Automatic mapping and efficient address translation for multi-surface, multi-zone storage devices

[0002] The present invention relates to large capacity data storage devices. More specifically, the present invention relates to a system and method for automatic mapping and address translation for data storage systems having multi-surface, multi-zone storage devices.

[0003] Today's computers have many different data storage needs. These needs can be satisfied by a large number of storage devices such as disk storage systems, hard drivers, tape storage systems, etc. These systems communicate with the host computer and manage the actual data storage task. Typically, data is transferred to and from the storage devices as a contiguous stream of logical blocks, wherein each block has a unique logical block address (LBA). This information, identified by the logical block address, must then be stored at some physical location in the data storage device.

[0004] In the case of a disk storage device, the storage area is arranged in surface-track-sector addresses (STSA). Each LBA referred to by the host computer must be mapped to a unique STSA on the storage device in order to accommodate easy identification and retrieval. As a further complication to this mapping requirement, the storage devices will often employ multiple surfaces, and multiple zones on the storage media. Efficient use of these multiple surfaces and zones must be considered when devising the mapping and subsequent translations methodology.

[0005] Once a data storage and retrieval methodology is established, it is extremely difficult to make adjustments. If a new disk configuration is introduced, the established mapping methodology must be reworked. As would be expected a new configuration requires the development of new address mapping and translation formulations, including further testing and validation.

[0006] When using storage devices with multiple surfaces, it is often beneficial to read data from or write data to both sides of the disk simultaneously. This helps to increase the overall data rate of the storage device. However, this complicates the mapping and data storage methodologies. Specifically, the data storage methodology is much more complicated because two read/write heads must be continually utilized, and the addressing must be maintained for both those surfaces.

[0007] As mentioned above, certain data storage devices have multiple zones on a surface thereof. Each zone is typically an area on the surface wherein each track within the zone has similar characteristics. More specifically, a zone is typically identified as a group of tracks which all have the same number of sectors on each track. For example, a disk may be broken into four different zones wherein the tracks in the first zone have two sectors per track, the second zone have four sectors per track, the third zone have six sectors per track, and the last zone have eight sectors per track. The number of zones contained on a disk, and the number of sectors per track within that zone will depend upon the physical set up and configuration of the disk, as dictated by the manufacturer.

[0008] In order to solve the mapping problems, prior systems have utilized a “hardcoded” algorithm. That is, the data was mapped to the disk using a predetermined set of instructions for the particular disk configuration. While this solution was efficient, it was not capable of providing for varying disk configurations. For example, if the number of sectors per track in a given zone changed, or the number of tracks changed, the code had to be rewritten. This is an undesired activity as it is extremely costly and time consuming.

[0009] In order to maintain effective data transfer rates using a data storage device with multiple surfaces and multiple zones, and to automatically react to changes in the disk configuration, the present invention provides an automated mapping technique and system for a general STSA configuration. In order to map from an LBA to an STSA, a configuration table (CT) is used which specifies the physical configuration of the storage device. This configuration table is utilized to automatically generate address translation formulations. Consequently, a modification of the disk configuration for the particular storage device, will result in a modified configuration table. This will then automatically change the address translation formulation.

[0010] An address translation structure, is used to accommodate efficient address translation formulations. This address translation structure utilizes a Physical Block Address (PBA) as an intermediate tool in the translation. Utilizing the above mentioned configuration table, the physical block address is correlated to each available sector on the disk. This PBA helps to simplify the address translation formulations.

[0011] As a starting point, information about the disk layout is input by the user. This includes providing range definitions for the disk surfaces which identifies those areas available for user data storages, and those areas designated for other purposes. Collection of all range definitions is assembled in the configuration table which identifies the layout of the disk. Specifically, the configuration table will identify which tracks on the disk are available for user data storage and which tracks are not. Also, the user will provide the number of sectors per track in the particular zones, and any desired pairing information. Based on this information, an address translation structure is developed. This address translation structure, along with appropriate translation formulas, will then allow fast and efficient address mapping.

[0012] As the host computer provides directions regarding data storage and retrieval, the address translation structure provides a useful mechanism for accomplishing the necessary mapping. When information is provided by host computer and identified by a logical block address (LBA), this information will be assigned and stored at one or more sectors, each sector identified by a physical block address. The LBA and its associated physical block addresses are easily calculated using the address translation structure and associated formulas. These formulations allow for easy retrieval and identification of stored information.

[0013] As can be easily recognized, this methodology allows the disk configuration to be easily modified, without detrimentally affecting the remainder of the addressing scheme. More specifically, a change in the disk configuration, will show up as a change to the configuration table. Since all other mapping steps are dependent upon the configuration table, changing its contents will automatically change the steps and information used by the remainder of the addressing scheme. Consequently, these additional changes are automatically passed down.

