# Patent

## Title
Data management for a data storage device using a last resort zone

## Abstract

A data storage device (DSD) includes a non-volatile memory (NVM) media for storing data. A last resort zone of the NVM media is associated with a higher risk of data loss or data corruption than other portions of the NVM media and is reserved as unavailable for storing data. It is determined whether a current data storage capacity and/or an environmental condition for the NVM media has reached a threshold. The last resort zone is set as available for storing data if it is determined that the threshold has been reached and data is written in the last resort zone.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No. 61/968,966 , filed on Mar. 21, 2014, which is hereby incorporated by reference in its entirety.


BACKGROUND
Data Storage Devices (DSDs) are often used to record data onto or to reproduce data from a storage media. One type of storage media includes a rotating magnetic disk where a magnetic head of the DSD can read and write data in tracks on a surface of the disk.
Data stored on the disk may become susceptible to corruption or data loss due to a variety of conditions. For example, data stored on a particular area of the disk surface may become unreadable if the DSD is dropped and components of the DSD contact the disk surface. In another example, contaminants or surface defects may also cause loss or corruption of data written on the disk.



BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the embodiments of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the disclosure and not to limit the scope of what is claimed.
FIG. 1 is a block diagram depicting a Data Storage Device (DSD) according to an embodiment.
FIG. 2A is an example of a translation table with a last resort zone that has been reserved as unavailable for storing data according to an embodiment.
FIG. 2B depicts the translation table of FIG. 2B after the last resort zone has been set as available for storing data according to an embodiment.
FIG. 3 is a flowchart for a data management process according to an embodiment.
FIG. 4 is a flowchart for a data management process according to another embodiment.



