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Documentation: Add section about iSCSI LUNS to qemu-doc

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Add a new section about using iSCSI LUNs with qemu
and provide a short example on how to set up a target and access it
using the built-in initiator

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Ronnie Sahlberg 2011-11-12 11:06:30 +11:00 committed by Kevin Wolf
parent 3f5bd4e1b8
commit 00984e3953
1 changed files with 56 additions and 0 deletions
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qemu-doc.texi
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@ -421,6 +421,7 @@ snapshots.
* disk_images_fat_images:: Virtual FAT disk images
* disk_images_nbd:: NBD access
* disk_images_sheepdog:: Sheepdog disk images
* disk_images_iscsi:: iSCSI LUNs
@end menu
@node disk_images_quickstart
@ -695,6 +696,61 @@ qemu-img create sheepdog:@var{hostname}:@var{port}:@var{image} @var{size}
qemu sheepdog:@var{hostname}:@var{port}:@var{image}
@end example
@node disk_images_iscsi
@subsection iSCSI LUNs
iSCSI is a popular protocol used to access SCSI devices across a computer
network.
There are two different ways iSCSI devices can be used by QEMU.
The first method is to mount the iSCSI LUN on the host, and make it appear as
any other ordinary SCSI device on the host and then to access this device as a
/dev/sd device from QEMU. How to do this differs between host OSes.
The second method involves using the iSCSI initiator that is built into
QEMU. This provides a mechanism that works the same way regardless of which
host OS you are running QEMU on. This section will describe this second method
of using iSCSI together with QEMU.
In QEMU, iSCSI devices are described using special iSCSI URLs
@example
URL syntax:
iscsi://[<username>[%<password>]@@]<host>[:<port>]/<target-iqn-name>/<lun>
@end example
Username and password are optional and only used if your target is set up
using CHAP authentication for access control.
Alternatively the username and password can also be set via environment
variables to have these not show up in the process list
@example
export LIBISCSI_CHAP_USERNAME=<username>
export LIBISCSI_CHAP_PASSWORD=<password>
iscsi://<host>/<target-iqn-name>/<lun>
@end example
Howto set up a simple iSCSI target on loopback and accessing it via QEMU:
@example
This example shows how to set up an iSCSI target with one CDROM and one DISK
using the Linux STGT software target. This target is available on Red Hat based
systems as the package 'scsi-target-utils'.
tgtd --iscsi portal=127.0.0.1:3260
tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \
-b /IMAGES/disk.img --device-type=disk
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \
-b /IMAGES/cd.iso --device-type=cd
tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
qemu-system-i386 -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
-cdrom iscsi://127.0.0.1/iqn.qemu.test/2
@end example
@node pcsys_network
@section Network emulation