Novell LINUX ENTERPRISE SERVER 11 - VIRTUALIZATION, Руководство пользователя

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6.13 xm block-list Device Numbers
Virtual devices are named internally in Xen using the Linux-style major and minor
numbers. This is true even for non-Linux virtual machines. The number returned from
xm block-list
is a decimal representation of the combined major and minor
numbers.
For example, if a virtual machine’s virtual disk is designated as
hda
, the number returned
from
xm block-list
is 768.
hda
has major number 3 and minor number 0. The
major number is stored as a high-order byte; the minor is the lower byte. A decimal
representation is (3*256)+0 = 768. Another example,
sda3
has major number 8 and
minor number 3, so its decimal representation is (8*256)+3 = 2051.
Of course, it is possible to manually work backwards from a number to discover the
human-readable device name. For your reference, some common mappings are listed
in the following table.
/dev/hda 768
/dev/hdb 832
/dev/hdc 5632
/dev/hdd 5696
/dev/sda 2048
/dev/sdb 2064
/dev/sdc 2080
/dev/sdd 2096
/dev/xvda 51712
/dev/xvdb 51728
/dev/xvdc 51744
/dev/xvdd 51760
6.14 File-Backed Virtual Disks and
Loopback Devices
When a virtual machine is running, each of its file-backed virtual disks consumes a
loopback device on the host. By default, the host allows up to 64 loopback devices to
be consumed.
Virtualization: Configuration Options and Settings 69