Blktap2

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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!

Usage

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" ]

Changes in Xen 4.0.1 blktap2 support

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" ]

VHD support

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

Dom0 kernel drivers for blktap2

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.

Documentation

Latest blktap2 README from xen-unstable source repository: http://xenbits.xensource.com/hg/xen-unstable.hg/file/tip/tools/blktap2/README

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