This application claims priority under 35 U.S.C. § 119 from Korean Patent Application 2008-0044718, filed on 14 May 2008 in the names of DaWoon Chung et al., the entirety of which is hereby incorporated by reference for all purposes as if fully set forth herein.
1. Field
This invention pertains to the data storage systems, such as disk drive units, and more particularly to a data storage device having different storage areas and different control information stored in the different areas.
2. Description
There continues to be a demand to process and store an ever-increasing amount and variety of digitized information. This demand is fueled in part by the desire to store and process digitized information from sources which generate a large volume of data, such as audio and video programming material. The demand for storing such large amounts of data in turn drives a desire for devices, including disk drive units, which can more efficiently store large amounts of data.
In disk drive unit 100, repeatable runout is caused by the center of rotation being offset from the physical center of the disk (i.e., misalignment between the center of disk 200 and spindle motor 14 on which disk 200 is mounted), as well as disk wobble, etc. Repeatable runout causes a misalignment between read/write head 16 of the disk drive unit 100 and a track 210 that it is following on disk 200. Repeatable runout is the same for every revolution of disk 200. Accordingly, RRO Correction Code (RCC) portion 450 is written in servo sector 320 of disk 200 to correct the offset between read/write head 16 of disk drive unit 100 and track 210. RCC portions 450 are positioned after every servo sector 320 for correcting the head position when read/write head 16 performs a track seeking or track following operation.
In general there are areas or zones of disk 200 where the repeatable runout error is negligible, or at least small enough (e.g., less than some predetermined value) that correction is not required for the read/write head to properly follow the track 210. However, the RCC portion 450 is still recorded for these areas or zones, even though it is not needed.
So some of the RCC portions 450 are unused portions, and therefore wasted areas, of disk 200.
Accordingly, it would be desirable to provide a new data storage device, such as a disk drive unit, that corrects a repeatable runout error with a more efficient utilization of disk space. It would also be desirable to provide a new method of producing such a data storage device. It would further be desirable to provide a new method of correcting repeatable runout error in a data storage device.
In one aspect of the inventive concept, a disk drive unit comprises at least one disk for storing data therein, the disk being divided into a plurality of tracks, the disk having at least a first set of tracks that each have stored therein at least one repeatable runout correction code for at least one area of the track, and the disk having at least a second set of tracks that each do not have stored therein any repeatable runout correction codes.
In another aspect of the inventive concept, a method is provided for operating a disk drive unit having at least one disk for storing data therein, the disk being divided into a plurality of tracks. The method comprises: receiving at the disk drive unit a read/write command for the disk; determining a target area of the disk to which the read/write command pertains; determining whether a track in the target area of the disk has stored therein a repeatable runout correction code for at least one area of the track; adjust a servo control signal for accessing the track in the target area of the disk in response to whether the track has stored therein a repeatable runout correction code; and performing a read/write operation for the track in the target area of the disk using the adjusted servo control signal.
In yet another aspect of the inventive concept, a method is provided for arranging a data storage device. The method comprises providing at least one disk divided into a plurality of tracks, the disk having at least a first set of tracks that each have stored therein at least one repeatable runout correction code for at least one area of the track, and the disk having at least a second set of tracks that each do not have stored therein any repeatable runout correction codes.
In still another aspect of the inventive concept, a data storage device is divided into a plurality data storage areas, wherein a first set of data storage areas each includes a control information area storing therein information pertaining to the data storage area associated therewith, and wherein a second set of data storage areas each do not include the control information area.
In a further aspect of the inventive concept, a data storage device is divided into a plurality data storage areas, each data storage area having associated therewith a control information storage area pertaining to data stored therein, wherein a first set of control information areas each include a first field storing therein a first set of information pertaining to the data storage areas associated therewith, and wherein a second set of control information areas each include a second field storing therein a second set of information pertaining to the data storage areas associated therewith, wherein the first field is different than the second field.
In yet a further aspect of the inventive concept, a method is provided for operating a data storage device. The method comprises: receiving at the data storage device a read/write command for the data storage device; determining a target area of the data storage device to which the read/write command pertains; determining whether the target area of the data storage device has stored therein control information pertaining to the data storage areas associated therewith; and adjusting a read/write operation at the target area in response to whether the target area of the data storage device has stored therein the control information pertaining to the data storage area associated therewith.
In still a further aspect of the inventive concept, a method provides a data storage device divided into a plurality of data storage areas. The method comprises providing at least a first set of data storage areas each having stored therein a set of control information pertaining to the data storage area associated therewith, and further providing at least a second set of data storage areas each not having stored therein the set of control information.
In one embodiment, each disk 510 of data storage device 500 has a plurality of tracks, including at least a first set of tracks that each have stored therein at least one Repeatable Runout (RRO) Correction Code (RCC) for at least one area of the track, and having at least a second set of tracks that each do not have stored therein any RCCs.
In a step S801 a zone counter for disk 510 is initialized to 0. The zone counter may be included in controller 42. Disk 510 may be divided into areas or zones which, for example, may correspond to tracks, or a certain number of tracks (e.g., groups of 1000 tracks each) of disk 510. The zone counter counts through each zone or area of disk 510 as the method 800 is executed, as explained below.
In a step S802 the RCC information stored in the current zone i, is counted or added together to produce a value N(i). For example, in zone 0 (i=0), then the RCC information in zone 0 is counted to produce N(0).
