KAGRA Logbook

DGS (GPS)

shinji.miyoki - 13:33 Saturday 28 December 2024 (32179)

GPS troubles

Around UTC0:00 (9:00 JST) today, the GPS got into trouble as shown in Figure 1. Because of this trouble, some applications such as ndscope could not be used.

Michimura-kun guessed

the leap data cached from IETF page is in /usr/share/zoneinfo/leap-seconds.list, and this file says, "File expires on 28 December 2024".
Since there is no leap seconds after 2017, and we can just update the expiration timestamp Or update leaps.py (gpstime) with the latest file?

He also found the messages, "ietf.org is no longer serving this file. Use https://data.iana.org/time-zones/data/leap-seconds.list instead." Oshino-kun also said, "Maybe we only need to update tzdata package to update leap-seconds.list file.". However, a careful manner seems to be necessary for the simultaneous update of the GPS file for all servers, and it used to be done by only YamaT-san.

As an emergency measure, we decided to update the GPS file only in k1ctr0 in the DAB control room to use this server as a remote desktop server from the KAGRA site for today's activities, and Oshino kun performed the attached command for the update. Then ndscope could be active in this server.

Of course, we need the GPS file update for all servers.

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Comments to this report:

takahiro.yamamoto - 14:13 Sunday 29 December 2024 (32185)

Sorry for delayed response. I was unable to respond yesterday due to some personal problems.

Because there was no report about the problem after updating k1ctr0, I applied the package update for all workstations.
I haven't done enough operation test yet with new package. Detailed operation test will be done in the next week or 2 weeks later.

takahiro.yamamoto - 20:40 Friday 17 January 2025 (32382)

This issue was mitigated by a new version of the gpstime package which is released for Debian12 in last week.
The new version of this package was deployed to all workstations.

When leap seconds information in the system time zone file is expired, the new version of gpstime package finds an online leap seconds info. from multiple sites. Of course, same problem is reproduced when all referred sites are expired. But the risk is reduced from the old version.

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This update was applied between v0.7.0 and v0.8.0.
https://git.ligo.org/cds/software/gpstime/-/commits/master?ref_type=HEADS

For Debian12, only v0.6.2 and v0.8.2 are distributed in the stable repository for now. So we need to install v0.8.2.
controls@k1ctr4:~$ apt-cache madison gpstime gpstime | 0.8.2-1 gpstime | 0.6.2-1