DETAILED DESCRIPTION
In the following detailed description, numerous specific details are set forth to provide a full understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the various embodiments disclosed may be practiced without some of these specific details. In other instances, well-known structures and techniques have not been shown in detail to avoid unnecessarily obscuring the various embodiments.
FIG. 1 shows computer system 100 according to an embodiment which includes host 101 and Data Storage Device (DSD) 106. Computer system 100 can be, for example, a computer system (e.g., server, desktop, mobile/laptop, tablet, smartphone, etc.) or other electronic device such as a digital video recorder (DVR). In this regard, computer system 100 may be a stand-alone system or part of a network. Those of ordinary skill in the art will appreciate that system 100 and DSD 106 can include more or less than those elements shown in FIG. 1 and that the disclosed processes can be implemented in other environments.
In the example embodiment of FIG. 1, DSD 106 includes both solid state memory 128 and disk 150 for storing data. In this regard, DSD 106 can be considered a Solid State Hybrid Drive (SSHD) in that it includes both solid state Non-Volatile Memory (NVM) media and disk NVM media. In other embodiments, each of disk 150 or solid state memory 128 may be replaced by multiple Hard Disk Drives (HDDs) or multiple Solid State Drives (SSDs), respectively, so that DSD 106 includes pools of HDDs or SSDs. In yet other embodiments, the NVM media of DSD 106 may only include disk 150 or solid state memory 128.
DSD 106 includes controller 120 which includes circuitry such as one or more processors for executing instructions and can include a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), hard-wired logic, analog circuitry and/or a combination thereof. In one implementation, controller 120 can include a System on a Chip (SoC).
Host interface 126 is configured to interface DSD 106 with host 101 and may interface according to a standard such as, for example, PCI express (PCIe), Serial Advanced Technology Attachment (SATA), or Serial Attached SCSI (SAS). As will be appreciated by those of ordinary skill in the art, host interface 126 can be included as part of controller 120.
Sensor 142 detects an environmental condition of DSD 106, such as a temperature, acceleration, or vibration of DSD 106, and provides an input to controller 120 based on the detected condition. In some embodiments, controller 120 may modify operation of DSD 106 based on the input received from sensor 142. As discussed in more detail below, controller 120 may also set a last resort zone of NVM media as available for storing data if it is determined that an environmental condition has reached a threshold.
In the example of FIG. 1, disk 150 is rotated by a spindle motor (not shown). DSD 106 also includes head 136 connected to the distal end of actuator 130 which is rotated by Voice Coil Motor (VCM) 132 to position head 136 in relation to disk 150. Controller 120 can control the position of head 136 and the rotation of disk 150 using VCM control signal 30 and SM control signal 34, respectively.
As appreciated by those of ordinary skill in the art, disk 150 may form part of a disk pack with additional disks radially aligned below disk 150. In addition, head 136 may form part of a head stack assembly including additional heads with each head arranged to read data from and write data to a corresponding surface of a disk in a disk pack.
Disk 150 includes a number of radial spaced, concentric tracks (not shown) for storing data on a surface of disk 150. The tracks on disk 150 are grouped together into zones of tracks (e.g., zones 152 and last resort zone 154) with each track divided into a number of sectors that are spaced circumferentially along the tracks.
In some implementations, the tracks on disk 150 are written by a write element of head 136 using Shingled Magnetic Recording (SMR) so as to overlap adjacent tracks. SMR provides a way of increasing the amount of data that can be stored in a given area on disk 150 by overlapping tracks like roof shingles. The non-overlapping portion then serves as a narrow track that can be read by a read element of head 136.
Although a higher number of tracks per inch is ordinarily possible with SMR, the overlap in tracks can generally prevent new writes to a previously overlapped track since such new writes would affect data written in the overlapping track. For this reason, tracks are usually sequentially written in SMR implementations to avoid affecting previously written data.
In the embodiment of FIG. 1, last resort zone 154 is associated with a higher risk of data loss than other portions of the NVM media of DSD 106. For example, last resort zone 154 can include an area of disk 150 that may often become damaged as a result of mechanical shock to DSD 106. Such mechanical shock may occur when DSD 106 is dropped during operation or when DSD 106 is initially tested by a manufacturer.
In FIG. 1, last resort zone 154 is located in an Outer Diameter (OD) portion of disk 150. The OD portion of disk 150 may become damaged when DSD 106 is dropped during operation as DSD 106 takes precautionary measures to move head 136 away from disk 150 to reduce the likelihood of damage to disk 150 upon impact. In addition, the OD portion of disk 150 may become damaged during a manufacturer's mechanical shock testing of DSD 106 if disk 150 is addressed beginning at the OD portion of disk 150.
