Asset ID:	1-72-1018924.1
Update Date:	2009-01-29
Keywords:

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Solution Type  Problem Resolution Sure

Solution  1018924.1 :   Time of Day (TOD) drifts 2 or more seconds per day  


PreviouslyPublishedAs
230772

Symptoms
Sun Fire[TM] V480/490/880/880z/890 product family TOD (Time of Day) capability is enabled by the SuperIO chip. But this TOD will drift a minimum of 2 seconds per day.

Resolution
On Sun Fire V480/490/880/880z/890, use NTP server for time adjustment and thus keeping time accurate.

Product
Sun Fire V890 Server
Sun Fire V880z Visualization Server
Sun Fire V880 Server
Sun Fire V490 Server
Sun Fire V480 Server

Internal Comments
For the internal use of Sun Employee's.

This is Don Palko of VSP PTS Engineering. Feb 17, 2005

The following paper is one we in VSP PTS requested from
Volume Server Systems (VSS) Development Engineering.
That so we can send it to Sun employees and especially
customers when and as needed. Sun employees - you
may send the below copy to customers when an official
Sun position statement is requested. It is NOT Company
Confidential and no level of NDA is required. Even given
that I thought it best that the public section of this Technical Instruction
remain as brief as writen by Hirokazu Kaneko and this
addendum be located in the Internal-Only section.

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"June 2005
Sun Engineering Summary
Part/Issue SuperIO PC97317 Time of Day Functionality
Organization Enterprise Systems - Volume Server Systems

The National Semiconductor SuperIO PC97317 has been the subject of
on-again/off-again Sun[TM] engineering investigation due to its performance
on the VSS 480/490/880/890 product family. This has resulted in several
operations and customer complaints including BUG ID: 4806138. The
issue comes down to  understanding the functionality and accuracy of
the Time of Day* (TOD) clock built into this multipurpose device (SuperIO).
We [Sun VSS Development Engineering] met with Sun's ACE (Advanced
Component Engineering) group to better understand the original
requirements of the TOD clock on our platforms.

The SuperIO's RTC (Real Time Clock) is a digital circuit built in to the
device. As such, National does not specify a tolerance around the
accuracy of their  internal circuit.  We do control the accuracy of the
input logic that drives the TOD, which consists of a 32.768Khz crystal,
a 8.2pf capacitor, a 12pf capacitor, a 100k Ohm resistor and a 20MOhm
resistor.  Also factored in are the specific  layout and routing considerations
that are outlined in National application note, AN-1284.  Based on an
analysis done by Engineering,  the PPM of the Crystal we have selected,
our absolute best tolerance should be roughly 1.78 seconds per day.
Given the tolerance of the rest of the components in the circuit, and some
engineering judgment, we believe that the TOD circuit will drift a minimum
of 2 seconds per day. With the National SuperIO and process variations
remaining unknowns, Sun Engineering can not specify a maximum drift value.
This represents an accurate data driven analysis by Sun Engineering.  

In summary, Sun Development engineering did not design the TOD circuit
with any accuracy specification in mind. This is the result of there being
no requirement then or now from the field to dictate a TOD specification.
Further, Sun Engineering recommends using the SNTP (Simple  Network
Time Protocol) to synchronize the TOD clocks on the internet.

For new system development,Sun Engineering recommends Operations
request a TOD requirement be added to all future system designs. Also
Sun Engineering recommends that Operations create a reasonable test
specification based on  demonstrated results in their current test
environment.

*Also referred to as Run Time Clock (RTC)"
TOD, RTC, 480, 490, 880, 890, daktari, silverstone, cherrystone, sebring, SuperIO
Previously Published As
83895

Change History
Date: 2006-02-19
User Name: 97961
Action: Approved
Comment: - Applied trademarking
- Audience changed to "Contract" per FvF http://kmo.central/howto/FvF.html
- Made simple sentence/grammatical corrections
Version: 3
Date: 2006-02-19
User Name: 97961
Action: Accept
Comment:
Version: 0

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