Restrict tape dev access on an HSZ70 to a VMS node

[Doug_81]

I have a 2-node VMS cluster utilizing a HSZ70 disk controller. I've installed a DLT89 in the HSZ70 and am finding that the two systems don't play well with the new drive.

If node1 accesses the tape drive and later, node2 attempts to access the drive, it hangs it up and from that point on neither node can access the drive. A reboot is required to clear the access.

To prevent this, I've been trying to find a way to restrict the tape device to one node only.

The HSZ & the tape drive are configured as follows.

The controller:
HSZ70 ZG82115291 Firmware V70Z-0, Hardware H02

The tape device:
TAPE40200 passthrough tape 4 2 0 P400
DEC TZ89 (C) DEC 2150
Switches:
TRANSFER_RATE_REQUESTED = 20MHZ (synchronous 10.00 MHZ negotiated)

The unit:
P400 TAPE40200
Switches:
ACCESS_ID = ALL
State:
ONLINE to this controller
Not reserved
PREFERRED_PATH = THIS_CONTROLLER


Does anyone know if this can be done or if they can see a problem with the way the device/controller is configured?

[Uwe Zessin]

My guess is that the shared SCSI bus is the problem, not the presentation to both nodes. Due to the sequental nature of tape media it is not easy or even impossible to restart an operation once an error has happened. Any bus reset will be a great disturbance - I've once read somewhere that some stupid tape drive did even write a tape mark during reads!

According to the documentation, at least in HSOF V7.3, you cannot control host access to passthrough devices.

[Robert Gezelter]

Doug,

A small suggestion, purely on a software level.

To prevent accidents while resolving the configuration issue, look at putting an device ACL on the second system to prevent users other than the system manager from using the tape by accident from the second system.

There should be a better long term solution, but the ACL will prevent users from creating an accident in the interim.

- Bob Gezelter, http://www.rlgsc.com

[Robert_Boyd]

What version(s) of OpenVMS are you running on the host systems?

What are the SCSI I/O controllers you're using to talk to the HSZ70? And what firmware revisions are they?

[Doug_81]

Uwe:
Perhaps I wasn't clear enough.
Here's an example of what has happened:
Access the tape drive from node1 works ok.
Then access the tape drive from node2. This also works ok, except from this point on, the tape drive is no longer available to node1.

I'm sorry but I don't have the error message anymore and I can't be sure what had to be rebooted to restore the tape drive to node1.
i.e. node1, node2 or the HSZ controller.

Both nodes are Alphaservers.
Node1 is running OpenVMS V7.3
Node2 is running OpenVMS V7.1-1H2

Both nodes are current with all patches relavent to their version.

Robert Gezelter:
Not a bad idea for a workaround, thanks.

Robert Boyd:
The versions are listed above.
"What are the SCSI I/O controllers you're using to talk to the HSZ70?"

I'm sorry but I don't understand your question.The HSZ70 is the controller.

[Ian Miller.]

I think Robert ment what scsi interface card where you using in your alphaservers e.g KZPBA-AA and so on.

Re using ACL, remember to change the device protection to block access i.e. SET SECURITY/CLASS=DEVICE MKxxx/PROT=(S:RWLP,O,G,W)
should do it.

[Robert Gezelter]

Ian,

Because of the severity of the side-effect, I was thinking more along the lines of an ACL with an identifier granted to a VERY VERY SMALL group of users.

Unless I am the only user in a systems group (and that includes all users holding SYSPRV), I would not allow SYSTEM ask with a protection mask. In far too many sites, relatively untrained operators have accounts with SYSTEM UICs, which could be a serious hazard in this case.

Just my US$ 0.02.

- Bob Gezelter, http://www.rlgsc.com

[Doug_81]

Thanks Ian but I'm afraid I don't have that information handy. I'll see if I can dig it up.

Re. The ACL. I'm tempted to go one step more.
e.g. SET SECURITY/CLASS=DEVICE MKxxx/PROT=(S:,O,G,W)

I run backups via Node1 - only. If anyone accesses this device from Node2, I'm hooped.

Robert G:
I agree. It's very common to find VMS system with lots of accounts in the system group or at least with sysprv. Although, this system is in very good shape. I can count the users in the system group (or with sysprv), on one hand (including myself).

Also, being a Canadian, your US$ 0.02 is a lot!

[Albert Öttl]

Hi Doug,
did you check the SPD : http://h18000.www1.hp.com/info/SP6481/SP6481PF.PDF
There are some restrictions and caveats in using the TZ89 on an HSZ70.

Did you also use this 0.2m converter cable?

Just my 0.02 EUR.

[Doug_81]

Thank you for the heads up re. the TZ89/HSZ70 incompatability.

I haven't had any problems with this configuration for a long time. It may be related to the activity on the controller. The tape drive is only used on the weekends when there is very little disk activity.

Nevertheless, I have scheduled a change to move it from the hsz70 to an internal connection on one of the alphas.