Loose TZ89 on HSZ70

[Doug_81]

Installed a TZ89 on a HSZ70 5 months ago.
Since then I have lost availability to the tape drive, on two occasions. The only way to recover it is to restart the controller.

Although it seems to be infrequent, it is a royal pain because it requires me to get all the users off the cluster and shut down the cluster before restarting the controller.

I understand that this shouldn't be necessary since the disks will go into mount verify state and then "should" recover after the controller restarts. However, too often have I experienced problems when disks go in and out of mountverify, so I'm somewhat gun-shy.

Configuration:
HSZ70
HSZ70 ZG82115291 Firmware V70Z-0, Hardware H02

2 Node Cluster:
AlphaServer 1200 5/400 - OpenVMS V7.3
and
AlphaServer 1000 4/233 - OpenVMS V7.1-1H2

Anyone have any ideas?
Thanks,
Doug

[Uwe Zessin]

Is the TZ even supported on the HSZ?

I am pretty sure that shared tape is not supported in an OpenVMS cluster. Disk I/O can be restarted easily - tape drives get very upset upon a bus reset.

[Doug_81]

"...shared tape is not supported in an OpenVMS cluster"?!?

That's news to me. I've always had a tape drive installed in a controller cabinet to enable access from all cluster nodes for backup/restore.

This device is configured on the HSZ70 as a Passthrough device. This is discussed in the HSZ70 controller Reference manual as follows:

"A passthrough container bypasses controller processing and allows the host to have direct access to the device. A passthrough device appears as if it were connected directly to the host bus rather than to the controller. Use passthrough containers to communicate with tape devices and tape loaders because they do not require the controller for optimum operation performance."

[Uwe Zessin]

I was talking about SCSI tape drives, if that wasn't clear.

Here is what the documentation says:
http://h71000.www7.hp.com/doc/732FINAL/6318/6318pro_020.html#scsi_req_tab

Table A-1 Requirements for SCSI Multihost OpenVMS Cluster Configurations

SCSI tape, floppies, and CD-ROM drives:

You cannot configure SCSI tape drives, floppy drives, or CD-ROM drives on multihost SCSI interconnects. If your configuration requires SCSI tape, floppy, or CD-ROM drives, configure them on single-host SCSI interconnects. Note that SCSI tape, floppy, or CD-ROM drives may be MSCP or TMSCP served to other hosts in the OpenVMS Cluster configuration.

[Doug_81]

Hi Uwe:
I know it's been a long time with any response to this one, but what happened is I reseated the tape drive and made sure that is is only accessed from one node. The result is that it hasn't failed.

After I reseated the drive, a lot of other things happened which had priority for my time and I forgot about this problem. Out of sight, out of mind....I only returned to it because someone (Jan van den Ende) reminded me that there are some old responses which have not had any points assigned to them.

Thank you for your comments. I thought that the HSZ70 controller would support a tape drive connected as long as it was configured as a passthrough device, as indicated in the HSZ70 manual.

e.g.
"Use passthrough containers to communicate with tape devices and tape loaders because they do not require the controller for optimum operation performance."

I also found a comment from the OpenVMS wizard, "Multihost SCSI configurations do not permit the configuration of tape or other "non-reentrant" devices on the shared SCSI bus".

So, now I'm totally confused: Does it or doesn't it?

Assuming this is not a supported configuration and the only reason it works is becasue the device is only accessed from one node in the cluster, there is no point in plugging the tape in the HSZ70, wasting 3 slots.

I would be further ahead to plug it into the local bus on one of the cluster nodes. The node would then serve the tape device to the cluster and therefore make it available to the cluster. Granted, for perfomance reasons, the access to the tape drive from other nodes would not be recommended.

Comments and/or suggested are geatly appreciated.

Doug

[Jason Lee3 · Accepted solution]

Hi Doug,

I don't like the TZ89 being on the HSZ70. We don't see it in the field as it makes sense to separate the disk and tape subsystems given the issues that the tape solution is likely to give. As you say the inconvenience of having disk disruption to remdiate a tape issue is very high to users. I agree you would be wise to move the TZ89 out of the HSZ70's BA370 enclosure, wip it out of the SBB housing and attach directly to a node (In an ext. case probably).
Also on a housekeeping level I note you are running only V7.0Z ACS on the controllers. I would have expected V7.7z for your level of OpenVMS. I also note the ACS cards have no patches applied to them (-0). I never like to see this as the patches address some major issues and they are so easy to apply.

Regards

Jason

[Doug_81]

Ok, I think you've both answered my question. I'll move the tape drive from the HSZ70 to the local SCSI on one of the nodes of the cluster.

Jasen:
You brought up another issue which I need to look into - that of the firmware version of the HSZ70. thank you.

Seems also that I was a little stingy with the points on this one. Uwe, If you could comment, I can correct this.

Doug