Netapp, Inc.

Melvin McGee

Wayne A Booth

Mayank Saxena

Technology is disclosed for recovering I/O modules in a storage system using in-band alternate control path (ACP) architecture ('the technology'). The technology enables a storage server to transmit control commands, e.g., for recovering an I/O module, to the I/O module over a data path that is typically used to transmit data commands. The control commands are typically transmitted using ACP that is separate from the data path. By enabling transmission of control commands over the data path, the technology eliminates the need for separate medium for ACP, at least in part, to transmit the control commands. The technology can be implemented in a pure in-band ACP mode, which supports recovering an I/O module of a storage shelf in which at least one I/O module is responsive, and/or in a mixed in-band ACP mode, which supports recovery of I/O modules of a storage shelf in which all I/O modules are non-responsive.

In-band recovery mechanism for I/O modules in a data storage system

A system and method are provided for counting storage-related error events using a sliding window. This is accomplished by counting error events that occur within a sliding window of time and triggering a reaction based on such count. By this feature, the error events are counted with additional accuracy so that a reaction will be appropriately triggered. To this end, in various embodiments, more accurate error counting is afforded to avoid a situation, such as in fixed sampling window frameworks, where an appropriate reaction is not triggered due to a failure to count an appropriate number error events in close proximity.

System and method for counting storage device-related errors utilizing a sliding window

Method and system is provided where PHY state change (PHY CHANGE) notifications from one or more PHYs in a storage infrastructure are monitored as a potential error condition. The rate of PHY CHANGE notifications is monitored to determine if the rate of PHY CHANGE notifications may cause a loss of service or degrade I/O performance. An excessive rate of PHY CHANGE notification that may cause a loss of service is detected by comparing a current PHY CHANGE count with a burst threshold value. The current PHY CHANGE count is also compared to an operational threshold value to detect if the rate of PHY CHANGE notification may result in degradation of overall I/O performance. If the PHY CHANGE count for a PHY equals or exceeds the burst threshold value or the operational threshold value, then the PHY is disabled.

Method and system for minimizing unnecessary topology discovery operations by managing physical layer state change notifications in storage systems

Method and system is provided where PHY state change (PHY CHANGE) notifications from one or more PHYs in a storage infrastructure are monitored as a potential error condition. The rate of PHY CHANGE notifications is monitored to determine if the rate of PHY CHANGE notifications may cause a loss of service or degrade I/O performance. An excessive rate of PHY CHANGE notification that may cause a loss of service is detected by comparing a current PHY CHANGE count with burst threshold value. The current PHY CHANGE count is also compared to an operational threshold value to detect if the rate of PHY CHANGE notification may result in degradation of overall I/O performance. If the PHY CHANGE count for a PHY equals or exceeds the burst threshold value or the operational threshold value, then the PHY is disabled.

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Sunnyvale, CA, United States of America

Melvin McGee