[0014] It is an object of the present invention to provide an address mapping and translation system which can easily and quickly react to changes in the disk configuration. Consequently, various disk configurations can easily be changed without requiring large amounts of reprogramming.

[0015] It is a further object of the present invention to provide an address mapping and translation system which utilizes an easily modifiable configuration table. The configuration table itself defines the various ranges and configurations for the disk itself.

[0016] It is a further object of the present invention to provide a data mapping system which easily converts a logical block address, provided by a host computer, to a surface-track-sector address. This surface-track-sector address identifying a specific data sector on the data storage media.

[0017] Further objects and advantages of the present invention can be seen by reviewing the following detailed description in conjunction with the drawings in which:

[0018] FIG. 1 is a schematic drawing illustrating the disk storage system and host computer;

[0019] FIG. 2 is a flow chart illustrating the data storage methodology more specifically includes an easily altered configuration table; and

[0020] FIG. 3 is a graphical illustration of portions of an exemplary configuration table;

[0021] The disk system of the present invention easily reacts to changes in the disk configuration by maintaining a configuration table (CT) which defines the layout of the disk. This configuration table is input by the user, based on information provided by the disk manufacturer and the chosen disk set-up. This configuration table is then utilized for all further mapping and translation operations. Consequently, the disk system easily reacts to changes in this configuration table by automatically adjusting its mapping process and methodology.

[0022] Referring now to FIG. 1, there is shown a schematic diagram of the disk storage system 10 which must appropriately perform the necessary mapping and translations. Obviously, disk storage system 10 receives requests from host computer 60. One core component of storage system 10 is an optical media 12. Optical media 12 could include an optical disk, however is not necessarily limited to that type of storage media. Disk storage system 10, necessarily has a read/write head 34 incorporated therein for writing data to the optical media 12 as well as reading data therefrom. In the embodiment shown, both a first read/write head 34 and a second read/write head 36 are necessary as two sides of optical media 12 are being used. Disk storage system 10 further includes drive electronics 16 for operating the functions of the drive. Also associated is a drive controller 20 which includes a memory or RAM 24. Interacting with the output from first read/write head 34 is a first read/write channel 26 which necessarily includes an internal decoder (now shown). First read/write channel 26 provides a data path from media 12 to controller 20. Similarly, a second read/write channel 28 is provided for transferring data from second read/write head 36 to controller 20. By operating both first read/write channel 26 and second read/write channel 28, data can simultaneously be read from both sides of the disk, and provided to controller 20.

[0023] It will be understood that many variations could be incorporated into this component hardware. Also, various functions may be undertaken by controller 20 or may be controlled by other components, such as drive electronics 16. As seen in FIG. 1, controller 20 can be in communication with many other devices via host interface 22.

[0024] First read/write head 34 and second read/write head 36 includes various components which efficiently accommodate their operation. Specifically, a first read/write actuator 30 is included for accommodating motion for first read/write head 34. Similarly, a second read/write actuator controls the motion of second read/write head 36. It is understood that both first read/write actuator 30 and second read/write actuator 32 cooperate with drive electronics 16 to accomplish positioning and reading to writing from optical media 12.

[0025] Also included is a spindle motor 40 for controlling the rotational movement of optical media 12. Drive electronics 16 cooperate with all of these components to appropriately coordinate their functions and provide reading and writing capabilities.

[0026] Referring now to FIG. 2 there is showing a flow chart illustrating the data mapping methodology utilized by disk storage system 10. Reference is also made to Appendix A which includes one embodiment of the pseudo code capable of performing the steps of the present invention. As can be seen, this process starts at Step 200 as necessary. Next in Step 202 the disk layout information is input. As previously mentioned, this disk layout information would depend upon the particular configuration established by the manufacturer and the set-up chosen by the user. For example, the disk layout information will specify how many sides the disk has, how many zones each side includes, and details of the various user defined ranges. Each range is identified as the section of the disk that is allocated for a particular use. In certain circumstances, various areas at the edge may be reserved for set up and testing information. Furthermore, a range in the center may further be reserved for further test information. Lastly, the user areas are defined on the remainder of the disk. These user areas are then available for data storage operations. Additional information may be input by the user at this point to further assist in the address mapping operations. For example, the user will input the number of sectors per track in each of the designated zones, and may designate any pairing information that is desired. This pairing information will specify which zones may preferably be paired together to form an aggregate zone. For example, it is often desired to pair one zone from each side of the disk and collectively use those two zones in data storage operations. Consequently, information can be written to both sides of the disk simultaneously. Additional information about the configurations is shown in Appendix A where one embodiment of the specific stuctures filled in by the user is shown. Again, this information defines the physical structure and striping information for the disk.

[0027] After all disk layout information has been provided, as shown in Step 202, the system will then build a configuration table 206 (CT) in Step 204. The configuration table 206 specifies the details of the various ranges, including the location, and details about the number of sectors included in each range. Further details about the configuration table are described below in relation to FIG. 3.

