Patent Publication Number: US-2022229593-A1

Title: Detection Of Scattered Data Locations

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional patent application Ser. No. 63/139,618, filed Jan. 20, 2021, which is herein incorporated by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     Embodiments of the present disclosure generally relate to data storage devices, such as solid state drives (SSDs), specifically utilizing the data storage device memory in the execution of host commands. 
     Description of the Related Art 
     While working with Non-Volatile Memory Express (NVMe) protocol over peripheral component interconnect express (PCIe), the protocol allows a storage system to use memory located in a controller of a data storage device as if the memory were part of a host device memory, such as the host device dynamic random access memory (DRAM). The controller memory is further divided into two regions, a controller memory buffer (CMB) and a persistence memory region (PMR). 
     The NVMe standard 1.3d defines that for a specific command, the physical region page/scatter gather list (PRP/SGL) may be located either entirely in the CMB or entirely out of the CMB. Furthermore, the data associated with the specific command may be located entirely in the host memory or entirely in the CMB, but not mixed between both the host memory and the CMB. The NVMe standard 1.4 added the PMR, where the previous restrictions made for the NVMe standard 1.3d in regards to the CMB are implemented for the PMR as well. Thus, in the NVMe standard 1.4, data of any command may be located entirely inside the PMR or entirely out of the PMR. If data or data pointers are split between either the CMB and the PMR or the Host and the PMR, then the command will fail. 
     Thus, there is a need in the art to determine if data and data pointers reside either entirely in CMB, entirely in PMR, or in a mixture of at least two of the following: the CMB, the PMR, and the host device. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure generally relates to data storage devices, such as solid state drives (SSDs), specifically utilizing the data storage device memory in the execution of host commands. The host command comprises the command itself (i.e., an instruction to write or read data), pointers to data (e.g., a command pointer), and/or actual data (e.g., data chunks). A controller is configured to receive a command pointer or a data chunk from a host device, mark a destination used for the command pointer or the data chunk, determine whether a last chunk of the command pointers or the data chunk has been received, and determine whether the command pointers or the data chunks use an illegal combination of locations after determining that the last chunk of the command pointer or last data chunk has been received. The controller is further configured to return an error message to the host device upon determining that the command pointers or the data chunks use an illegal combination of locations. 
     In one embodiment, a data storage device includes a memory device and a controller coupled to the memory device. The controller is configured to receive command pointers from a host device, mark a destination used for the command pointers, determine whether a last chunk of the command pointers has been received, and determine whether the command pointers uses an illegal combination of locations after determining that the last chunk of the command pointers has been received. 
     In another embodiment, a data storage device includes a memory device and a controller coupled to the memory device. The controller is configured to receive data chunks associated with a command pointer from a host device, mark a data destination used for the data chunks, determine whether a last chunk of the data chunks has been received, and determine whether the data chunks uses an illegal combination of locations after determining that the last of the chunk of the data chunk has been received. 
     In another embodiment, a data storage device includes memory means, means to transfer data as instructed by a host device, and means to determine, after completing transferring of data as instructed by the host device, whether a mix of locations for the data or pointers is present. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  is a schematic block diagram illustrating a storage system in which data storage device may function as a storage device for a host device, according to certain embodiments. 
         FIG. 2  is a schematic illustration of a write command flow, according to certain embodiments. 
         FIG. 3  is a schematic illustration of a write command flow with a controller memory buffer, according to certain embodiments. 
         FIG. 4  is a schematic block diagram of a read/write command flow diagram, according to certain embodiments. 
         FIG. 5  is a schematic illustration of a data pointer (PRP/SGL) command structure, according to certain embodiments. 
         FIG. 6A  is a schematic illustration of a method of a previous approach to an illegal mixture check, according to certain embodiments. 
         FIG. 6B  is a schematic illustration of a method of an illegal mixture check, according to certain embodiments. 
