabled, but the disk write cache is enabled for the guest. In this mode, the write performance in the guest is optimal because write operations bypass the host page cache and go directly to the disk write cache. If the disk write cache is battery-backed, or if the applications or storage stack in the guest transfer data properly (either through fsync operations or file system barriers), then data integrity can be ensured.
Open the domain.xml file created during the SteelHead-v for KVM instantiation. Append these attributes to the <driver> element within the <disk> section that refers to your RiOS data store:
cache='none' io='threads'
Example:
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2' cache='none' io='threads'/>
<source file='/work/quicksilver/storage/myHost-vsh1-segstore1.img'/>
<target dev='vdb' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
</disk>
Save your changes to the domain.xml file, and restart the virtual machine.