Non-disruptive upgrade of storage appliance nodes using host initiator login information to avoid data unavailability

A system comprising:

• one or more processors;
• and
• a memory comprising code stored thereon that, when executed, performs a method of performing a non-disruptive upgrade of nodes of a storage appliance, the nodes including a first portion of the nodes and a second portion of the nodes, the method comprising:
• recording an initial set of host initiator login information identifying which of a plurality of host initiators are logged into which nodes of the storage appliance prior to performing the non-disruptive upgrade to upgrade the nodes from a current software version to a target software version;
• installing the target software version on the first portion of the nodes of the storage appliance;
• restarting the first portion of the nodes of the storage appliance running the target software version while also running the current software version on the second portion of the nodes of the storage appliance, wherein the non-disruptive upgrade is performed to upgrade the nodes of the storage appliance from the current software version to the target software version;
• subsequent to installing the target software version and said restarting, while the first portion of the nodes of the storage appliance are running the target software version and while the second portion of the nodes are running the current software version, performing I/O (input/output) operation forwarding so that I/O operations from the plurality of host initiators are serviced using the second portion of the nodes and not serviced using the first portion of the nodes, wherein, during said I/O operation, forwarding one or more of the plurality of host initiators are logged into at least one node of the first portion of the nodes and at least one node of the second portion of the nodes, and wherein said I/O operation forwarding includes the first portion of the nodes that receives the I/O internally forwarding the I/O operations within the storage appliance from the first portion of the nodes to the second portion of the nodes for servicing by the second portion of the nodes using the current software version, and wherein the I/O operations are serviced using the current software version running on the second portion of the nodes;
• recording a second set of the host initiator login information while performing the I/O operation forwarding, said second set of the host initiator login information identifying which of the plurality of host initiators have re-logged into which nodes of the first portion;
• comparing the initial set and the second set to determine whether there are any inconsistencies between the initial set and the second set;
• and
• determining, in accordance with the host initiator login information and while said I/O operation forwarding is performed that internally forwards the I/O operations, whether to continue with the non-disruptive upgrade of the nodes by upgrading the second portion of the nodes to the target software version.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method of a non-disruptive upgrade of nodes of a storage appliance, the nodes including a first portion of the nodes and a second portion of the nodes, the method comprising:

• recording an initial set of host initiator login information identifying which of a plurality of host initiators are logged into which nodes of the storage appliance prior to performing the non-disruptive upgrade to upgrade the nodes from a current software version to a target software version;
• installing the target software version on first portion of the nodes of the storage appliance;
• restarting the first portion of the nodes of the storage appliance running the target software version while also running the current software version on the second portion of the nodes of the storage appliance, wherein the non-disruptive upgrade is performed to upgrade the nodes of the storage appliance from the current software version to the target software version;
• subsequent to installing the target software version and said restarting, while the first portion of the nodes of the storage appliance are running the target software version and while the second portion of the nodes are running the current software version, performing I/O (input/output) operation forwarding so that I/O operations from the plurality of host initiators are serviced using the second portion of the nodes and not serviced using the first portion of the nodes, wherein, during said I/O operation forwarding, one or more of the plurality of host initiators are logged into at least one node of the first portion of the nodes and at least one node of the second portion of the nodes, and wherein said I/O operation forwarding includes the first portion of the nodes that receives the I/O operations internally forwarding the I/O operations within the storage appliance from the first portion of the nodes to the second portion of the nodes for servicing by the second portion of the nodes using the current software version, and wherein the I/O operations are serviced using the current software version running on the second portion of the nodes;
• recording a second set of the host initiator login information while performing the I/O operation forwarding, said second set of the host initiator login information identifying which of the plurality of host initiators have re-logged into which nodes of the first portion;
• comparing the initial set and the second set to determine whether there are any inconsistencies between the initial set and the second set;
• and
• determining, in accordance with the host initiator login information and while said I/O operation forwarding is performed that internally forwards the I/O, whether to continue with the non-disruptive upgrade of the nodes by upgrading the second portion of the nodes to the target software version.