         FIGS. 7A-7C  are schematic illustrations of a method of detecting scattered data locations, according to certain embodiments. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
     DETAILED DESCRIPTION 
     In the following, reference is made to embodiments of the disclosure. However, it should be understood that the disclosure is not limited to specifically described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the disclosure. Thus, the following aspects, features, embodiments, and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the disclosure” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s). 
     The present disclosure generally relates to data storage devices, such as solid state drives (SSDs), specifically utilizing the data storage device memory in the execution of host commands. A controller is configured to receive a command pointer or a data chunk from a host device, mark a destination used for the command pointer or the data chunk, determine whether a last chunk of the command pointer or the data chunk has been received, and determine whether the command pointer or the data chunk uses an illegal combination of locations after determining that the last chunk of the command pointer has been received. The controller is further configured to return an error message to the host device upon determining that the command pointer or the data chunk uses an illegal combination of locations. 
       FIG. 1  is a schematic block diagram illustrating a storage system  100  in which data storage device  106  may function as a storage device for a host device  104 , according to certain embodiments. For instance, the host device  104  may utilize a non-volatile memory (NVM)  110  included in data storage device  106  to store and retrieve data. The host device  104  comprises a host DRAM  138 . In some examples, the storage system  100  may include a plurality of storage devices, such as the data storage device  106 , which may operate as a storage array. For instance, the storage system  100  may include a plurality of data storage devices  106  configured as a redundant array of inexpensive/independent disks (RAID) that collectively function as a mass storage device for the host device  104 . 
     The host device  104  may store and/or retrieve data to and/or from one or more storage devices, such as the data storage device  106 . As illustrated in  FIG. 1 , the host device  104  may communicate with the data storage device  106  via an interface  114 . The host device  104  may comprise any of a wide range of devices, including computer servers, network attached storage (NAS) units, desktop computers, notebook (i.e., laptop) computers, tablet computers, set-top boxes, telephone handsets such as so-called “smart” phones, so-called “smart” pads, televisions, cameras, display devices, digital media players, video gaming consoles, video streaming device, or other devices capable of sending or receiving data from a data storage device. 
     The data storage device  106  includes a controller  108 , NVM  110 , a power supply  111 , volatile memory  112 , an interface  114 , and a write buffer  116 . In some examples, the data storage device  106  may include additional components not shown in  FIG. 1  for the sake of clarity. For example, the data storage device  106  may include a printed circuit board (PCB) to which components of the data storage device  106  are mechanically attached and which includes electrically conductive traces that electrically interconnect components of the data storage device  106 , or the like. In some examples, the physical dimensions and connector configurations of the data storage device  106  may conform to one or more standard form factors. Some example standard form factors include, but are not limited to, 3.5″ data storage device (e.g., an HDD or SSD), 2.5″ data storage device, 1.8″ data storage device, peripheral component interconnect (PCI), PCI-extended (PCI-X), PCI Express (PCIe) (e.g., PCIe x1, x4, x8, x16, PCIe Mini Card, MiniPCI, etc.). In some examples, the data storage device  106  may be directly coupled (e.g., directly soldered) to a motherboard of the host device  104 . 
     The interface  114  of the data storage device  106  may include one or both of a data bus for exchanging data with the host device  104  and a control bus for exchanging commands with the host device  104 . The interface  114  may operate in accordance with any suitable protocol. For example, the interface  114  may operate in accordance with one or more of the following protocols: advanced technology attachment (ATA) (e.g., serial-ATA (SATA) and parallel-ATA (PATA)), Fibre Channel Protocol (FCP), small computer system interface (SCSI), serially attached SCSI (SAS), PCI, and PCIe, non-volatile memory express (NVMe), OpenCAPI, GenZ, Cache Coherent Interface Accelerator (CCIX), Open Channel SSD (OCSSD), or the like. The electrical connection of the interface  114  (e.g., the data bus, the control bus, or both) is electrically connected to the controller  108 , providing electrical connection between the host device  104  and the controller  108 , allowing data to be exchanged between the host device  104  and the controller  108 . In some examples, the electrical connection of the interface  114  may also permit the data storage device  106  to receive power from the host device  104 . For example, as illustrated in  FIG. 1 , the power supply  111  may receive power from the host device  104  via the interface  114 . 
