FIELD

This technology generally relates to data storage networks and, more particularly, to methods and devices for cache rewarming in a failover domain within a data storage network.

BACKGROUND

In many data storage networks, storage nodes (e.g., controllers or filers) share data storage devices in a cluster or array that may be hosted by a shelf or other enclosure. The storage nodes may be cooperating to provide high availability or other storage services for the storage network. As one particular example, the storage nodes may be a high availability (HA) pair of storage nodes in a failure domain that utilize an array of data storage devices hosted by one or more shelves in a Fibre-attached storage (FAS) architecture.

In order to improve performance, storage nodes can include a cache that can be hosted on non-volatile memory, such as flash memory. The cache can be populated by data that is read from the data storage devices of the storage array and has an increased likelihood of being accessed again by clients relatively soon. In a subsequent access request for the data, the data can advantageously be served from the local, high performance, low latency cache, thereby improving storage network performance.

Cache storage is generally owned by a single storage node, but the cache contents are maintained in a non-volatile memory and can be used by the storage node following a failure event through a process referred to as cache rewarming. Since the cache contents are not accessible during the failure event, some of the data may be stale or cold upon reboot of the storage node.

However, a partner or takeover node (e.g., in an HA pair) can keep track of data modifications (e.g., overwrites or invalidations) during the failure event, which can be replayed by the failed storage node upon reboot in order to rewarm the cache. Unfortunately, since the cache is not utilized or accessible to the takeover node during the failure event, the storage network experiences degraded performance and increased latency during the failure event and until the failed storage node comes back online and rewarms the cache.

