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NTP and Alpha Hardware Clock

 
Rod Henderson
Occasional Advisor

NTP and Alpha Hardware Clock

Does NTP update the hardware clock on an Alpha?

The system is a Compaq AlphaServer DS20E 666 Mhz running OpenVMS V8.3

I assume on startup, the system time is set by a battery powered hardware clock. With the system time being disciplined by NTP, is the hardware clock automatic set to the system time? Maybe this is only done on system shutdown.
7 REPLIES 7
Hoff
Honored Contributor

Re: NTP and Alpha Hardware Clock

The SHUTDOWN.COM shutdown procedure does set the saved time with a SET TIME command.

Rod Henderson
Occasional Advisor

Re: NTP and Alpha Hardware Clock

I was not searching right directories. I now have found the correct file and the set time statement.

Now the next question: Does NTP do this periodically? My only concern is when we get a non-graceful system shutdown, ie crash after he machine has been running for a couple of months.
Hoff
Honored Contributor

Re: NTP and Alpha Hardware Clock

AFAIK, no.

Neither the TCP/IP Services ntp server nor DECnet-Plus DTSS touch the TOY or the BB_WATCH in any fashion.

This same basic case was at the core of the yearly "fun" with some obscure VAX TOY clock "maintenance" requirements:

http://labs.hoffmanlabs.com/node/615
Rod Henderson
Occasional Advisor

Re: NTP and Alpha Hardware Clock

Thanks.
Rod Henderson
Occasional Advisor

Re: NTP and Alpha Hardware Clock

Looks like I have to rely on SHUTDOWN.COM
RBrown_1
Trusted Contributor

Re: NTP and Alpha Hardware Clock

Why not create a periodic batch job that does $ SET TIME ?
Hoff
Honored Contributor

Re: NTP and Alpha Hardware Clock

The batch job (or most any scheduling package) will most certainly work, but this looks to be the reverse-case at the core; the BB_WATCH is almost certainly going to drift away from the values returned by the ntp servers (and I trust the ntp servers more), so using ntpdate at boot-time (entirely possible, but not exactly cleanly due to the way the TCP/IP Services startup is sequenced) to synchronize the running system time with the ntp server before launching would seem the most efficient approach.

The one wildcard here is whether TCP/IP Services does this quick-synch with ntpdate itself; I haven't looked in detail. Based on a quick search, it doesn't. Or it doesn't seem to do this using ntpdate.

There may well be some other mechanism(s) that can be used here.

And yes, the periodic SET TIME does address other issues.