Revision as of 19:12, 27 November 2011

Xen blktap2 driver

Xen blktap2 is a successor to the old blktap1 disk backend driver. See blktap wiki page for information about the old blktap1.

Xen blktap2 support is included in the Xen version 4.0 released in Apr 2010.

This wiki page is still under construction. Feel free to contribute/fix things!

Example for Xen 4.0.0 "/etc/xen/<guest>" cfgfile for RAW images:

disk = [ "tap:tapdisk:aio:/path/images/disk.img,xvda,w" ]

Example for Xen 4.0.0 "/etc/xen/<guest>" cfgfile for VHD images:

disk = [ "tap:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]

Example for Xen 4.0.0 "/etc/xen/<guest>" cfgfile for QCOW2 images:

disk = [ "tap:qcow2:/path/images/disk.qcow2,xvda,w" ]

Notice: In Xen 4.0.0/4.0.1 don't mix file and tap simultaneously, in this case domU unable to see any disk device. May be bug or feature!

To define ISO images use:

disk = [ "tap:qcow2:/path/images/disk.qcow2,xvda,w","tap:tapdisk:aio:/path/images/somedistro.iso,xvdb,r" ]

Example for Xen 4.0.1 "/etc/xen/<guest>" cfgfile for RAW images:

disk = [ "tap2:tapdisk:aio:/path/images/disk.img,xvda,w" ]

Example for Xen 4.0.1 "/etc/xen/<guest>" cfgfile for VHD images:

disk = [ "tap2:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]

More information about VHD support can be found from the README file below.

blktap2 functionality requires support from Xen tools and also a blktap2 driver in the dom0 kernel.

Please see XenKernelFeatures wiki page for more information about Xen kernels having blktap2 driver.

Latest blktap2 README from xen-unstable source repository: http://lxr.xensource.com/lxr/source/tools/blktap2/README

Announcement of the blktap2 patches with information about features: http://lists.xensource.com/archives/html/xen-devel/2009-02/msg00721.html
blktap2 patches that were merged into xen-unstable in May 2009 for Xen 4.0.0: http://lists.xensource.com/archives/html/xen-devel/2009-05/msg00966.html

@@ Line 16: / Line 16: @@
-<pre><nowiki>
+<pre>
 disk = [ "tap:tapdisk:aio:/path/images/disk.img,xvda,w" ]
-</nowiki></pre>
+</pre>
 Example for Xen 4.0.0 "/etc/xen/<guest>" cfgfile for VHD images:
-<pre><nowiki>
+<pre>
 disk = [ "tap:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]
-</nowiki></pre>
+</pre>
 Example for Xen 4.0.0 "/etc/xen/<guest>" cfgfile for QCOW2 images:
-<pre><nowiki>
+<pre>
 disk = [ "tap:qcow2:/path/images/disk.qcow2,xvda,w" ]
-</nowiki></pre>
+</pre>
 Notice: In Xen 4.0.0/4.0.1 don't mix '''file''' and '''tap''' simultaneously, in this case domU unable to see any disk device. May be bug or feature!
@@ Line 39: / Line 39: @@
-<pre><nowiki>
+<pre>
 disk = [ "tap:qcow2:/path/images/disk.qcow2,xvda,w","tap:tapdisk:aio:/path/images/somedistro.iso,xvdb,r" ]
-</nowiki></pre>
+</pre>
 == Changes in Xen 4.0.1 blktap2 support ==
@@ Line 47: / Line 47: @@
-<pre><nowiki>
+<pre>
-disk = [ "tap2:tapdisk:aio:/path/images/disk.img,xvda,w" ]</nowiki></pre>
+disk = [ "tap2:tapdisk:aio:/path/images/disk.img,xvda,w" ]
+</pre>
 Example for Xen 4.0.1 "/etc/xen/<guest>" cfgfile for VHD images:
-<pre><nowiki>
+<pre>
-disk = [ "tap2:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]</nowiki></pre>
+disk = [ "tap2:tapdisk:vhd:/path/images/disk.vhd,xvda,w" ]
+</pre>
 == VHD support ==