How to reset device error count on OpenVMS V6.2-1H3

[Jon Pinkley]

Gordon,

The supported way to clear device error counts in VMS 6.2 is to reboot. As others have said, the change in value is more interesting than absolute error count.

"set device/reset" actually writes an errlog message recording the fact that it reset the device error count. As far as I know, none of the user-contributed error resetting programs do this (and it they did, they probably did it in a different way).

Any software that runs with cmkrnl or cmexec privilege enabled has permission to crash a system. I have used ZDEC and looked at the code and from what I remember, it was written with safeguards in place to prevent crashing the system.

You can also use the kernel debugger DELTA to clear the error counts, and this requires no "extra" software to be installed, but doing that is in my opinion much more dangerous than using a utility like ZDEC.

The safest is to just live with the error counts until you reboot.

Since your example used a tape device, what is your goal in resetting the error count?

Are you trying to determine if the tape drive needs cleaned? If so, depending on the drive there may be better ways to get the info (using SCSI commands passed directly to the tape drive via the MKDRIVER SCSI pass-through).

In our backup command procedures, we get the device error count before backup starts, and again after the backup is complete. The differences are what we want to be aware of. A bad tape, or poor SCSI cable connection can cause a lot of tape errors, but as long as the absolute number does not increase during the backup, then we don't worry about it.

Jon