In other embodiments, last resort zone 154 can be located in different portions of disk 150 or in a portion of solid state memory 128. In one embodiment, last resort zone 154 is located in an Inside Diameter (ID) portion of disk 150. The ID portion of disk 150 may be associated with a higher risk of data loss due to an increased amount of contaminants near the ID portion or from other disk surface irregularities caused by clamping disk 150 to a spindle (not shown). In other embodiments, last resort zone 154 can be assigned during operation or factory testing as a zone with more than a predetermined number of defects or errors.
In addition to disk 150, the NVM media of DSD 106 also includes solid state memory 128 for storing data. While the description herein refers to solid state memory generally, it is understood that solid state memory may comprise one or more of various types of memory devices such as flash integrated circuits, Chalcogenide RAM (C-RAM), Phase Change Memory (PC-RAM or PRAM), Programmable Metallization Cell RAM (PMC-RAM or PMCm), Ovonic Unified Memory (OUM), Resistance RAM (RRAM), NAND memory (e.g., Single-Level Cell (SLC) memory, Multi-Level Cell (MLC) memory, or any combination thereof), NOR memory, EEPROM, Ferroelectric Memory (FeRAM), Magnetoresistive RAM (MRAM), other discrete NVM chips, or any combination thereof. Where DSD 106 stores data in solid state memory 128, last resort zone 154 could be a location such as a page, block, die, etc. in solid state memory 128 that may have certain detected or known weaknesses/conditions similar to those described above, and the embodiments described herein can equally apply to such cases as well.
Volatile memory 140 can include, for example, a Dynamic Random Access Memory (DRAM) which can be used by DSD 106 to temporarily store data. Data stored in volatile memory 140 can include data read from NVM media (e.g., disk 150 or solid state memory 128), data to be written to NVM media, instructions loaded from firmware of DSD 106 for execution by controller 120, or data used in executing firmware of DSD 106.
As shown in the embodiment of FIG. 1, volatile memory 140 stores translation table 22, which provides a mapping between Logical Block Addresses (LBAs) used by host 101 to address data and physical locations (e.g., Physical Block Addresses (PBAs)) indicating physical locations on disk 150 or in solid state memory 128. In one implementation, a back-up copy of a translation table is stored on disk 150 which is updated to account for changes to translation table 22 stored in volatile memory 140. In other embodiments, translation table 22 may be stored in a different location such as in solid state memory 128. Translation table 22 is described in more detail below with reference to FIGS. 2A and 2B.
In operation, host interface 126 receives read and write commands from host 101 via host interface 126 for reading data from and writing data to the NVM media of DSD 106. In response to a write command from host 101, controller 120 may buffer the data to be written for the write command in volatile memory 140.
For data to be written to disk 150, controller 120 can encode the buffered data into write signal 32 which is provided to head 136 for magnetically writing data to the surface of disk 150.
In response to a read command for data stored on disk 150, controller 120 positions head 136 via VCM control signal 30 to magnetically read the data stored on the surface of disk 150. Head 136 sends the read data as read signal 32 to controller 120 for decoding, and the data is buffered in volatile memory 140 for transferring to host 101.
For data to be stored in solid state memory 128, controller 120 receives data from host interface 126 and may buffer the data in volatile memory 140. In one implementation, the data is then encoded into charge values for charging cells (not shown) of solid state memory 128 to store the data.
In response to a read command for data stored in solid state memory 128, controller 120 in one implementation reads current values for cells in solid state memory 128 and decodes the current values into data that can be transferred to host 101. Such data may be buffered by controller 120 before transferring the data to host 101 via host interface 126.
FIG. 2A provides an example of translation table 22 with last resort zone 154 reserved as unavailable for storing data according to an embodiment. In the embodiment of FIGS. 2A and 2B, controller 120 manages access to NVM media using translation table 22. In this regard, translation table 22 is used to map LBAs for associated data to PBAs corresponding to physical locations where the associated data is stored in the NVM media. Controller 120 maintains translation table 22 in volatile memory 140 to keep track of the changes made to the data stored in the NVM media of DSD 106. As noted above, translation table 22 may also be stored, or alternatively stored, in solid state memory 128 or disk 150.
In some implementations, translation table 22 is used as part of an indirection process for SMR zones on disk 150. When data is updated for a particular LBA, the update is often written in a different location on disk 150 than where the data for the LBA was previously written to avoid having to rewrite an entire SMR zone of overlapping tracks. A translation table, such as translation table 22, can be used to keep track of where the current versions of the data are stored for a particular LBA.
