| 摘要 |
Non-volatile random access memory (NVRAM) caching and logging may be configured to deliver low latency acknowledgements of input/output (I/O) requests, such as write requests, while avoiding loss of data associated with the requests that may occur as a result of power failures. Write data associated with one or more write requests may be received at a node of a cluster. The write data may be stored in a portion of an NVRAM configured as, e.g., a persistent write-back cache of the node, while parameters of the request may be stored in another portion of the NVRAM configured as one or more logs, e.g., NVLogs. The write data may be organized into separate variable length blocks or extents and "written back" out-of-order from the write back cache to storage devices, such as solid state drives (SSDs). The write data may be preserved in the write-back cache until each extent is safely and successfully stored on SSD (i.e., in the event of power loss), or operations associated with the write request are sufficiently logged on NVLog, to thereby provide efficient recovery when attempting to restore the write data preserved in the cache to the SSDs. |