     The NVM  110  may include a plurality of memory devices or memory units. NVM  110  may be configured to store and/or retrieve data. For instance, a memory unit of NVM  110  may receive data and a message from the controller  108  that instructs the memory unit to store the data. Similarly, the memory unit of NVM  110  may receive a message from the controller  108  that instructs the memory unit to retrieve data. In some examples, each of the memory units may be referred to as a die. In some examples, a single physical chip may include a plurality of dies (i.e., a plurality of memory units). In some examples, each memory unit may be configured to store relatively large amounts of data (e.g., 128 MB, 256 MB, 512 MB, 1 GB, 2 GB, 4 GB, 8 GB, 16 GB, 32 GB, 64 GB, 128 GB, 256 GB, 512 GB, 1 TB, etc.). 
     In some examples, each memory unit of NVM  110  may include any type of non-volatile memory devices, such as flash memory devices, phase-change memory (PCM) devices, resistive random-access memory (ReRAM) devices, magnetoresistive random-access memory (MRAM) devices, ferroelectric random-access memory (F-RAM), holographic memory devices, and any other type of non-volatile memory devices. 
     The NVM  110  may comprise a plurality of flash memory devices or memory units. NVM flash memory devices may include NAND or NOR based flash memory devices and may store data based on a charge contained in a floating gate of a transistor for each flash memory cell. In NVM flash memory devices, the flash memory device may be divided into a plurality of dies, where each die of the plurality of dies includes a plurality of blocks, which may be further divided into a plurality of pages. Each block of the plurality of blocks within a particular memory device may include a plurality of NVM cells. Rows of NVM cells may be electrically connected using a word line to define a page of a plurality of pages. Respective cells in each of the plurality of pages may be electrically connected to respective bit lines. Furthermore, NVM flash memory devices may be 2D or 3D devices and may be single level cell (SLC), multi-level cell (MLC), triple level cell (TLC), or quad level cell (QLC). The controller  108  may write data to and read data from NVM flash memory devices at the page level and erase data from NVM flash memory devices at the block level. 
     The data storage device  106  includes a power supply  111 , which may provide power to one or more components of the data storage device  106 . When operating in a standard mode, the power supply  111  may provide power to one or more components using power provided by an external device, such as the host device  104 . For instance, the power supply  111  may provide power to the one or more components using power received from the host device  104  via the interface  114 . In some examples, the power supply  111  may include one or more power storage components configured to provide power to the one or more components when operating in a shutdown mode, such as where power ceases to be received from the external device. In this way, the power supply  111  may function as an onboard backup power source. Some examples of the one or more power storage components include, but are not limited to, capacitors, supercapacitors, batteries, and the like. In some examples, the amount of power that may be stored by the one or more power storage components may be a function of the cost and/or the size (e.g., area/volume) of the one or more power storage components. In other words, as the amount of power stored by the one or more power storage components increases, the cost and/or the size of the one or more power storage components also increases. 
     The data storage device  106  also includes volatile memory  112 , which may be used by controller  108  to store information. Volatile memory  112  may include one or more volatile memory devices. In some examples, the controller  108  may use volatile memory  112  as a cache. For instance, the controller  108  may store cached information in volatile memory  112  until cached information is written to non-volatile memory  110 . As illustrated in  FIG. 1 , volatile memory  112  may consume power received from the power supply  111 . Examples of volatile memory  112  include, but are not limited to, random-access memory (RAM), dynamic random access memory (DRAM), static RAM (SRAM), and synchronous dynamic RAM (SDRAM (e.g., DDR1, DDR2, DDR3, DDR3L, LPDDR3, DDR4, LPDDR4, and the like)). 
