Patent Application
20170193013
The present disclosure relates to hard disk drives, and is particularly directed to a data storage space configuration of a hard disk drive and a method of configuring data storage space of a hard disk drive to limit seek distances during database metadata updates.
As a database system matures and available customer data storage capacity of a hard disk drive (HDD) is consumed, seek distances become larger during database metadata updates. This occurs in part due to physically-distant separation between database metadata storage space and customer data storage space. Certain metadata in some known database systems occupy a single contiguous region of a HDD. As the data storage capacity of the database system fills up, the seek distance the head of the HDD must travel to complete certain database update operations grows significantly. The increased seek distances not only increase mechanical wear on components of the HDD, but also impact performance of the database system due to longer seek times.
The effect of larger seek distances, and therefore larger seek times, is most acutely felt when the database metadata resides on the outer diameter of the HDD platter where transfer rates are highest. Placing database metadata on this “fast region” (outer diameter of the HDD platter) of the HDD is advantageous on immature systems since customer data is adjacent to the database metadata. As the database matures and additional customer data is loaded to the system, customer data will extend to the “medium region” (middle diameter of the HDD platter) and “slow region” (inner diameter of the HDD platter), where transfer rates are lower. This creates a situation where large seeks can occur during concurrent access of database metadata and customer data, which impacts overall system performance. This effect can be mitigated to some extent by moving the database metadata from the outer diameter of the HDD further into the middle diameter of the HDD (which reduces the maximum seek time by one-half and is often referred to as a “half seek”), but this often results in one of two problems.
One problem is that suboptimal scan performance can occur if the database system allocates its cylinders and extents (for customer data) from the middle diameter of the HDD to the outer diameter of the HDD. Suboptimal scan performance would result because the order of allocation by the database system would be “reversed” relative to progression of logical block addresses on the HDD. Alternatively, if the database system allocates its cylinders and extents (for customer data) from the outer diameter of the HDD to the inner diameter of the HDD, this results in the second problem: “half seeks” between customer data (at the outer diameter) and database metadata (at the middle diameter) on immature database systems that would otherwise have both database metadata and customer data in the “fast region” (i.e., the outer diameter) of the HDD.
It would be desirable to provide a data storage space configuration of a HDD and a method of configuring data storage space of a HDD to limit seek distances during database metadata updates, and to have resulting benefits apply to both immature (lightly filled) and mature (mostly full) databases.
In accordance with an embodiment, a data storage space configuration of a hard disk drive comprises a plurality of zones in which each one of the plurality of zones stores customer data. The data storage space configuration further comprises a plurality of database metadata storage spaces allocated in the plurality of zones, wherein the number of database metadata storage spaces is less than or equal to the number of zones. The database metadata may comprise temporary metadata. The database metadata may comprise write-ahead log (WAL) metadata. The database metadata may comprise staged-write (DEPOT) metadata for the purpose of interrupted write recovery.
In accordance with another embodiment, a method of configuring data storage space of a hard disk drive is provided. The method comprises electronically by a processor, defining a plurality of zones on the hard disk drive, electronically by a processor, storing customer data in each one of the plurality of zones, and electronically by a processor, allocating a plurality of database metadata storage spaces in the plurality of zones, wherein the number of metadata storage spaces is less than or equal to the number of zones. The database metadata may comprise temporary metadata. The database metadata may comprise write-ahead log (WAL) metadata. The database metadata may comprise staged-write (DEPOT) metadata for the purpose of interrupted write recovery. The method may be performed by a computer having a memory executing one or more programs of instructions which are tangibly embodied in a program storage medium readable by the computer.
In accordance with still another embodiment, a method of collocating customer data and database metadata on a hard disk drive is provided. The method comprises dividing data storage space of the hard disk drive into a plurality of zones, allocating a portion of the data storage space within each zone of the plurality of zone for storing customer data, and allocating a portion of the data storage space within a plurality of the plurality of zones for storing database metadata. The number of the plurality of the plurality of zones for storing database metadata may be less than the number of the plurality of zones. The number of the plurality of the plurality of zones for storing database metadata may be equal to the number of the plurality of zones. The database metadata may comprise temporary metadata. The database metadata may comprise write-ahead log (WAL) metadata. The database metadata may comprise staged-write (DEPOT) metadata for the purpose of interrupted write recovery. The method may be performed by a computer having a memory executing one or more programs of instructions which are tangibly embodied in a program storage medium readable by the computer.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures, in which
It is to be understood that the following disclosure provides many different embodiments or examples for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.
As shown in
In one implementation, the database metadata comprises temporary metadata, such as transactional metadata for example. Transactional metadata is associated with corresponding customer data for only a limited period of time. Once a transaction is sufficiently committed, the associated metadata for that transaction is deleted, and the HDD data storage space previously used for this metadata is re-purposed for new transactions. Accordingly, the association between transactional metadata and corresponding customer data has a limited lifetime.
