摘要:
A method and apparatus are provided for implementing command queue ordering with benefit determination of a prefetch operation. For each command in a hard disk drive command queue, a rotational position optimization (RPO) score is calculated. A prefetch benefit is calculated for each command in the hard disk drive command queue within a working partition. The RPO score is modified utilizing the calculated prefetch benefit for the commands in the hard disk drive command queue within the working partition. A best RPO score is identified to select a next command in the hard disk drive command queue to execute.
摘要:
An adaptive maximum seek velocity clipping technique is employed in a disk drive to reduce head movement power requirements. Separate maximum seek velocities are established for respective categories of access commands, where the categories are defined by seek distance and estimated extra latency. The maximum seek velocity established for each category of access commands reflects actual experience in executing access commands of the given category. The maximum seek velocity values for the various categories are stored in a maximum seek velocity table, which is referred to upon execution of access commands. The inventive power-saving technique may be advantageously applied in conjunction with a probability-based shortest access time first (SATF) command queue ordering algorithm.
摘要:
Techniques for improved copy on write functionality within an SSD are disclosed. In some embodiments, the techniques may be realized as a method for providing improved copy on write functionality within an SSD including providing, in memory of a device, an indirection data structure. The data structure may include a master entry for cloned data, the master entry having a reference to one or more indexes and a clone entry for the cloned data, the cloned entry having at least one of: a reference to a master index, a reference to a next index, and a value indicating an end of a data structure. The techniques may include traversing, using a computer processor, one or more copies of the cloned data using one or more of the references.
摘要:
Techniques for improved copy on write functionality within an SSD are disclosed. In some embodiments, the techniques may be realized as a method for providing improved copy on write functionality within an SSD including providing, in memory of a device, an indirection data structure. The data structure may include a master entry for cloned data, the master entry having a reference to one or more indexes and a clone entry for the cloned data, the cloned entry having at least one of: a reference to a master index, a reference to a next index, and a value indicating an end of a data structure. The techniques may include traversing, using a computer processor, one or more copies of the cloned data using one or more of the references.
摘要:
A method and apparatus are provided for implementing secure erase for solid state drives (SSDs). An encryption key is used to encrypt data being written to SSD. A controller identifies a key storage option, and responsive to the identified key storage option, stores a key for data encryption and decryption. The controller deletes the key within the SSD responsive to the identified key storage option, ensuring that once the key is deleted, the key is not recoverable and data is effectively erased.
摘要:
A method and apparatus are provided for implementing secure erase for solid state drives (SSDs). An encryption key is used to encrypt data being written to SSD. A controller identifies a key storage option, and responsive to the identified key storage option, stores a key for data encryption and decryption. The controller deletes the key within the SSD responsive to the identified key storage option, ensuring that once the key is deleted, the key is not recoverable and data is effectively erased.
摘要:
Multiple disk access commands such as XOR commands are broken down into their constituent read and write parts and, if in LBA sequence, coalesced into pipes. These XOR read and write commands are then provided to the RPO algorithm of the HDD for scheduling along with data reads and writes. The actual XOR buffer operation is also scheduled by the RPO algorithm, advantageously to occur during a seek for another read or write.
摘要:
An RPO algorithm in a HDD coalesces LBA-sequential XOR commands in pipes, and passes the pipes to a lower level execution engine. The execution engine executes XOR reads and write separately to optimize performance using head and/or cylinder skew information to approach the nominal disk data rate.
摘要:
A method and apparatus is provided which reduces the equipment and time requirements for hard disk drive performance testing during manufacturing. This invention executes self-contained performance testing code that resides within the drive's manufacturing firmware, rather than relying on external testers. The invention involves exercising the drive's enqueue, dequeue, and command execution firmware, as well as the physical process of reading and writing data by simulating the host interface in code. The invention enqueues commands that typify the desired workload, allows a command ordering algorithm to sort the commands for execution, and allows the drive side code to execute the commands just as if an external host interface were attached. The invention is advantageous because the performance testing can be done by only applying power to the drive. The present invention also lends itself to performance tuning that can be done in manufacturing, to reduce drive-to-drive performance variations.
摘要:
A method and apparatus are provided for hard disk drive command queue ordering. For each command in the hard disk drive command queue, an expected access time is calculated including a probability of success calculation. A command in the hard disk drive command queue having a minimum calculated expected access time is identified. Then the identified command having a minimum calculated expected access time is executed. For an estimated seek time of less than a time for one full revolution, a probability of a miss multiplied by a time of one extra revolution is calculated and the result is added to an estimated seek time to provide the expected access time. For an estimated seek time of greater than a time for one full revolution, a probability of a make multiplied by a time of one extra revolution is calculated and the result is subtracted from an estimated seek time to provide the expected access time.