linux NSP WLUG Xen

iSCSI for SCSI device passthrough under Xen Enterprise

I recently had to add a SCSI tape drive to a Xen Enterprise server, and needed to use BackupExec under one of the Windows domU’s as the backup software. Luckily, Greig did this a few months ago already using the iSCSI Enterprise Target, and put his notes up on the WLUG Wiki here.

I hit one problem however – when using NTBackup to test the system, it would write about 20 MB to tape, then fail. Greig pointed out he’d only ever used BackupExec, which was the software that was going to be used finally anyway, so I installed that and then it worked fine.

Also, going one step further, it’s possible to use the same technique to push USB mass storage devices over iSCSI to domUs. As Xen Enterprise doesn’t have a nice way of passing USB mass storage devices through to domUs yet, this is a very good solution in the interim


Lun 0 H=4,C=0,I=0,L=0,Type=rawio
Type 1
InitialR2T No
ImmediateData Yes
xMaxRecvDataSegmentLength 262144

Lun 1 Path=/dev/sdb,Type=fileio

As it refers to the scsi device, which will change if you unplug and re-insert a USB block device, it makes a lot of sense to use udev to map your USB mass storage device to a specific /dev entry.

I don’t have a feeling for how robust this is yet.

5 replies on “iSCSI for SCSI device passthrough under Xen Enterprise”

This document provides instructions for configuring StarWind iSCSi Target and Citrix XenServer. It includes instructions on configuring StarWind Server including enabling XenServer Support and preparing storage; and configuring XenServer. The document includes detailed step-by-step instructions, illustrations and screen shots to aid users.

Can someone please help me?
I’ve tried to pass a SCSI tape library through as iSCSI. I successfully made all the necessary steps, but I cannot connect with any Initiator software. Can someone tell me what i did wrong? When I try to connect with the xen host itself (New Storage Repository), it find itself correctly but then crashes and restarts. So I think the iscsi target configuration itself is correct. i even disabled the host’s and the guest’s firewall…

Thank You,

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