High/low energy zone data storage
Methods and apparatus associated with storing data in high or low energy zones are described. Example apparatus include a data storage system (DSS) that protects a message using an erasure code (EC). A location in the DSS may have an energy efficiency rating or a latency. Example apparatus include logics that produce an EC that has a likelihood of use, that select a location to store the EC in the DSS based on the energy efficiency rating, the latency, or the likelihood of use, that store the EC in the location, and that compute an order of retrieval for an EC stored in the location. The order of retrieval may be based on the energy efficiency rating or the latency. The EC may also have a priority based on the number of erasures for which the EC corrects.
1. An apparatus for storing data, comprising:
a data storage system (DSS) that protects a message using an erasure code (EC), where a location in the DSS has an energy efficiency rating, and where the DSS is a hard disk drive (HDD) or a shingled magnetic recording (SMR) device that includes a platter that rotates, where the platter has an outer edge;
a processor;
a memory that stores electronic data that manages ECs for messages in the DSS;
a set of logics; and
an interface that connects the processor, the memory, the DSS, and the set of logics, the set of logics including:
an EC logic that produces an EC for a message present in the DSS, where the EC has a likelihood of use;
a storage logic that stores the EC in a location in the DSS, where the storage logic determines the energy efficiency rating of the location, and where the storage logic selects the location based, at least in part, on the energy efficiency rating of the location in the DSS or the likelihood of use of the EC; and
a retrieval logic that computes an order of retrieval, based, at least in part, on the energy efficiency rating of the location in the DSS or the likelihood of use of the EC, and where the retrieval logic retrieves the EC from the DSS based, at least in part, on the order of retrieval.
2. The apparatus of claim 1 , where the EC logic computes a priority for the EC, where the priority is based on a function of the number of erasures for which the EC corrects.
3. The apparatus of claim 2 , where the priority varies inversely with the number of erasures for which the EC corrects.
4. The apparatus of claim 2 , where the priority changes in response to a user configuration.
5. The apparatus of claim 2 , where the priority self-adapts based, at least in part, on a performance data associated with the DSS.
6. The apparatus of claim 5 , where the performance data describes a number of errors experienced by the DSS, a type of error experienced by the DSS, a frequency of errors experienced by the DSS, a cost of power used by the DSS, or a cost of network bandwidth used by the DSS.
7. The apparatus of claim 2 , where the priority is, additionally, based on a cost to store an EC on the DSS, a time to store an EC on the DSS, an amount of energy used to store an EC on the DSS, or a bandwidth required to store an EC on the DSS.
8. The apparatus of claim 2 , where the location has a latency rating, where the latency rating is based on a seek time of the DSS at the location, a rotation delay of the DSS at the location, an access time of the DSS at the location, or a transfer rate of the DSS at the location.
9. The apparatus of claim 8 , where the storage logic selects the location based, at least in part, on the energy efficiency rating, the latency rating, the likelihood of use, or the priority.
10. The apparatus of claim 9 , where the storage logic optimizes a utility measure based on the likelihood of use and the energy efficiency rating.
11. The apparatus of claim 2 , where the retrieval logic computes the order of retrieval based, at least in part, on the priority, the energy efficiency rating, or the likelihood of use.
12. The apparatus of claim 1 , where the energy efficiency rating varies inversely with a distance of the location in the DSS relative to the outer edge of the platter.
13. The apparatus of claim 1 , where the EC logic produces the EC by encoding the message using a systematic erasure code, a non-systematic erasure code, a Fountain code, a Reed-Solomon (RS) code, or a rate-compatible rateless code.
14. A non-transitory computer-readable storage medium storing computer executable instructions that when executed by a computer control the computer to perform a method for storing data in an energy efficient manner, the method comprising:
generating an encoded message, where the encoded message is generated using an erasure code (EC), where the encoded message has a storage priority based on a function of the number of erasures for which the EC corrects, and where the storage priority varies inversely with the number of erasures for which the EC corrects;
selecting a location in a data storage device (DSD) based, at least in part, on a direct relationship between an energy efficiency rating of the location and the storage priority;
writing the encoded message in the location, where the encoded message is written according to a write order based, at least in part, on the storage priority or the energy efficiency rating; and
reading the encoded message from the location, where the message is read according to a read order based, at least in part, on the storage priority.
15. The non-transitory computer-readable storage medium of claim 14 ,
where the location has a latency rating, where the latency rating is based on a seek time of the DSD at the location, a rotation delay of the DSD at the location, an access time of the DSD at the location, or a transfer rate of the DSD at the location,
the method comprising selecting a location in the DSD based, at least in part on a direct relationship between the energy efficiency rating and the storage priority, or an inverse relationship between the latency rating and the storage priority.
16. The non-transitory computer-readable storage medium of claim 15 , where the encoded message has an access probability, where the access probability is the probability that the encoded message will be accessed within a threshold period of time.
17. The non-transitory computer-readable storage medium of claim 16 , the method comprising selecting a location in the DSD based, at least in part, on a direct relationship between the energy efficiency rating and the access probability.
18. The non-transitory computer-readable storage medium of claim 16 , the method comprising selecting a location in the DSD based, at least in part, on an inverse relationship between the latency rating and the access probability or the storage priority.
19. The non-transitory computer-readable storage medium of claim 15 , the method comprising reading the encoded message from the location, where the message is read according to a read order, based, at least in part, on the storage priority, the energy efficiency rating, or the latency rating.
20. The non-transitory computer-readable storage medium of claim 14 , where the DSD is a disk drive that includes a platter that rotates, where the platter has an outer edge, where a first location is a first distance from the outer edge of the platter and has a first energy efficiency rating, and a second location is a second distance from the outer edge of the platter and has a second, different energy efficiency rating, where the first distance is less than the second distance, and where the first energy efficiency rating is greater than the second energy efficiency rating.
21. The non-transitory computer-readable storage medium of claim 14 , where the DSD includes a linear tape open (LTO) tape, where the LTO tape includes a set of zones, where a first zone includes a first location, where the first location has a first energy efficiency rating, and a second, different zone includes a second location, where the second location has a second energy efficiency rating, where the first energy efficiency rating is greater than the second energy efficiency rating.
22. A method for storing data, comprising:
accessing a message;
generating an encoded message by encoding the message using an erasure code, where the encoded message has a priority ranking;
determining an energy cost of storing the encoded message in a location on a data storage device;
selecting a location on the data storage device based, at least in part, on the priority ranking and the energy cost;
storing the encoded message in the location; and
retrieving the encoded message from the location in an order based, at least in part, on the priority ranking or the energy cost.