As shown in FIG. 2A, each entry (i.e., row) of translation table 22 includes an LBA and a PBA which is mapped to the LBA for the entry. In other embodiments, translation table 22 can include LBA ranges mapped to PBA ranges which can be represented with a starting address and an extent length.
The PBAs in translation table 22 indicate locations in the NVM media of DSD 106 such as locations on disk 150 or in solid state memory 128. Entries 24 of translation table 22 include PBAs for last resort zone 154 and entries 26 of translation table 22 include PBAs for portions of the NVM media that are outside of last resort zone 154. In the example of FIG. 2A, the PBAs for last resort zone 154 begin at PBA 0 and continue to PBA n. The PBAs for the portions of NVM media outside of last resort zone 154 begin at PBA n+1 and continue to PBA n+m.
As noted above, the physical location of last resort zone 154 is not limited to an OD portion of disk 150 in other embodiments. Similarly, the range of PBAs identifying last resort zone 154 is not limited to a particular range of PBAs. For example, the range of PBAs for last resort zone 154 in other embodiments may occur at the end of a total PBA range for the NVM media or between the end and beginning of the total PBA range for the NVM media.
In the example of FIG. 2A, last resort zone 154 has been reserved by having no LBAs allocated to entries 24 and with LBAs having been allocated to locations outside of last resort zone 154. This is shown by the LBAs allocated for entries 26 but not for entries 24. When performing read and write commands for host 101, DSD 106 will access the portions of the NVM media corresponding to entries 26 without accessing last resort zone 154. Since last resort zone 154 is not allocated LBAs, it is not yet visible or available to host 101.
Although entries 26 have been allocated LBAs 0 to m, the LBAs for entries 26 do not need to be sequentially ordered with respect to their respective PBAs. Moreover, the use of LBA indirection for disk 150 or solid state memory 128 can result in a non-sequential ordering of LBAs with respect to the corresponding PBAs.
Once a storage capacity associated with entries 26 has reached a threshold, controller 120 can set last resort zone 154 as available for storing data by allocating LBAs to entries 24 for last resort zone 154. This can ordinarily allow for DSD 106 to reduce the likelihood of data loss or corruption by waiting until all or most of the NVM media outside of last resort zone 154 has been used before storing data in the more vulnerable last resort zone 154.
In other embodiments, controller 120 can set last resort zone 154 as available for storing data based on whether an environmental condition for the NVM media has reached a threshold. For example, sensor 142 may detect a high operating temperature for solid state memory 128 or disk 150 that may make it more likely to encounter an error in storing or retrieving data from the NVM media. Sensor 142 can provide an input to controller 120 indicating a high temperature condition, and controller 120 may then set last resort zone 154 as available for storing data by allocating LBAs to entries 24 for last resort zone 154. This can ordinarily allow for DSD 106 to save less vulnerable portions of the NVM media for storing data when there is less likely to be an error due to the environmental condition. Controller 120 may also follow particular write settings to safeguard against data loss when storing data in last resort zone 154 or may store a duplicate copy of the data to protect against data loss or corruption due to the environmental condition.
In another example, sensor 142 may detect an environmental condition of a high vibration condition that may make it more likely to encounter an error in storing or retrieving data from the NVM media. Sensor 142 can provide an input to controller 120 indicating the high vibration condition, and controller 120 may then set last resort zone 154 as available for storing data by allocating LBAs to entries 24 for last resort zone 154. Different write settings can then be used when writing data in last resort zone 154 to reduce the likelihood of an error during the environmental condition.
In yet other embodiments, controller 120 can set last resort zone 154 as available for storing data when both a current data storage capacity and an environmental condition have reached a threshold. In other words, controller 120 may only set last resort zone 154 as available after a certain amount of data has been stored outside of last resort zone 154 and sensor 142 detects a particular environmental condition.
As noted above, DSD 106 may also change the way in which it writes data in last resort zone 154 when compared to areas outside of last resort zone 154. For example, controller 120 may perform a write verification process (e.g., a conditioned write verify process) for data written in last resort zone 154 where data is read after it has been written to verify the written data.
In another example, controller 120 may reduce the number of write retries when attempting to write data in a sector of last resort zone 154. In more detail, controller 120 may control head 136 to attempt to write data in a particular sector for a predetermined number of write retries before relocating the data to a different sector such as a spare sector. Controller 120 may reduce the number of write retries such as from ten write retries to only three when writing data in last resort zone 154. This can be done to improve the time for completing write commands in last resort zone 154 since it may be more likely that additional write retries will be unsuccessful if last resort zone 154 has been identified as having a large amount of defects.
