Installation guide

<address type='drive' controller='0' bus='0' unit='0'/>
</disk>
<disk type='block' device='disk'>
<driver name='qemu' type='raw'/>
<source dev='/dev/disk/by-path/ip-192.168.122.170:3260-iscsi-iqn.2004-
04.rhel:rhel5:iscsi.kvmguest-lun-2'/>
<target dev='hdb' bus='ide'/>
<shareable/>
<alias name='ide0-0-1'/>
<address type='drive' controller='0' bus='0' unit='1'/>
</disk>
<controller type='ide' index='0'>
<alias name='ide0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01'
function='0x1'/>
</controller>
<interface type='network'>
<mac address='52:54:00:0a:ca:84'/>
<source network='default'/>
<target dev='vnet1'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04'
function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/28'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/28'>
<source path='/dev/pts/28'/>
<target port='0'/>
<alias name='serial0'/>
</console>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='5901' autoport='yes' keymap='en-us'/>
<video>
<model type='cirrus' vram='9216' heads='1'/>
<alias name='video0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02'
function='0x0'/>
</video>
</devices>
</domain>
There are two important items of note in this output:
The guest uses the large /dev/disk/by-path paths to reference the LUNs. As described
earlier, this is so that file names and paths will remain constant.
The second disk has the <shareable/> flag set. Critical for the disk to be safely shared
between guests, this ensures that the SELinux labelling will be appropriate for multiple
guests to access the disk and that all I/O caching is disabled on the host.
For migration of guests between hosts to succeed, some form of shared storage is required. Although
NFS is often used for this purpose, the lack of SELinux labelling for NFS means there is limited sVirt
protection between guests. This lack of sVirt support could allow one guest to use another guest's
disks, which is usually undesirable.
Using iSCSI provides full sVirt isolation between guests to the same degree of non-shared storage.
Red Hat En t erp rise Lin ux 5 Virt ualizat ion Guid e
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