     Furthermore, a portion of the volatile memory  112  may be appropriated to be used by the host device  104 . For example, a controller memory buffer (CMB) may be a portion of the volatile memory  112  stored in or coupled to the controller  108 . In another example, a persistent memory region (PMR) may be a portion of the volatile memory  112  of the data storage device  106 . The CMB and the PMR may span across both SRAM and DRAM or be located in either SRAM or DRAM. Furthermore, in other examples, the CMB and the PMR may be in separate locations of the volatile memory  112 . In other examples, the data storage device  106  may include either the CMB, the PMR, both the CMB and the PMR, or neither the CMB nor the PMR. 
     The data storage device  106  includes a controller  108 , which may manage one or more operations of the data storage device  106 . For instance, the controller  108  may manage the reading of data from and/or the writing of data to the NVM  110 . In some embodiments, when the data storage device  106  receives a write command from the host device  104 , the controller  108  may initiate a data storage command to store data to the NVM  110  and monitor the progress of the data storage command. The controller  108  may determine at least one operational characteristic of the storage system  100  and store the at least one operational characteristic to the NVM  110 . In some embodiments, when the data storage device  106  receives a write command from the host device  104 , the controller  108  temporarily stores the data associated with the write command in the internal memory, such as the volatile memory  112 , or the write buffer  116  before sending the data to the NVM  110 . 
       FIG. 2  is a schematic illustration of a write command flow  200 , according to certain embodiments. A host device, such as the host device  104  of  FIG. 1 , includes a host DRAM, such as the host DRAM  138  of  FIG. 1 . The host device  104  communicates with a data storage device, such as the data storage device  106  of  FIG. 1 , by the way of a data bus. Though the write command flow  200  describes the data flow of a write command between the host device  104  and the data storage device  106 , the command flow may describe the data flow of a read command between the host device  104  and the data storage device  106 . 
     The host device  104  issues a write command to write data with the associated physical region page (PRP) or scatter gather lists (SGLs) to the host DRAM. The host device  104  also places the write command in the submission queue (SQ). It is to be understood that the terms PRPs and SGLs may be used interchangeably. It is also to be understood that for purposes of this disclosure the terms PRPs and SGLs are intended to include alternatively such as would be utilized in NVMe. 
     The host device  104  issues a SQ doorbell to the data storage device  106 . The data storage device  106  responds and reads the command written to the host DRAM  138 . The data storage device  106  receives the write command and reads the relevant PRPs from the host DRAM  138 . The relevant PRPs from the host DRAM  138  are received by the data storage device  106 . The data storage device  106  then reads and receives the data associated with the write command from the host DRAM  138 . After receiving the data from the host DRAM  138 , the data storage device  106  issues a completion notification to the completion queue (CQ) of the host DRAM  138 . 
     The data storage device  106  also sends an interrupt to the host device  104  as an indication that a completion notification has been posted to the host DRAM  138 . The host device  104  then reads and analyzes the relevant completion notification from the host DRAM  138  and issues a CQ doorbell to the data storage device  106 , indicating that the completion notification has been read. The total number of transactions between the host device  104  and the data storage device  106  may be about  10  and the total number of transactions between the host DRAM  138  and the host device  104  may be about  11 . 
       FIG. 3  is a schematic illustration of a write command flow  300  with a controller memory buffer (CMB), according to certain embodiments. Though the write command flow  300  with the CMB describes the data flow of a write command between a host device, such as the host device  104  of  FIG. 1 , and a data storage device, such as the data storage device  106  of  FIG. 1 , the command flow may describe the data flow of a read command between the host device  104  and the data storage device  106 . Furthermore, in some embodiments, it is contemplated that the write command flow  300  or the similarly contemplated read command flow may be utilized with the persistent memory region (PMR) or with both the PMR and the CMB. 
