Meaning of "target" in virsh XML VM definitions

Question

I recently found that the target=hda tag in virsh was actually not translating into guest OS (guest OS's use /dev/sdX as the disk device names, in general, it seems).

virt-install and /dev/hda vs. /dev/sda

I am thus now wondering, what is the meaning of the "target dev" declarations which comprise my virt-install / virsth dumped XML files?

<disk type='file' device='disk'>
    <driver name='qemu' type='raw' cache='none'/>
    <source file='/VirtualMachines/bthadoop-sda.raw'/>
    <target dev='hda' bus='ide'/>
    <alias name='ide0-0-0'/>
    <address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<disk type='file' device='disk'>
    <driver name='qemu' type='raw' cache='none'/>
    <source file='/var/lib/libvirt/images/sandbox1'/>
    <target dev='hdb' bus='ide'/>
    <alias name='ide0-0-1'/>
    <address type='drive' controller='0' bus='0' target='0' unit='1'/>
</disk>

Answer 1

查看libvirt 域 XML 文件的参考文档，特别是本节：硬盘驱动器、软盘、CDROM。

目标

目标元素控制磁盘暴露给来宾操作系统的总线/设备。dev 属性指示“逻辑”设备名称。指定的实际设备名称不保证映射到来宾操作系统中的设备名称。将其视为设备订购提示。

可选的总线属性指定要模拟的磁盘设备的类型；可能的值是特定于驱动程序的，典型值为“ide”、“scsi”、“virtio”、“xen”、“usb”或“sata”。如果省略，则根据设备名称的样式推断总线类型（例如，名为“sda”的设备通常使用 SCSI 总线导出）。

可选属性托盘指示可移动磁盘（即CDROM或软盘）的托盘状态，该值可以是“打开”或“关闭”，默认为“关闭”。注意，托盘的值可以在域运行时更新。

从 0.0.3 开始；bus自 0.4.3 起的属性；tray 自 0.9.11 起的属性；" usb"属性值自0.4.4之后开始；“ sata”属性值从0.9.7开始