In addition, controller 120 may adjust write settings for writing data in last resort zone 154 by changing a track density for writing data in last resort zone 154. In one example, the track density or a number of Tracks Per Inch (TPI) can be decreased so as to reduce the chances of encountering errors when reading or writing data in last resort zone 154. Since more errors can be expected when tracks are in closer proximity to each other, lowering the track density for last resort zone 154 can generally lessen the likelihood of errors in last resort zone 154, which is already more susceptible to errors.
Controller 120 may also limit the types of data written in last resort zone 154. In this regard, the data written in last resort zone 154 may be required to have a duplicate copy stored outside of last resort zone 154 to prevent loss of the data. In one example, last resort zone 154 may be used as a scratch area for performing garbage collection of zones 152 so that a copy of data stored in a particular zone 152 is stored in last resort zone 154 while the zone 152 is garbage collected.
Less stringent write settings may be used based on whether there is a duplicate copy of the data stored outside of last resort zone 154. For example, as long as a copy of the data exists elsewhere in the NVM media, controller 120 may relax the write settings for writing the data in last resort zone 154 by, for example, not performing a write verification of the copy stored in last resort zone 154.
In another implementation, the data written in last resort zone 154 may be data that is accessed with a reading frequency and/or a writing frequency outside of a threshold frequency or data with a lower priority, since this data may be at a higher risk of loss or corruption by being stored in last resort zone 154. In one such example, controller 120 may store cold data in last resort zone 154 that is not frequently accessed for reading or writing.
FIG. 2B depicts translation table 22 after last resort zone 154 has been set as available for storing data according to an embodiment. As shown in FIG. 2B, LBAs have been allocated to entries 24 for last resort zone 154. The allocated LBAs begin with m+1 and continue to m+n. As discussed in more detail below with reference to FIG. 3, the allocation of LBAs to last resort zone 154 occurs after controller 120 determines that a current data storage capacity for the NVM media has reached a threshold. After allocating the LBAs to last resort zone 154, DSD 106 can perform read and write commands in last resort zone 154 and last resort zone 154 becomes visible or available to host 101.
FIG. 3 is a flowchart for a data management process that can be performed by controller 120 according to an embodiment. The process of FIG. 3 begins in block 304 with controller 120 reserving last resort zone 154 as unavailable for storing data. This can be accomplished as noted above with FIG. 2A by allocating LBAs to portions of the NVM media outside of last resort zone 154 without allocating LBAs to last resort zone 154.
In block 308, controller 120 determines whether a current data storage capacity and/or an environmental condition has reached a threshold. The threshold for the current data storage capacity can be, for example, a total capacity for the portions of NVM media outside of last resort zone 154 or within a certain percentage of such a total capacity. In some implementations, this can include determining a remaining amount of data capacity available for the portion of the NVM media corresponding to entries 26 or to entries 24 and 26 in translation table 22. In other implementations, the current data storage capacity can include an amount of data stored in the NVM media for the portion of the NVM media corresponding to entries 26 or to entries 24 and 26.
The threshold for an environmental condition can be, for example, a particular temperature or an amount of vibration detected by sensor 142. In other examples, reaching the threshold may require both a certain data storage capacity and a particular environmental condition such as only 95% of the NVM media being available to store data and a temperature of DSD 106 being above a certain operating temperature.
If it is determined in block 308 that the threshold has not been reached, the process will return to block 308 to again determine whether the threshold has been reached. The determination of block 308 may be performed at a fixed interval of time, after certain events of DSD 106, or during idle periods of DSD 106. In some implementations, controller 120 may keep a running total of the current data storage capacity such that the current data storage capacity is updated each time data is stored in the NVM media.
If it is determined that the threshold has been reached in block 308, controller 120 in block 310 sets last resort zone 154 as available for storing data. As discussed above, this can be accomplished by allocating LBAs to last resort zone 154. In block 314, data is written in last resort zone 154 until last resort zone 154 is made available for reuse in block 316. In more detail, last resort zone 154 may be garbage collected or otherwise freed up as part of a maintenance operation of DSD 106. Once last resort zone 154 has been made available for reuse, the process of FIG. 3 returns to block 304 to repeat the process for last resort zone 154.