     The host device  104  issues a write command to write data with the associated PRPs. Rather than writing to a host DRAM, such as the host DRAM  138  of  FIG. 1 , the data storage device  106  includes a CMB functionality to provide access for the host device  104  a portion of the DRAM of the data storage device  106 . In certain embodiments, the CMB may be included in the controller, such as the controller  108  of  FIG. 1 , of the data storage device  106 . For example, in the write command flow  200  of  FIG. 2 , the write command is written to the host DRAM  138 , where the data storage device  106  reads from the host DRAM  138 . Referring to  FIG. 3 , rather than writing the command to the host DRAM  138 , the write command is written to CMB. 
     In the write command flow  300  with the CMB, the host device  104  writes the write command and the relevant PRPs to the CMB of the data storage device  106 . The host device  104  then fills the write command in the SQ. The host device  104  issues a SQ doorbell to the data storage device  106 . The data storage device  106  then reads the write command with the associated PRPs and data from the CMB. The data storage device  106  writes a completion notification to the CQ of the CMB. An interrupt is sent to the host device  104 . When the host device  104  receives the interrupt, the host device  104  reads and receives the completion notification from the CQ of the CMB. 
     The host device  104  then issues a CQ doorbell to the data storage device  106 , indicating that the completion notification has been read. Because the data is written to the CMB of the data storage device  106 , the number of transactions and the time associated with the transactions between the host device  104  and the data storage device  106  may be reduced, thus speeding the process of a read or write command. For example, the total number of transactions between the host device  104  and the data storage device  106  may be about 8 and the total number of transactions between the CMB and the data storage device  106  may be about 9. Thus, by using the CMB functionality of the data storage device  106 , as described in  FIG. 3 , better performance and lower latency may be achieved due to less crosses between the host device  104  and the data storage device when compared to the write command flow  200  of  FIG. 2 . 
       FIG. 4  is a schematic block diagram of a read/write command flow diagram  400 , according to certain embodiments. The read/write command flow diagram  400  may be an implementation of executing read or write commands sent by a host, such as the host device  104  of  FIG. 1 , within a data storage device, such as the data storage device  106  of  FIG. 1 . The read/write command flow diagram  400  includes or utilizes different components of the data storage device  106 . For example, the read/write command flow diagram  400  includes an interface  402  and a control  404 . The interface  402  may be the interface  114  of  FIG. 1  and the control  404  may be the controller  108  of  FIG. 1 . The dashed lines indicate a command flow, where the command flow includes a destination address. The dotted lines indicate a response flow, where the response flow includes an error. 
     In order for the controller  108  to determine that a PRP/SGL resides in either the CMB  420  or the PMR  422  and not on the host device memory, such as the host DRAM  138  of  FIG. 1 , the addresses of the pointers of the PRP/SGL should point to a memory range that belongs to either the CMB  420  or the PMR  422 . Likewise, in order for the controller  108  to determine that data resides in the CMB  420  or the PMR  422 , and not the host DRAM  138 , the addresses in the PRP/SGL points to a memory range that belongs to either the CMB  420  or the PMR  422 . The host device  104  provides the address range for the CMB  420  and the address range for the PMR  422  to the controller  108 . The controller  108  reads the PRP/SGL in order to read or write data to a location in the NVM, such as the NVM  110  of  FIG. 1 . 
     When the control  404  receives a read or write command from the host device  104 , the control  404  is responsible for gathering information on the success or failure of the read or write command. The control  404  interacts with a data read direct memory access (DMA)  406 , a PRP/SGL fetching module  408 , and a data write DMA  410 . The data read DMA  406  is used to read data due to host write commands from the host device  104 . The data write DMA  410  is used to write data due to host read commands from the host device  104 . Because the PRP/SGL resides in either the CMB  420  or the PMR  422 , the PRP/SGL fetching module  408  is utilized to read the PRP/SGL from the respective in the location in the CMB  420  or the PMR  422 . 