In another implementation, the database metadata comprises write-ahead log (WAL) metadata (i.e., WAL-protected metadata updates). In yet another implementation, the database metadata comprises staged-write (DEPOT) metadata.
As shown in step 310 of
The above-described flowchart 300 of
It should be apparent that database metadata (e.g., WAL-protected metadata) is periodically set aside in separate zones throughout the addressable range of the entire HDD 200. HDD 200 could be thought of as being logically divided into many equal-size strata or zones. The number of zones is a user-configurable number. Within a zone, a percentage of the data storage capacity in that zone is allocated to storing database metadata, and the rest of the data storage space is allocated conventionally for storing customer data. The percentage of data storage capacity reserved for database metadata may be equal for some or all zones. Also, the percentage of data storage space in a zone may be contiguous within that zone, and may be user-configurable.
Updates to customer data cylinders within a zone results in use of database metadata cylinders within that same zone. In so doing, the seek distance associated with a write to database metadata and customer data is bounded to the distance associated with that particular zone. The greater the number of zones, the smaller each zone becomes, and therefore the shorter the seek distance between the database metadata and the customer data cylinders. For top recovery operations that require a re-read of database metadata, a reasonable cap/limit in the number zones (e.g., 1000 zones) can be enforced to avoid making database metadata reads too random and to avoid potential performance impact.
The above approach ensures that regardless of how mature a database system is (brand new, or nearly full), the seek distance incurred when performing database metadata updates (e.g., WAL-protected metadata updates) is somewhat fixed, and consistent over the life of the database system.
The above HDD solution collocates database metadata and customer data to limit seek distances during database metadata updates. This is accomplished by enabling the customer data in a zone to access corresponding database metadata stored in the same or nearby zone.
The above-described configuration of data storage space for HDD 200 is user-definable and customizable to fit a particular environment. User-defined configurations are externalized to provide a flexible and customizable data storage space solution for a HDD. This is opposite to using a single configuration which is a “one size fits all” type of approach.
The above-described HDD solution can support a number of different scenarios. For example, HDD 200 can support a scenario in which WAL-protected metadata is used. In another example, HDD 200 can support a scenario in which DEPOT metadata is used.
Although the above description describes a TVS architecture supporting HDD 200, it is conceivable that the same concept can be applied to support a wide variety of other types of architectures.
The illustrative diagrams and flowcharts depict process steps or diagrams that may represent modules, segments, or portions of code that include one or more executable instructions for implementing specific logical functions or steps in the process. Although the particular examples illustrate specific process steps or procedures, many alternative implementations are possible and may be made by simple design choice. Some process steps may be executed in different order from the specific description herein based on, for example, considerations of function, purpose, conformance to standard, legacy structure, user interface design, and the like.
Aspects of the disclosed embodiments may be implemented in software, hardware, firmware, or a combination thereof. The various elements, either individually or in combination, may be implemented as a computer program product tangibly embodied in a machine-readable storage device for execution by a processing unit. Various steps of embodiments may be performed by a computer processor executing a program tangibly embodied on a computer-readable medium to perform functions by operating on input and generating output. The computer-readable medium may be, for example, a memory, a transportable medium such as a compact disk, a floppy disk, or a diskette, such that a computer program embodying aspects of the disclosed embodiments can be loaded onto a computer.
The computer program is not limited to any particular embodiment, and may, for example, be implemented in an operating system, application program, foreground or background process, or any combination thereof, executing on a single processor or multiple processors. Additionally, various steps of embodiments may provide one or more data structures generated, produced, received, or otherwise implemented on a computer-readable medium, such as a memory.
Still further, although depicted in a particular manner, a greater or lesser number of modules and connections can be utilized with the present disclosure in order to accomplish embodiments, to provide additional known features to present embodiments, and/or to make disclosed embodiments more efficient. Also, the information sent between various modules can be sent between the modules via at least one of a data network, an Internet Protocol network, a wireless source, and a wired source and via a plurality of protocols. Many other embodiments are also within the scope of the following claims.
This application claims priority under 35 U.S.C. §119(e) to the following co-pending and commonly-assigned patent application, which is incorporated herein by reference: Provisional Patent Application Ser. No. 62/273,812, entitled “DATA STORAGE SPACE CONFIGURATION OF A HARD DISK DRIVE AND METHOD OF CONFIGURING DATA STORAGE SPACE OF A HARD DRIVE TO LIMIT SEEK DISTANCES DURING DATABASE METADATA UPDATES,” filed on Dec. 31, 2015, by Matthew James Fischer.
| Number | Date | Country | |
|---|---|---|---|
| 62273812 | Dec 2015 | US |