FIG. 4 is a flowchart for a different data management process that can be performed by controller 120 according to an embodiment. The process of FIG. 4 begins in block 402 with controller 120 optionally assigning last resort zone 154 to a portion of the NVM media of DSD 106. The assignment of last resort zone 154 may occur during an initial startup of DSD 106, a factory testing process of DSD 106, or in the field during operation of DSD 106. In this regard, controller 120 may reassign last resort zone 154 from a default zone to a new zone during operation of DSD 106. In other embodiments, last resort zone 154 may be set by the manufacturer and remain at a fixed location.
In block 404, controller 120 reserves last resort zone 154 as unavailable for storing data. This can be accomplished as noted above with FIG. 2A by allocating LBAs to portions of the NVM media outside of last resort zone 154 without allocating LBAs to last resort zone 154.
In block 406, controller 120 determines a current data storage capacity for the NVM media. In some implementations, this can include determining a remaining amount of data capacity available for the portion of the NVM media corresponding to entries 26 or to entries 24 and 26 in translation table 22. In other implementations, the current data storage capacity can include an amount of data stored in the NVM media for the portion of the NVM media corresponding to entries 26 or to entries 24 and 26.
In block 408, controller 120 determines whether a current data storage capacity and/or an environmental condition has reached a threshold as discussed above with reference to block 308 of FIG. 3.
If it is determined in block 408 that the threshold has not been reached, the process returns to block 406 to determine a new current data storage capacity. The determination of the current data storage capacity in block 406 may be performed at a fixed interval of time, after certain events of DSD 106, or during idle periods of DSD 106. In some implementations, controller 120 may keep a running total of the current data storage capacity such that the current data storage capacity is updated each time data is stored in the NVM media.
If it is determined that the threshold has been reached in block 408, controller 120 in block 410 sets last resort zone 154 as available for storing data. As discussed above, this can be accomplished by allocating LBAs to last resort zone 154.
In block 412, controller 120 optionally adjusts write settings for last resort zone 154. As noted above, this can, for example, include reading data written in last resort zone 154 to verify that the data has been correctly written, changing a track density for last resort zone 154, or adjusting the number of write retires when writing data in last resort zone 154. The type of data allowed to be stored in last resort zone 154 may also be set in block 412, such as restricting the data stored in last resort zone 154 to copies of data stored elsewhere or restricting the data stored in last resort zone 154 to data of a lower priority or lower frequency of access. In other embodiments, data may be written in last resort zone 154 without any adjustment in write settings or type of data allowed to be stored in last resort zone 154.
In block 414, controller 120 controls head 136 to write data in last resort zone 154. After last resort zone 154 is made available for reuse as discussed above for block 316 of FIG. 3, the process of FIG. 4 returns to block 402 to optionally assign last resort zone 154.
Those of ordinary skill in the art will appreciate that the various illustrative logical blocks, modules, and processes described in connection with the examples disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Furthermore, the foregoing processes can be embodied on a computer readable medium which causes a processor or computer to perform or execute certain functions.
To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, and modules have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Those of ordinary skill in the art may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
The various illustrative logical blocks, units, modules, and controllers described in connection with the examples disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The activities of a method or process described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The steps of the method or algorithm may also be performed in an alternate order from those provided in the examples. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable media, an optical media, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an Application Specific Integrated Circuit (ASIC).
The foregoing description of the disclosed example embodiments is provided to enable any person of ordinary skill in the art to make or use the embodiments in the present disclosure. Various modifications to these examples will be readily apparent to those of ordinary skill in the art, and the principles disclosed herein may be applied to other examples without departing from the spirit or scope of the present disclosure. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the disclosure is, therefore, indicated by the following claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

