# US 2014/0207971 A1 · Method For Synchronising A Server Cluster And Server Cluster Implementing Said Method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0207971 A1 - Document ID: US20140207971A1 - Status: Published application - Kind: A1 - Application number: 14/241,059 - Filed: 2012-08-28 - Published: 2014-07-24 - Earliest claimed: 2011-08-30 - Assignees: Bull SAS - Inventors: Georges Lecourtier - Web page: https://patentgrep.com/patent/US20140207971A1 ## CPC - H04L 7/0079: {Receiver details} - G06F 1/10: Distribution of clock signals {, e.g. skew} - G06F 1/12: Synchronisation of different clock signals {provided by a plurality of clock generators} - H04J 3/0638: {Clock or time synchronisation among nodes; Internode synchronisation (synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43)} - H04L 7/0008: {Synchronisation information channels, e.g. clock distribution lines} - H04L 7/0337: {Selecting between two or more discretely delayed clocks or selecting between two or more discretely delayed received code signals} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract A method and system for synchronising a server cluster having a plurality of nodes each provided with an internal clock and interconnected with each other by a clock interconnection network comprising a plurality of transmission segments. Time stamping information is generated by the internal clock of a source chosen from the nodes of the server cluster. The time-stamping information is transmitted to all the nodes in the server cluster from the source; and the internal clock of each node of the server cluster is adjusted from this time-stamping information. The time for transmission of the time-stamping information is adjusted by each transmission segment to a constant value established for each transmission segment. Upon receiving the time-stamping information by any one of the nodes in the server cluster, its internal clock is adjusted from the time-stamping information and information relating to the transmission segments passed through between the source and this node. ## Claims ### Claim 1 A method for synchronising a server cluster comprising a plurality of nodes each provided with an internal clock and interconnected with each other by a clock interconnection network, said clock interconnection network comprising a plurality of transmission segments connecting the plurality of nodes together, the method comprising the following steps: generating time-stamping information by the internal clock of a source chosen from the plurality of nodes in the server cluster; transmitting, by the transmission segments of the clock interconnection network, of said time-stamping information to all nodes in the server cluster from the source; adjusting the internal clock of each said node in the server cluster using said time-stamping information; adjusting the time for transmitting time-stamping information by each transmission segment to a constant value established for each transmission segment; and upon receiving the time-stamping information by any one of the plurality of nodes in the server cluster, adjusting the internal clock of said node using the time-stamping information and information relating to the transmission segments passed through between the source and said node. ### Claim 2 (depends on 1) The method for synchronising a server cluster according to claim 1, wherein said adjusting the transmission time of any one of the transmission segments is performed using at least one delay line adjusted so as to align a phase of a signal carrying the time-stamping information to a phase of a reference signal internal to the plurality of nodes oscillating at a frequency corresponding to a common oscillation frequency of all the internal clocks of the plurality of nodes in the server cluster. ### Claim 3 (depends on 2) The method for synchronising a server cluster according to claim 2, wherein the transmission time of any one of the transmission segments is adjusted using two delay lines which are slaved according to a phase difference measured between a data frame supplied at an input of one of the two delay lines in a direction of transmission of the time-stamping information, and an echo of said data frame supplied at an output of the other one of the two delay lines in an opposite direction of transmission of the time-stamping information. ### Claim 4 (depends on 3) The method for synchronising a server cluster according to claim 3, wherein the slaving values of the two delay lines of any one of the transmission segments are further determined differently from each other according to a phase difference measured at an output of said transmission segment in the direction of transmission of the time-stamping information between a data frame supplied as an output of one of the two delay lines and a predetermined local phase reference. ### Claim 5 (depends on 1) The method for synchronising a server cluster according to claim 1, wherein a transmission time value established for each transmission segment is a same common maximum value established for all the transmission segments. ### Claim 6 (depends on 2) The method for synchronising a server cluster according to claim 2, wherein said same common maximum value established for all the transmission segments is obtained by an adjustment of the delay lines such that the phase of the signal carrying the time-stamping information is aligned on a