CHAPTER 4 Functions provided by the PRIMEQUEST 2000 series
4.6 Clock feature
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Adjusting the time using NTP client function of the MMB
OS
The OS reads the RTC (PCH-RTC) which is built-in the PCH when booting, and
manages the time of day
by itself, using the timer while running.
The PCH-RTC is driven by a battery on the SB (hereafter
referred to as SB battery).
BIOS
The PCH-RTC is driven by the SB battery, and the PCH-RTC stops when the SB battery is run out.
BIOS acquires time from MMB to modify PCH-RTC at boot.
Thus, if PCH-RTC stops due to exhaustion of SB battery or if Home SB is switched due to Reserved SB or
SB degradation, correct time is read out at OS boot.
When the SB battery runs out, the BIOS reflects the time of the MMB in the PCH-RTC.
BMC
The RTC of the BMC synchronizes with the RTC of the MMB immediately after the mounting the SB and the
AC is turned on.
If the MMB time is modified manually, the BMC time synchronizes with the MMB time.
4.6.2 NTP client
In PRIMEQUEST 2000 series, the MMB becomes an NTP client to synchronize the time with an external
NTP server.
When NTP servers in an external network are not connected to the PRIMEQUEST 2000 series, it is
recommended to use an NTP server device that uses an external clock. As shown in the following figure, the
MMB can access another NTP server and synchronize the time with the NTP server. For stable NTP
operation,
each NTP client should have several NTP servers (at least three for RHEL)
.
Notes
When using more than one NTP server, use them in the same stratum (layer).
FIGURE 4.7 Diagram of time synchronization (of three 3 NTP servers)
Only one NTP server can be also specified. In this case, if the communication with the specified NTP server
is disconnected, the NTP client loses the NTP server as there is no other target to synchronize. Until
communication with the NTP server is re-established, the NTP client cannot adjust the time through the NTP.
Therefore, if the time cannot be adjusted through the NTP, the time gap between the systems may increase,
which could lead to malfunction of the middleware or application.