     The read gateway  412  and the write gateway  414  each receives requests from the respective data read DMA  406 , the PRP/SGL fetching module  408 , and the data write DMA  410 . The read gateway  412  and the write gateway  414  interacts with an outbound translation module  416  to determine the destination for the received request, where the destination is based on the address. The read gateway  412  and the write gateway  414  passes the request to the appropriate destination and, in return, receives responses. When the read gateway  412  and the write gateway  414  receives the responses, the responses are routed to the appropriate originating read flow or write flow (i.e., the data read DMA  406 , the PRP/SGL fetching module  408 , or the data write DMA  410 ). 
     The read gateway  412  and the write gateway  412  interacts with a routing module  418  to route the PRP/SGL and/or data to the appropriate location in either the CMB  420  or the PMR  422 . The routing module  418  may be an internal routing matrix that directs transactions from the read gateway  412  and the write gateway  414  to the CMB  420  and the PMR  422 . Furthermore, the read gateway  412  and the write gateway  414  interacts with the interface  402  to provide data to the host device  104 . 
       FIG. 5  is a schematic illustration of a data pointer (PRP/SGL) command structure  500 , according to certain embodiments. The data pointer command structure  500  shows that the data is divided into five areas. The first area  502  and the fourth area  508  are located in the PMR, such as the PMR  422  of  FIG. 4 . The second area  504  and the third area  506  are located in the host device, such as the host device  104  of  FIG. 1 . The fifth area  510  is located in the CMB, such as the CMB  420  of  FIG. 4 . Because the data pointer command structure  500  is split between the PMR  422  and the CMB  420 , an error is detected and reported to the host device  104  when the command associated with the data pointer command structure  500  is executed. 
       FIG. 6A  is a schematic illustration of a method  600  of a previous approach to an illegal mixture check, according to certain embodiments. The method  600  begins at block  602  when the controller, such as the controller  108  of  FIG. 1 , receives a host request to read data or write data to the internal memory, such as the CMB  420  or the PMR  422  of  FIG. 4 . At block  604 , all the relevant data pointers (i.e., PRP/SGL) are fetched from their relevant locations. After receiving the relevant data pointers at block  604 , the controller, such as the controller  108  of  FIG. 1 , or the control, such as the control  404 , determines whether received data pointers include an illegal mixture at block  606 . An illegal mixture includes data pointers pointing to at least two of the following locations: the CMB  420 , the host DRAM, such as the host DRAM  138  of  FIG. 1 , and the PMR  422 . 
     If an illegal mixture is present at block  606 , then the transfer is aborted at block  608  and an error completion message  610  is returned to the host device  104 . However, if the illegal mixture is not present at block  606 , such that the data pointers are located either entirely in the CMB  420 , in the host DRAM  138 , or in the PMR  422 , then at block  612 , the data is transferred to the respective location (i.e., the destination of the read or write command). At block  614 , the method  600  is completed as normal. 
       FIG. 6B  is a schematic illustration of a method  650  of an illegal mixture check, according to certain embodiments. The method  650  begins at block  652  when the controller, such as the controller  108  of  FIG. 1 , receives a host request to read data or write data to the internal memory, such as the CMB  420  or the PMR  422  of  FIG. 4 . At block  654 , all the relevant data pointers (i.e., PRP/SGL) are fetched from their relevant locations. After receiving the relevant data pointers at block  654 , the relevant data is transferred to the respective location (i.e., destination of the read or write command) at block  656 . 
     At block  658 , the controller  108  or the control  404  determines if the data pointers includes an illegal mixture. If the data pointers includes the illegal mixture, then at block  660 , an error completion message is returned to the host device  104 . However, if the data pointers do not include the illegal mixture, then the method  650  is completed as normal at block  662 . Unlike method  600 , the decision or the determination if the data pointers includes an illegal mixture occurs after the data is transferred at block  656 . By including the illegal mixture check after the data is transferred, previous command flows are not interrupted and the illegal mixture check may be implemented to the previous command flows. 
