Sun System Handbook - ISO 3.4 June 2011 Internal/Partner Edition | |||
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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. --- "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 Attachments This solution has no attachment |
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