Fujitsu BS2000, Руководство пользователя

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Time synchronization Architecture and strategies
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U41855-J-Z125-3-76
Repercussions of changing the system time on the Server Unit
When changes are made in the Server Unit’s time management, greater or lesser leaps in
time can occur in the following cases:
●
When the local time is set manually (if no NTP server is configured).
●
When an NTP server is entered for the first time (possibly also when modifying the NTP
configuration).
In the current BS2000 session, leaps in time have the following effects:
●
The modified time is forwarded to BS2000. Every 15 minutes BS2000 compares its time
with the SVP clock. If a time difference is detected during synchronization, the time is
adjusted over a period which is approx. 4 times as large as the time difference (i.e. an
adjustment of 2 minutes takes 8 minutes). As a result, time changes on the Server Unit
arrive in BS2000 with a corresponding delay.
●
BS2000 accepts a time change of at most 15 minutes.
If a leap in time is
Î
15 minutes, the time adjustment is made without issuing any
messages. If the leap in time is greater, the time is not adjusted. A console message
indicates that from this point the BS2000 session will run only using its own time from
the TODR. At intervals of 15 minutes, BS2000 repeatedly compares the times, and
synchronizes them only if the time difference is less than 15 minutes.
Details on configuring the system time on the MU are provided in the section “Setting the
system time (time synchronization or local)” on page 214 .
Further details on system time management in BS2000 can be found in the manual
"Introduction to System Administration" [
10 ].
Time synchronization in XenVM systems
When the XenVM is started, the operating system which is started on it takes over the
current Linux time as its local time setting. In the further operations of the XenVM system
the local time is independent of the time configuration of the Server Unit and can be
corrected only with the current operating system’s means. The time can either be set
manually here or be synchronized via an NTP server. However, such settings only ever
apply for the active session.
Details on configuring the system time on the MU are provided in the section “Setting the
system time (time synchronization or local)” on page 214 .
Further details on system time management can be found in the documentation of the
operation system used.