     It is contemplated that while methods  600  and  650  describe detecting an illegal mixture of data chunks, the methods  600  and  650  may be applicable to detecting an illegal mixture of data pointers. 
       FIGS. 7A-7C  are schematic illustrations of a method  700  of detecting scattered data locations, according to certain embodiments. Aspects of the method  700  may be similar to aspects of the method  650 . 
     Referring to  FIG. 7A , the method  700  includes a data pointers: address phase  704 , a data pointers: response phase  706 , a data pointers: check phase, a data: address phase  716 , a data: response phase  718 , and a data: check phase. The method  700  starts at block  702 , where the data storage device, such as the data storage device  106  of  FIG. 1 , receives a read or write command from a host device, such as the host device  104  of  FIG. 1 . After receiving the read or write command from the host device  104 , the method  700  advances to the data pointers: address phase  704  and subsequently, the data pointers: response phase  706 . The data pointers: address phase  704  and the data pointers: response phase  706  will be described in greater detail in the description of  FIG. 7B . 
     At the data pointers: check phase, the controller, such as the controller  108  of  FIG. 1 , marks the destination at block  708 . The destination is the data pointer location of the received read or write command. In some examples, the data pointer may be referred to as command pointer. At block  710 , the controller, determines if the received destination corresponds with the last chunk of the data pointers. If the last chunk of the data pointers has not been received, then the method  700  returns to the data pointers: address phase  704 . However, if the last chunk of the data pointers has been received, then the controller  108  determines if the data pointers includes an illegal mixture (i.e., both CMB and PMR) at block  712 . If the data pointers do include the illegal mixture at block  712 , then at block  714  the method  700  ends with an error (i.e., returns an error message to the host device). However, if the data pointers do not include the illegal mixture at block  712 , then the method  700  proceeds to the data: address phase  716  and subsequently to the data: response phase  718 . The data pointers: address phase  716  and the data pointers: response phase  718  will be described in greater detail in the description of  FIG. 7C . 
     At the data: check phase, the controller  108  marks the destination at block  720 . The destination is the data location of the received read or write command. At block  722 , the controller, determines if the received destination corresponds with the last chunk of the data. If the last chunk of the data has not been received, then the method  700  returns to the data: address phase  716 . However, if the last chunk of the data has been received, then the controller  108  determines if the data includes an illegal mixture (i.e., both CMB and PMR) at block  724 . If the data does include the illegal mixture at block  724 , then at block  726  the method  700  ends with an error (i.e., returns an error message to the host device). However, if the data pointers do not include the illegal mixture at block  724 , then the method  700  successfully ends at block  728  with a completion notification and interrupt message to the host device  104 . 
     Regarding the data pointers: address phase  704  and the data: address phase  716 , the phases begin at blocks  732  and  762 . At blocks  732  and  762 , the controller receives a request to fetch data pointers or data, respectively. At block  734 , the PRP/SGL fetch, such as the PRP/SGL fetching module  408  of  FIG. 4 , sends the transaction to the data gateway or gateway, such as the appropriate read gateway  412  or write gateway  414  of  FIG. 4 . Likewise, at block  764 , the relevant DMA, such as the read DMA  406  or the write DMA  410  of  FIG. 4 , sends the transaction to the relevant read gateway  412  or write gateway  414 . At blocks  736  and  766 , the controller determines if the gateway is ready. If the gateway is not ready, the method  700  loops at blocks  736  and  766  until the gateway is ready. 
     However, if the gateway is ready at block  736  and  766 , the gateway remembers who did the request at blocks  738  and  768 . At blocks  740  and  770 , the gateway requests an address translation. At blocks  742  and  772 , the address translation and destination are sent to the gateway. At blocks  744  and  774 , the gateway remembers the destination. After remembering the destination at blocks  744  and  774 , the method  770  proceeds to the data pointers: response phase  706  and the data: response phase  718 . 
