Categories
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

[code]

Target iqn.2007-04.com.example:tape0
Lun 0 H=4,C=0,I=0,L=0,Type=rawio
Type 1
InitialR2T No
ImmediateData Yes
xMaxRecvDataSegmentLength 262144

Target iqn.2007-04.com.example:usb0
Lun 1 Path=/dev/sdb,Type=fileio
[/code]

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.

Categories
General

Touchgraph Google Browser

Saw the TouchGraph Google Browser mentioned on an irc channel today. Touchgraph make graph based visualisation, showing spatial relationships and correlations between data. The google browser uses results from a google search as the input; Touchgraph have Facebook and Amazon visualisations as well, but I guess their main business is visualising data warehouses and the like.