In a step S803 N(i) is compared against a threshold value (TH). The threshold value TH is a value for which servo control for reading and writing to disk 510 is possible without using any RCC information. If N(i) is less than TH, then the process proceeds to step S804. Otherwise, the process proceeds to step S805.
In one embodiment, the TH value is predetermined by a test or a statistical measurement. In one illustrative example, each zone or area of disk 510 may include 1000 tracks and the threshold value TH may be set to 1% of the tracks in each zone (i.e., 10 tracks). In that case, in one embodiment if ten (10) or more of the tracks in zone i have the RCC values, then it is determined that RCC information should be stored in the tracks of zone i to maintain servo control for reading and writing to the tracks, and the process proceeds to step S805. Otherwise, if less than ten (10) tracks in zone i have the RCC values, then the process proceeds to step S804.
In step S804 the current counter value i—corresponding to a zone or area of disk 510 where it was determined in step S803 that N(i) value is less than the threshold value TH—is placed into a list LIST_RCC(OFF). The list LIST_RCC(OFF) identifies those zones or areas where the tracks will not have RCC values stored. The list LIST_RCC(OFF) may be stored in a register in controller 42, or in RAM 52, or in another convenient location in data storage device 500.
In step S805 the current counter value i is compared a maximum value i_max. Here, i_max corresponds to the last zone or area of the divided disk (i.e., the first zone of the divided disk 510 is i=0 and the last zone or area is i=i_max). If the counter value i is not equal to the maximum value i_max, then the process proceeds to step S806, where the counter value i is incremented by +1, and then the process returns to step S802. Otherwise, if the counter value i is equal to the maximum value i_max, then the process proceeds to step S807.
In step S807 the RCC portions of the servo sectors of the tracks in the zones or areas which are identified in the list LIST_RCC(OFF) are changed to other usage (e.g., changed to data storage areas). Also, in one embodiment, information identifying those tracks that do not have RCC values stored thereon is saved in an RCC table in data storage device 500. In one embodiment, the RCC table may comprise flags for all of the zones or areas of disk 510, and the flags are set to indicate that which of those zones or areas will not (or, in an alternative arrangement, will) include RCC values. In another embodiment, the RCC table may be a list of the zone numbers or area numbers of those zones or areas will not (or in an alternative arrangement, will) include RCC values. Other arrangements are possible. In some embodiments, the RCC table may be stored in a Maintenance Cylinder (MC) region of disk 510 or in non-volatile memory (e.g., ROM 50). As explained in greater detail below, during a data read/write operation, information from the RCC table is employed to determine whether a target track includes the RCC or not.
In an alternative embodiment, instead of creating RCC portions for all tracks, and then “converting” the RCC portions of those tracks that do not require the RCC for proper servo control to other uses, the process only creates the RCC portions for those tracks that do require the RCC for proper servo control after the determination is made in steps S801-S806 as to which tracks require the RCC. Again, other arrangements are possible.
In step S902 it is determined whether a track in a target area or zone of disk 510 for the read/write command has stored therein a repeatable runout correction code (RCC) for at least one area of the track. As noted above with respect to
In a step S903 when a track seeking/following operation is performed for the read/write operation, then a servo control signal is adjusted based on the RCC information retrieved from the RCC table. The servo control signal is a control signal for generating a servo sector gate open/close signal and a data sector gate open/close signal, as will be explained in greater detail below with respect to
Then, in a step S904, a read/write operation is performed based on the servo control signal which is produced using the RCC information retrieved from the RCC table, and which in turn adjusts the timing of pulses for opening and closing the servo sector gate and the data sector gate, as will be explained in greater detail below with respect to
By employing methods such as those described above with respect to
Beneficially, Ts′<Ts and Td′>Td. In this case, the length of each data sector 72 is increased compared to the data sector 62 because the area of track 610 used for the RCC is changed to data storage area.
The RCC portion is a physical area of disk 510 but that portion indicates as a logical portion for the system control data area in the logical data structure of disk 510, and that portion is using optionally in accordance with the RCC table which stores information which identifies where the RCC is used or not used in each area of disk 510.
Principles described above with respect to a disk drive unit can be generalized to other data storage devices.
For example, in one embodiment, a data storage device is divided into a plurality data storage areas, wherein a first set of data storage areas each includes a control information area storing therein information pertaining to the data storage area associated therewith, and wherein a second set of data storage areas each do not include the control information area. A method of operating such a data storage device includes receiving at the data storage device a read/write command for the data storage device; determining a target area of the data storage device to which the read/write command pertains; determining whether the target area of the data storage device has stored therein control information pertaining to the data storage areas associated therewith; and adjusting a read/write operation at the target area in response to whether the target area of the data storage device has stored therein the control information pertaining to the data storage area associated therewith.
In another example embodiment, a data storage device is divided into a plurality data storage areas, each data storage area having associated therewith a control information storage area pertaining to data stored therein, wherein a first set of control information areas each include a first field storing therein a first set of information pertaining to the data storage areas associated therewith, and wherein a second set of control information areas each include a second field storing therein a second set of information pertaining to the data storage areas associated therewith, wherein the first field is different than the second field.
While preferred embodiments are disclosed herein, many variations are possible which remain within the concept and scope of the invention. Such variations would become clear to one of ordinary skill in the art after inspection of the specification, drawings and claims herein. The invention therefore is not to be restricted except within the spirit and scope of the appended claims.
Number | Date | Country | Kind |
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10-2008-0044718 | May 2008 | KR | national |