     At blocks  746  and  776 , the controller determines if the response has arrived to the gateway. If the response has not arrived to the gateway, the method  700  loops at blocks  746  and  776  until the response arrives to the gateway. When the response arrives to the gateway in the data pointers: response phase  706 , the response and destination are returned to the PRP/SGL fetcher at block  748 . Likewise, when the response arrives to the gateway in the data: response phase  718 , the response and destination are returned to the relevant read DMA  406  or the write DMA  410 . At blocks  750  and  780 , the response and destination are returned to the controller. At block  750 , the method  700  continues to block  708  and at block  780 , the method  700  continues to block  720 . 
     In some examples, the method  700  may be used separately for data pointers or for data. For example, only the data pointer: check phase or the data: check phase is utilized. In another example, the data pointers may be held in one location, such as the CMB, and the data may be held in another location, such as the PMR. 
     By implementing an illegal mixture check at the completion of the read/write command flow, the detection of scattered data locations may be added efficiently to current read/write command flows. 
     In one embodiment, a data storage device includes a memory device and a controller coupled to the memory device. The controller is configured to receive command pointers from a host device, mark a destination used for the command pointers, determine whether a last chunk of the command pointers has been received, and determine whether the command pointers uses an illegal combination of locations after determining that the last chunk of the command pointers has been received. 
     The controller is configured to determine that the command pointers uses an illegal combination of locations and return an error message to the host device. The controller is configured to determine that the command pointers does not use an illegal combination of locations and start a data address phase operation for command data associated with the command pointers. The data address phase operation comprises reading data chunks or writing data chunks to the memory device. The controller is further configured to mark a data destination used for the data address phase operation, where the data destination is received from a data response phase operation, determine whether a last chunk of the command data has been received, and determine whether the command data uses the illegal combination of locations after determining that the last chunk of the command data has been received. The data response phase operation includes receiving a data response from a data gateway and returning the data response and data destination. The command pointer has a command structure comprising a plurality of areas, wherein each area of the plurality of areas is either a PMR area, a host device area, or a CMB area. The controller further includes a control unit, a data read DMA coupled to the control unit, a PRP/SGL fetching unit coupled to the control unit, and a data write DMA coupled to the control unit. The controller is further configured to determine that a response has arrived at a read or write gateway, return the response and destination to the PRP/SGL fetching unit, and return the response and destination to the control unit. 
     In another embodiment, a data storage device includes a memory device and a controller coupled to the memory device. The controller is configured to receive data chunks associated with a command pointer from a host device, mark a data destination used for the data chunks, determine whether a last chunk of the data chunks has been received, and determine whether the data chunks uses an illegal combination of locations after determining that the last chunk of the data chunks has been received. 
     The controller is further configured to read data or write data from the memory device after determining that the last chunk of the data chunk has not been received. The illegal combination of locations comprises a first location from a controller memory buffer, a persistent memory region, or a host location and a second location from a controller memory buffer, a persistent memory region, or a host location, and where the first location and the second location are different. The controller is further configured to mark the command as completed without an error upon determining that the data chunks does not use the illegal combination of locations. The controller is further configured to mark the command as completed with an error upon determining that the data chunks uses the illegal combination of locations. The marking the data destination used for the data chunk includes determining that a data response has arrived at a read or write gateway, returning the data response and data destination to a PRP/SGL fetching unit, and returning the data response and data destination to the controller. The read or write gateway comprises logic to remember an initiator of the data chunk. An address of the data chunk is translated and the data destination is transferred to the gateway, where the address includes one or more locations associated with the data chunk, and where the one or more locations includes at least one of a CMB, a PMR, or a host. 
     In another embodiment, a data storage device includes memory means, means to transfer data as instructed by a host device, and means to determine, after completing transferring of data as instructed by the host device, whether a mix of locations for the data is present. 
     The data storage device further includes a data read DMA, a PRP/SGL fetching unit, and a data write DMA. The means to determine whether a mix of location for the data is present includes means to determine whether data pointers for the data use an illegal combination of locations. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.