## Claims

1. A data storage device (DSD) comprising:
non-volatile memory (NVM) media including a last resort zone associated with a higher risk of data loss or data corruption than other portions of the NVM media; and
a controller configured to:
assign the last resort zone to a portion of the NVM media when more than a predetermined number of defects or errors are identified in the portion of the NVM;
reserve the last resort zone as unavailable for storing data;
determine whether a current data storage capacity and/or an environmental condition for the NVM media has reached a threshold;
set the last resort zone as available for storing data if it is determined that the threshold has been reached; and
write data in the last resort zone.

2. The DSD of claim 1, wherein the NVM media includes a magnetic media.

3. The DSD of claim 1, wherein the NVM media includes a solid state memory.

4. The DSD of claim 1, wherein the controller is further configured to manage access of the NVM media using an address translation table.

5. The DSD of claim 1, wherein the controller is further configured to set the last resort zone as available for storing data by allocating logical addresses to the last resort zone.

6. The DSD of claim 1, wherein the controller is further configured to reserve the last resort zone by allocating logical addresses to portions of the NVM media outside of the last resort zone without allocating logical addresses to the last resort zone.

7. The DSD of claim 1, wherein the NVM media includes a disk and the last resort zone is located on the disk.

8. The DSD of claim 7, wherein the last resort zone is located in an outer diameter portion of the disk.

9. The DSD of claim 8, further comprising a head for reading and writing data on the disk, and wherein the last resort zone is more susceptible to contact by the head than other portions of the disk.

10. The DSD of claim 7, wherein the last resort zone is located in an inner diameter portion of the disk.

11. The DSD of claim 7, wherein the controller is further configured to adjust write settings for writing data in the last resort zone.

12. The DSD of claim 11, wherein each track on the disk includes a plurality of sectors, and wherein the controller is further configured to:
attempt to write data in a particular sector of the plurality of sectors for a predetermined number of write retries; and
adjust write settings for writing data in the last resort zone by reducing the predetermined number of write retries when attempting to write data in the last resort zone.

13. The DSD of claim 11, wherein the controller is further configured to adjust write settings for writing data in the last resort zone by reading data written in the last resort zone to verify the data written in the last resort zone.

14. The DSD of claim 11, wherein the controller is further configured to adjust write settings for writing data in the last resort zone by changing a track density for writing data in the last resort zone.

15. The DSD of claim 11, wherein the controller is further configured to adjust write settings for writing data in the last resort zone based on whether there is a duplicate copy of the data written in the NVM media outside of the last resort zone.

16. The DSD of claim 1, wherein the data written in the last resort zone includes data accessed with a reading frequency and/or a writing frequency outside of a threshold frequency.

17. The DSD of claim 1, wherein the environmental condition includes at least one of an operating temperature and a vibration condition of the DSD.

18. A method for operating a data storage device (DSD) including non-volatile memory (NVM) media, the method comprising:
assigning a last resort zone to a portion of the NVM media when more than a predetermined number of defects or errors are identified in the portion of the NVM, wherein the last resort zone is associated with a higher risk of data loss or data corruption than other portions of the NVM media;
reserving the last resort zone of the NVM media as unavailable for storing data;
determining whether a current data storage capacity and/or an environmental condition for the NVM media has reached a threshold;
setting the last resort zone as available for storing data if it is determined that the threshold has been reached; and
writing data in the last resort zone.

19. The method of claim 18, wherein the NVM media includes a magnetic media.

20. The method of claim 18, wherein the NVM media includes a solid state memory.

21. The method of claim 18, further comprising managing access of the NVM media using an address translation table.

22. The method of claim 18, further comprising setting the last resort zone as available for storing data by allocating logical addresses to the last resort zone.

23. The method of claim 18, further comprising reserving the last resort zone by allocating logical addresses to portions of the NVM media outside of the last resort zone without allocating logical addresses to the last resort zone.

24. The method of claim 18, wherein the NVM media includes a disk and the last resort zone is located on the disk.

25. The method of claim 24, wherein the last resort zone is located in an outer diameter portion of the disk.

26. The method of claim 25, wherein the last resort zone is more susceptible to contact by a head of the DSD than other portions of the disk.

27. The method of claim 24, wherein the last resort zone is located in an inner diameter portion of the disk.

28. The method of claim 24, further comprising adjusting write settings for writing data in the last resort zone.

29. The method of claim 28, wherein the disk includes a plurality of sectors for storing data, and wherein the method further comprises:
attempting to write data in a particular sector of the plurality of sectors for a predetermined number of write retries; and
adjusting write settings for writing data in the last resort zone by reducing the predetermined number of write retries when attempting to write data in the last resort zone.

30. The method of claim 28, further comprising adjusting write settings for writing data in the last resort zone by reading data written in the last resort zone to verify the data written in the last resort zone.

31. The method of claim 28, further comprising adjusting write settings for writing data in the last resort zone by changing a track density for writing data in the last resort zone.

32. The method of claim 28, further comprising adjusting write settings for writing data in the last resort zone based on whether there is a duplicate copy of the data written in the NVM media outside of the last resort zone.

33. The method of claim 18, wherein the data written in the last resort zone includes data accessed with a reading frequency and/or a writing frequency outside of a threshold frequency.

34. The method of claim 18, wherein the environmental condition includes at least one of an operating temperature and a vibration condition of the DSD.