Setting OpenVMS to automatically switch between GMT & BST

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garyrevell
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Setting OpenVMS to automatically switch between GMT & BST

Post by garyrevell » Fri Jan 29, 2021 5:48 am

Hi,

We've got a UK OpenVMS system that we want to configure such that it automatically changes the time when going from GMT <=> BST , and I've been asked to have a look at this.

But I'm not really a system manager so not sure where to start, someone has mentioned looking at the values in SYS$TIMEZONE_* but I don't know what values should be used. When we had the clocks go back in October the time had to be manually reset.

Currently the values are:

MYNODE> sh log sys$tim*
(LNM$PROCESS_TABLE)
(LNM$JOB_8919D380)
(LNM$GROUP_000104)
(LNM$SYSTEM_TABLE)

"SYS$TIMEZONE_DAYLIGHT_SAVING" = "1"
"SYS$TIMEZONE_DIFFERENTIAL" = "3600"
"SYS$TIMEZONE_NAME" = "BST"
"SYS$TIMEZONE_RULE" = "GMT0BST^1,M3.4.0/01,M10.5.0/02"

(LNM$SYSCLUSTER_TABLE)
(TMS$WINDOW_NAMES)
MYNODE>

Any help/advice or documentation pointers would be great.

Thanks

Gary


volkerhalle
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Re: Setting OpenVMS to automatically switch between GMT & BST

Post by volkerhalle » Fri Jan 29, 2021 11:32 am

Gary,

there is a system parameter: AUTO_DLIGHT_SAV

It needs to be set to 1, then OpenVMS will automatically switch to/from Daylight Savings Time on the date and time specified in SYS$TIMEZONE_RULE

Volker.


bhall
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Re: Setting OpenVMS to automatically switch between GMT & BST

Post by bhall » Mon Feb 01, 2021 6:33 pm

Gary,

The first thing you need to do is fix the current timezone configuration using the command procedure SYS$MANAGER:UTC$TIME_SETUP.COM This procedure and system time management in general is documented in the System Managers Manual found at https://vmssoftware.com/docs/VSI_SYS_MG ... _VOL_I.PDF.

After fixing the timezone configuration you can consider changing the SYSGEN parameter AUTO_DLIGHT_SAV as suggested by Volker. Although AUTO_DLIGHT_SAV is a dynamic system parameter, the system has to be rebooted or the Job Controller has to be restarted to set the Timer Queue Entry that will trigger the automatic time change at the end of GMT in March. The second volume of the System Manager's Manual https://vmssoftware.com/docs/VSI_SYS_MG ... VOL_II.PDF and the system management utilities manual https://vmssoftware.com/docs/VSI_SYS_MA ... VOL_II.pdf should be reviewed for help with SYSGEN and AUTOGEN.

Bill


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Re: Setting OpenVMS to automatically switch between GMT & BST

Post by willemgrooters » Wed Feb 03, 2021 10:35 am

If your VMS box is a server, I would suggest NOT using DST - no matter what timezone you are in: It can interfere with systems that rely on date and time a file is created, modified or accessed. As will be date and time of backup.

My system is ser up using GMT, no DST. It synchronises against to publi ly accessible time servers; The system functions as time server for my LAN, any system on this LAN has time set to CET + DST. That means that all times on these systems take the time difference into account, including DST. The only "problem" is that when you access times on the server, you have to take the time differences into account. But is saves me a lot of trouble when files are to be accessed by date and time.

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