rising or falling edges of the reference signal oscillating about an intermediate frequency. ### Claim 7 (depends on 5) The method for synchronising a server cluster according to claim 5, wherein the information relating to the transmission segments passed through between the source and any one of the plurality of nodes in the server cluster for transmitting the time-stamping information comprises a number of transmission segments passed through between the source and said one node. ### Claim 8 (depends on 1) The method for synchronising a server cluster according to claim 1, wherein a plurality of computing nodes are configured to execute application program instructions and operating system instructions, each said computing nodes being programmed to execute the operating system instructions in predetermined time windows, said executions in these predetermined time windows being triggered by the internal clock of each said computing node. ### Claim 9 (depends on 8) The method for synchronising a server cluster according to claim 8, wherein the predetermined time windows are the same for all the computing nodes. ### Claim 10 A server cluster comprising: a plurality of nodes each provided with an internal clock and interconnected with each other by a clock interconnection network, clock interconnection network comprising a plurality of transmission segments connecting the nodes together: a source chosen from said plurality of nodes in the server cluster, comprising means for generating time-stamping information using said internal clock of said source; means for the transmission, by the transmission segments of the clock interconnection network, of said time-stamping information to all the nodes in the server cluster from the source; means for adjusting the internal clock of each said node in the server cluster from said time-stamping information; and means for adjusting the time for transmitting the time-stamping information by each transmission segment to a constant value established for each transmission segment, wherein the internal clock adjustment means is designed to adjust the internal clock of each node in the server cluster using information relating to the transmission segments passed through between the source and this node. ### Claim 11 (depends on 10) The server cluster according to claim 10, wherein each node further comprises a chassis including in a computer rack included in a row of computer racks, the server cluster comprising a plurality of rows of computer racks, wherein the clock interconnection network comprises a plurality of segments interconnecting the rows together, segments for interconnecting together computer racks in the same row, segments for interconnecting together chassis in the same computer rack, and segments for interconnecting together nodes in the same chassis, and wherein said means for transmitting time-stamping information is configured to transmit to each node in the server cluster, having this time-stamping information, at least one item of information relating to a number of segments for interconnecting rows passed through between the source and the node, a number of computer rack interconnection segments passed through between the source and the node, and a number of chassis interconnection segments passed through between the source and the node. ### Claim 12 (depends on 11) The server cluster according to claim 11, wherein the information relating to the transmission segments passed through between the source and any one of the plurality of nodes in the server cluster comprises at least one field indicating a number of segment interconnecting rows passed through between the source and this node, a field indicating a number of segments interconnecting computer racks passed through between the source and the node and a field indicating a number of segments interconnecting chassis passed through between the source and this node, incrementation means is provided for incrementing each of these fields as soon as a corresponding segment is passed through by a message including the time-stamping information intended for this node. ### Claim 13 (depends on 10) The server cluster according to claim 10, further comprising: a first general administration network interconnecting all nodes together; and at least a second network managing computing data exchanged between the nodes, interconnecting at least some of the nodes together, wherein said clock interconnection network is a supplementary network, distinct from the first general administration network and the computing data management network. ### Claim 14 (depends on 14) The server cluster according to claim 14, wherein the computing data management network is a network implementing the HDLC protocol. ### Claim 15 (depends on 5) The method for synchronising a server cluster according to claim 5, wherein said same common maximum value established for all the transmission segments is obtained by an adjustment of the delay lines such that the phase of the signal carrying the time-stamping information is aligned on a rising or falling edge of the reference signal oscillating about an intermediate frequency. ### Claim 16 (depends on 15) The method for synchronising a server cluster according to claim 15, wherein said intermediate frequency is 1 MHz. ### Claim 17 (depends on 6) The method for synchronising a server cluster according to claim 6, wherein said intermediate frequency is 1 MHz.