[0028] Next, in Step 208 the address translation structures are created. These address translation structures include multiple characteristics of the data storage area, all of which is computed from the configuration table. For example, the start and end points and overall length of the various tracks are calculated. Details defining the range of zones can be calculated, the user addressable space can be calculated and defined, etc. Additionally, preexisting translation formulas are identified, which set forth the mechanisms to appropriately perform address translations. The resulting address translation structure is a set of data members which define the disk space. These data members are specifically configured to interact with the translation formulas. As further outlined below, each of these formulas and structures assist in the fast and efficient addressing of data. Again, further details regarding the computation of the Address Translation Structure (ATS) are found in Appendix A which includes one embodiment of the pseudo code capable of carrying out the address mapping functions.

[0029] At this point in the process, the set up operations are completed and the data storage device is ready for either storage or retrieval operations. It will be understood that these are related to the set up operations, however the read steps and storage steps are very independent operations as well.

[0030] In the storage process, the system first receives a storage request from the host computer in Step 220. This request typically includes multiple packets of data, and a logical block address (LBA) identifying these packets. Specifically, Host computer 60 provides the LBA and length of the data. This logical block address is noted by the system and utilized for further mapping operations. Next, in Step 222, the actual address translation takes place utilizing the address translation structure and formulas 210. Specifically, the logical block address is translated to a surface-track-sector address (STSA). Next in Step 226, the data packets provided are stored to the disk at the designated PBAs. Referring again to Appendix A, one example of this address translation is shown in further detail.

[0031] As mentioned above, the disk system of the present invention utilizes two surfaces of storage media 12. In order to speed the data transfer rate, data is written to or read from these two surfaces simultaneously. However, this creates an additional complication in the mapping structures. More specifically, the mapping structure must be able to accommodate a separation of data into a first component and a second component which are stored on the two different sides of the storage media 12. To accommodate this operation, the above-referenced pairing information is used. More specifically, this pairing information provides an association between each zone on a first side of the disk with another zone on a second side of the disk. In one version of the present invention, the zones are paired such that an inner zone on the first surface is paired with an outer zone on the second surface. Each next respective zone on the first surface, moving outward, is then prepared with an associated respective zone on the second surface, moving inward. By pairing the zones in this manner, the data transfer rate can be equalized as the sum of the data being read from the two paired zones will be relatively constant.

[0032] As can be appreciated, this operation, otherwise known as striping (i.e. data is striped to the two sides of the disk), further complicates the data mapping structures. However, the address translation structure and formulas already designated easily accommodate this complication. As mentioned above, the pairing information is initially input during the initialization process. For two paired tracks, the ratio of sectors per track between the two surfaces can be easily computed based on user input information. For example, a first track on a first side of the disk may include 62 sectors per track while a paired zone may include 95 sectors per track. Consequently, the ratio of sectors per track for these two paired zones is 62/95, or 0.65. Using this ratio, the data blocks received can be separated accordingly and directed to the appropriate surface of storage media 12.

[0033] Referring again to FIG. 1, it is seen that controller 20 includes inputs from both first read/write channel 26 and second read/write channel 28. Consequently, controller 20 is capable of separating all data accordingly by cooperating with those components.

[0034] As expected, a similar process is utilized when data is read from the storage media. In Step 240, a data retrieval request is received from the host computer, identifying the logical block address used. This LBA is again utilized to determine the associated STSA. This is accomplished in Step 242, which utilizes the Address Translation Structure 210 and preexisting formulas. Once the STSA is identified, the data located at those physical block addresses can easily be located and retrieved. This retrieval is done in Step 244 with information provided to the host computer.

[0035] As previously mentioned, the configuration table 206 is a basic element of all further mapping operations. Configuration table 206 is illustrated in more detail in FIG. 3. While utilizing configuration table 206 in this way, disk storage system 10 can easily react to changes in the storage media configuration. As previously mentioned, configuration 206 table sets forth the details of various ranges for the disk. For each particular range 260, a start track 262 and an end track 264 are identified. Configuration table 206 also includes the length 266 for this range. In order to determine the specific type of area designated, the zone 268 is designated. Each zone is defined by having a similar set of sectors per track. Thus by identifying the zone, the number of sectors per track is also known. Utilizing this information, the system can easily calculate the number of sectors available in any particular range. Lastly, the type of range 270 is identified. Again, this information provides the system with the necessary information to develop a necessary physical block addressing scheme and to identify those physical block addresses usable for data storage.

[0036] Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. In that the foregoing description of the present invention discloses only exemplary embodiments thereof, it is to be understood that other variations are contemplated as being within the scope of the present invention. Accordingly, the present invention is not limited in the particular embodiments which have been described in detail therein. Rather, reference should be made to the appended claims as indicative of the scope and content of the present invention.