xen支持的块设备

1. 物理块设备（Dom0中的物理块设备，如逻辑卷）
    phy:/dev/cdrom
    phy:/dev/xenvg/vm1
2. 磁盘镜像
    file:/root/tst.iso（使用loopback）
    nbd: ip_port （网络块设备）
    tap:cdrom:/dev/sr0（CD设备）
    tap:aio:/path/file  （blktap）
    tap:qcow:/mnt/disks/sles10sp1.iso.qcow（QEMU磁盘镜像）
    tap:vmdk:/mnt/disks/sles10sp1.iso.vmdk（Vmware磁盘镜像）
3. ISCSI设备：
    iscsi:iqn.2001-04.com.acme@0ac47ee2-216e-452a-a341-a12624cd0225
4. NPIV设备：
    npiv:210400e08b80c40f

file与tap的区别

file: uses dom0 kernel page cache, and thus might give better performance than phy: or tap:aio:,
but it's also more insecure because of the caching.

tap:aio: uses direct IO, so it bypasses dom0 kernel caches, and works like phy: in that sense.

blktap1 provides also other modes than :aio, like: qcow, but those were not very stable or fast,
    disk = ['tap:aio:<FILENAME>,sda1,w']
    disk = ['tap:qcow:<FILENAME>,sda1,w']
so blktap2 was developed. for blktap1 see: http://wiki.xensource.com/xenwiki/blktap .

blktap2 also has vhd image support including snapshots and cloning.
    disk = [ "tap:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]
    disk = [ "tap2:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]
See here: http://wiki.xensource.com/xenwiki/blktap2 .

本文转自feisky博客园博客，原文链接：http://www.cnblogs.com/feisky/archive/2012/01/31/2332809.html，如需转载请自行联系原作者