Patent Application
20080077742
One form of storage data buffer flushing events are events related, directly or indirectly, to one or more buffer flushing parameters, such as, for example, a storage data object quantity threshold indicative of a quantity trigger for flushing storage data buffer 21 or a buffered byte quantity threshold indicative of another quantity trigger for flushing storage data buffer 21. Another form of storage data buffer flushing events are events related, directly or indirectly, to an operational status of host 50, storage drive control unit 20, storage drive 30 and/or storage medium 40, such as for example, a volume end event of storage medium 40 or a data object processing error event indicative of an occurrence of specific error conditions.
To further understand the inventive principles of the present invention,
Specifically, a stage S102 of flowchart 100 encompasses host 60 initiating a processing of a host data object HDO buffered in host data buffer 81 as known in the art whereby the processing of the host data object HDO includes writing a storage data object SDO corresponding to host data object HDO to storage data buffer 21. As part of processing host data object HDO, host 60 determines whether a storage data buffer flushing event has occurred for purposes of determining whether to flush storage data objects SDO buffered within storage data buffer 21 prior to or subsequent to (i.e., relative to) writing the storage data object SDO corresponding to the host data object HDO to the storage data buffer 21. In one exemplary embodiment, host 60 determines an occurrence of a storage data buffer flushing event upon a quantity of storage data objects SDO buffered within storage data buffer 21 equaling a storage data object quantity threshold (i.e., a predetermined quantity of storage data objects SDO stored within storage data buffer 21 for triggering a flushing of storage data buffer 21). In another exemplary embodiment, host 60 determines an occurrence of a storage data buffer flushing event upon a buffered data byte quantity exceeding a buffered data byte quantity threshold (i.e., a predetermined number of cumulative megabytes of storage data objects SDO buffered by storage data buffer 21 for triggering a flushing of storage data buffer 21).
The determination outcome of stage S104 is essential for host 60 in commanding whether the next flushing of storage data buffer 21 is inclusive of or exclusive of the storage object data SDO corresponding to the host data object HDO of stage S102. For example, as shown in
Conversely, storage data objects SDO1 and SDO2 will be flushed from storage data buffer 21 to storage medium 40 during a stage S108 of flowchart 100 prior to storage data object SDO3 being written to storage data buffer 21 during stage S106 if host 60 determines a storage data buffer flushing event occurred during stage S 104. The occurrence determination of stage S104 may involve the storage data object quantity threshold being two data objects in view of two storage data objects SDO1 and SDO2 and/or the buffered data byte quantity threshold being three megabytes in view of three megabytes of storage data objects SDO1 and SDO2 to storage medium 40.
By further example, assume a storage data buffer flushing event did not occur during S104 as related to the processing of host data object HDO3. In view of a buffering of storage data objects SDO1, SDO2 and SDO3 within storage data buffer 21 and a host data object HDO4 of four megabytes being selected for processing during stage S102, storage data object SDO4 corresponding to host data object HDO4 will be written to storage data buffer 21 during stage S106 prior to buffered storage data objects SDO1-SDO3 being flushed from storage data buffer 21 to storage medium 40 if host 60 determines a storage data buffer flushing event has not occurred during stage S104. The occurrence determination of stage S104 may involve a storage data object quantity threshold being four data objects in view of three storage data objects SDO1-SDO3 and/or a buffered data byte quantity threshold being ten megabytes in view of six megabytes of storage data objects SDO1-SDO3. As a result, storage data object SDO4 will be included with storage data objects SDO1-SDO3 during the next future deterministic flushing of storage data buffer 21 to storage medium 40.
Conversely, storage data objects SDO1-SDO3 will be flushed from storage data buffer 21 to storage medium 40 during stage S108 prior to storage data object SDO4 being written to storage data buffer 21 during stage S106 if host 60 determines a storage data buffer flushing event occurred during stage S104. The occurrence determination of stage S104 may involve a storage data object quantity threshold being three data objects in view of three storage data objects SDO1-SDO3 and/or a buffered data byte quantity threshold being six megabytes in view of six megabytes of storage data objects SDO1-SDO3.
Of additional importance is an asynchronous updating of meta-data associated with each host data object HDO selected for processing during stage S102. Specifically, host 60 will queue a meta-data update of a processed host data object in queue 82 in accordance with stage S106 for each determination during stage S104 that a storage data buffer flushing event has not occurred and will initiate a processing of all queued meta-data updates during stage S108 only upon a determination during stage S104 that a storage data buffer flushing event has occurred. Those having ordinary skill in the art will appreciate that this queuing and asynchronous processing of meta-data updates until an occurrence of a storage data buffer flushing event enhances the flushing productivity of host 50.
In practice, the present invention does not impose any limitations or any restrictions to the manner by which flowchart 100 is implemented. Thus, the following description of an exemplary embodiment of flowchart 100 as illustrated in
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Otherwise, host 60 proceeds to a stage S116 of flowchart 110 to determine if a buffered data byte quantity (“BDBQ”) exceeds a buffered data byte quantity threshold (“BDBQT”). If so, then host 60 sequentially proceeds to stage S126 to flush storage data objects SDO1 and SDO2 buffered within storage data buffer 21 to storage medium 40, stage S128 to initiate a processing of the queued meta-data updates associated with host data objects HDO1 and HDO2, stage S122 to write storage data object SDO3 to flushed storage data buffer 21 and stage S124 to queue the meta-data update associated with host data object HDO3.
Otherwise, host 60 proceeds to a stage S118 of flowchart 110 to detect if a natural end of volume (“NEOV”) event of storage medium 40 or a forced end of volume (“FEOV”) event of storage medium 40 has occurred. If so, then host 60 sequentially proceeds to stage S126 to flush storage data objects SDO1 and SDO2 buffered within storage data buffer 21 to storage medium 40, stage S128 to initiate a processing of the queued meta-data updates associated with host data objects HDO 1 and HDO2, stage S122 to write storage data object SDO3 to flushed storage data buffer 21 and stage S124 to queue the meta-data update associated with host data object HDO3.
Otherwise, host 60 proceeds to a stage S120 of flowchart 110 to detect if a system error condition has occurred. If so, then host 60 sequentially proceeds to stage S126 to flush storage data objects SDO1 and SDO2 buffered within storage data buffer 21 to storage medium 40, stage S128 to initiate a processing of the queued meta-data updates associated with host data objects HDO1 and HDO2, stage S122 to write storage data object SDO3 to flushed storage data buffer 21 and stage S124 to queue the meta-data update associated with host data object HDO3.
Otherwise, host 60 sequentially proceeds to stage S122 to write storage data object SDO3 to unflushed storage data buffer 21 and stage S124 to queue the meta-data update associated with host data object HDO3. As such, upon the next future flushing of storage data buffer 21 during stage S126, storage data object SDO3 will be flushed with storage data objects SDO1 and SDO2 along with any other additional storage data objects written to storage data buffer 21 prior to such a flushing of storage data buffer 21. Furthermore, the queued meta-data update associated with host data object HDO3 will be processed with queued meta-data updates associated with host data objects HDO1 and HDO2 along with any other queued meta-data updates prior to such a flushing of storage data buffer 21.
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Furthermore, those having ordinary skill in the art of buffer flushing techniques may develop other embodiments of the present invention in view of the inventive principles of the present invention described herein. Thus, the terms and expression which have been employed in the foregoing specification are used herein as terms of description and not of limitations, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the present invention is defined and limited only by the claims which follow.
