Techniques for log ordering to optimize write latency in systems assigning logical address ownership

A system comprising:

• one or more processors;
• and
• a memory comprising code stored thereon that, when executed, performs a method comprising:
• receiving a first command at a first node in a system, wherein the system further includes a second node, wherein the first node manages a first set of user data (UD) log resources including a first structure of page descriptors (PDESCs) and second structure of page blocks (PBs), wherein the second node manages a second set of UD log resources including a third structure of PDESCs and a fourth structure of PBs, wherein the first node generates sequence numbers from a first node-local sequence SEQ1 of monotonically increasing integer values greater than zero, where the second node generates sequence number from a second node-local sequence SEQ2 of monotonically increasing integer values greater than zero, wherein a UD log includes the first set of UD log resources and the second set of UD log resources, wherein each command, operation or request recorded in the UD log is associated with a unique corresponding generic serial number (GENSN) that includes a first field F1 with a value corresponding to the first node for the recorded command, operation or request, and that includes a second field F2 with a value corresponding to the second node for the recorded command, operation or request;
• determining whether the first command is a first write I/O directed to first one or more logical addresses owned exclusively by the first node that received the first command;
• and
• responsive to determining the first command is a first write I/O directed to first one or more logical addresses owned exclusively by the first node, performing first processing by the first node to record the first write I/O in the UD log without any internode communication with the second node, the first processing performed by the first node including:
• generating a first GENSN uniquely identifying the first write I/O, wherein the first GENSN includes a first sequence number SN1 allocated from SEQ1 in F1 and includes a zero value in F2;
• and
• recording the first write I/O in the UD log including:
• storing a first PDESC of the first structure of PDESCs of the first set of UD log resources managed by the first node, wherein the first PDSEC describes the first write I/O, wherein the first PDESC includes the first GENSN uniquely identifying the first write I/O recorded in the UD log.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method comprising:

• receiving a first command at a first node in a system, wherein the system further includes a second node, wherein the first node manages a first set of user data (UD) log resources including a first structure of page descriptors (PDESCs) and second structure of page blocks (PBs), wherein the second node manages a second set of UD log resources including a third structure of PDESCs and a fourth structure of PBs, wherein the first node generates sequence numbers from a first node-local sequence SEQ1 of monotonically increasing integer values greater than zero, where the second node generates sequence number from a second node-local sequence SEQ2 of monotonically increasing integer values greater than zero, wherein a UD log includes the first set of UD log resources and the second set of UD log resources, wherein each command, operation or request recorded in the UD log is associated with a unique corresponding generic serial number (GENSN) that includes a first field F1 with a value corresponding to the first node for the recorded command, operation or request, and that includes a second field F2 with a value corresponding to the second node for the recorded command, operation or request;
• determining whether the first command is a first write I/O directed to first one or more logical addresses owned exclusively by the first node that received the first command;
• and
• responsive to determining the first command is a first write I/O directed to first one or more logical addresses owned exclusively by the first node, performing first processing by the first node to record the first write I/O in the UD log without any internode communication with the second node, the first processing performed by the first node including:
• generating a first GENSN uniquely identifying the first write I/O, wherein the first GENSN includes a first sequence number SN1 allocated from SEQ1 in F1 and includes a zero value in F2;
• and
• recording the first write I/O in the UD log including:
• storing a first PDESC of the first structure of PDESCs of the first set of UD log resources managed by the first node, wherein the first PDSEC describes the first write I/O, wherein the first PDESC includes the first GENSN uniquely identifying the first write I/O recorded in the UD log.