I'm using Bacula as my backup system, with full backups going to an LTO2 tape drive, while differentials and incrementals go to a disk array on my main server, babylon4. The tape drive is currently attached to a separate machine, because babylon4 does not have a SCSI controller, nor a free PCI-X slot into which to install a fast enough SCSI controller. Both babylon4 (an amd64 box with dual LSI Logic SATA RAID controllers) and greatmachine (the tape host, a Sun V210) are running Solaris 10.
It would be advantageous to have the tape drive and the disk array at least logically connected to the same machine, as this would enable them to be controlled by the same storage daemon, which would allow me to copy and migrate jobs from disk to tape automatically. The best solution I have come up with to do this is to publish the LTO2 drive from greatmachine as an iSCSI target, then connect to it from babylon5 over a dedicated point-to-point gigabit link between greatmachine and babylon4. I have every part of this scheme accomplished except for the iSCSI part.
Where I'm running into the problem is this: I can find all kinds of articles all over the Web which mention that, while disk is the most common iSCSI target, tape devices and robotic tape libraries can also be iSCSI targets. However, every single example I have found discussing creation of iSCSI targets assumes that the backing store will be disk. (What's more, they almost without exception assume that the target will be a preallocated file on disk, not a raw device.) Although I can find examples that emulate tape using a disk backing store (though why on earth anyone would want to do such a thing is a complete mystery to me), I cannot find a single example, for Solaris or for any other operating system, that explains how to actually publish a real tape device as an iSCSI target. The closest I can get is the following:
iscsitadm create target -z 0 --lun 0 --type tape -b /dev/rmt/0n LTO2
which gives me the following result:
iscsitadm: Error Backing store is not a valid raw device
So: Can anyone tell me how to publish a real, physical tape drive on one Solaris 10 machine as an iSCSI target that I can then connect to from another Solaris 10 machine? I can find documentation on how to create a tape drive as an iSCSI target from Linux, but that doesn't really help me at all for Solaris.
(Yes, as a last resort, I could reinstall the V210 with Linux instead of Solaris. But, Linux on real Sun hardware? That's just wrong.)