SELF-VIRTUALIZING FLASH MEMORY FOR SOLID STATE DRIVE

• US 20180129440A1
• Filed: 11/09/2016
• Published: 05/10/2018
• Est. Priority Date: 11/09/2016
• Status: Abandoned Application

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Bandic, Zvonimir Z., Song, Seung-Hwan, Sun, Chao, Qin, Minghai, Vucinic, Dejan
• Application Number:
  US15/347,472
• Publication Number:
  US 20180129440A1
• Time in Patent Office: Days
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0634 by changing the state or mode of one or more devices
• CPC Class Codes: G06F 3/0667 at data level, e.g. file, record or object virtualisation
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

In general, a controller may perform a self-virtualization technique. The storage device may include storage access comprising multiple cells, and a controller. The controller may determine a maximum amount of storage access for a virtual machine workload when each cell is configured in a first level mode having a maximum allowable number of bits per cell. The controller may configure each cell to be in a second level mode having a number of bits per cell less than the maximum. The controller may determine a total number of bits in use in each cell and compare this total to a threshold number of bits in use in each cell. Based on the comparison, the controller may reconfigure one or more cells to be in a third level mode having a number of bits per cell greater than the number for the second level mode.

Claims

1. A method comprising:

determining, by a controller, a maximum amount of storage access for a virtual machine workload on a solid state drive (SSD) when each cell in the storage access is configured in a first level mode having a maximum allowable number of bits per cell;

configuring, by the controller, each of the cells in the storage access for the virtual machine to be in a second level mode having a number of bits per cell less than the maximum allowable number of bits per cell;

determining, by the controller, a total number of bits in use in each of the cells of the storage access;

comparing, by the controller, the total number of bits in use in each of the cells of the storage access to a threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfiguring, by the controller, one or more of the cells in the storage access for the virtual machine to be in a third level mode having a number of bits per cell greater than the number of bits per cell for the second level mode.

2. The method of claim 1, wherein the first level mode comprises a triple-level cell (TLC) mode, wherein the maximum allowable number of bits per cell is equal to three bits per cell, wherein the second level mode comprises a single-level cell (SLC) mode, wherein the number of bits per cell for the SLC mode is one bit per cell, wherein the third level mode comprises a multiple-level cell (MLC) mode, wherein the number of bits per cell for the MLC mode is two bits per cell,

wherein the storage access comprises a first storage access, wherein configuring each of the cells in the first storage access to be in the second level mode comprises initially configuring each of the cells in the first storage access to be in the SLC mode,

and wherein the method further comprises:

initially configuring, by the controller, a second storage access of the SSD to be in the MLC mode, wherein the second storage access is associated with a second virtual machine workload; and

initially configuring, by the controller, a third storage access of the SSD to be in the TLC mode, wherein the third storage access is associated with a third virtual machine workload,

wherein reconfiguring the first storage access comprises;

responsive to determining that the number of bits in use in each of the cells in the first storage access exceeds the threshold number of bits, reconfiguring, by the controller, each of the cells in the first storage access to be in the MLC mode.

3. The method of claim 1, wherein the first level mode comprises a triple-level cell (TLC) mode, wherein the maximum allowable number of bits per cell is equal to three bits per cell, wherein the second level mode comprises a single-level cell (SLC) mode, wherein the number of bits per cell for the SLC mode is one bit per cell, wherein the third level mode comprises a multiple-level cell (MLC) mode, and wherein the number of bits per cell for the MLC mode is two bits per cell.

4. The method of claim 3, wherein the threshold number of bits in use comprises a first threshold number of bits, the method further comprising:

comparing, by the controller, the total number of bits in use in each of the cells of the storage access to a second threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfiguring, by the controller, one or more cells in the storage access for the virtual machine to be in the first level mode having the maximum allowable number of bits per cell.

5. The method of claim 1, wherein the virtual machine comprises a first virtual machine, the method further comprising:

determining, by the controller, a maximum amount of storage access for a second virtual machine on the SSD when each of the cells in the storage access is configured in the first level mode; and

configuring, by the controller, each of the cells in the storage access for the second virtual machine to be in the third level mode.

6. The method of claim 5, further comprising:

receiving, by the controller, a request from a host device to access the SSD;

determining, by the controller, a guest level for the host device; and

assigning, by the controller, the host device to one of the first virtual machine or the second virtual machine based at least in part on the guest level for the host device.

7. The method of claim 1, wherein reconfiguring the one or more cells comprises:

receiving, by the controller, a request to write data to the storage access;

determining, by the controller, a number of cells required to be in the third level mode in order for the controller to write the received data to the storage access; and

reconfiguring, by the controller, the determined number of cells in the storage access to be in the third level mode.

8. The method of claim 1, wherein reconfiguring the one or more cells comprises:

reconfiguring, by the controller, the entirety of the storage access to be in the third level mode.

9. The method of claim 1, wherein the first level mode comprises a quad-level cell (QLC) mode having the maximum allowable number of bits per cell of four bits per cell, wherein the second level mode comprises a single-level cell (SLC) mode having one bit per cell, wherein the third level mode comprises a multiple-level cell (MLC) mode having two bits per cell, wherein the threshold number of bits in use comprises a first threshold number of bits, and wherein the method further comprises:

comparing, by the controller, the total number of bits in use in each of the cells of the storage access to a second threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfiguring, by the controller, one or more cells in the storage access for the virtual machine to be in a fourth level mode having a number of bits per cell greater than the number of bits per cell for the third level mode.

10. The method of claim 9, wherein the fourth level mode comprises a triple-level cell (TLC) mode having three bits per cell, and wherein the method further comprises:

comparing, by the controller, the total number of bits in use in each of the cells of the storage access to a third threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfiguring, by the controller, one or more cells in the storage access for the virtual machine to be in the first level mode having the maximum allowable number of bits per cell.

11. The method of claim 1, wherein reconfiguring the one or more cells comprises:

reconfiguring, by the controller, the one or more cells during a garbage collection process.

12. The method of claim 1, wherein the storage access comprises a first storage access, wherein the SSD comprises a plurality of blocks, wherein the method further comprises:

initially configuring, by the controller, the first storage access comprising a first portion of each block of the plurality of blocks to be in the first level mode, wherein the first storage access is associated with a first virtual machine workload;

initially configuring, by the controller, a second storage access comprising a second portion of each block of the plurality of blocks to be in the second level mode, wherein the second storage access is associated with a second virtual machine workload; and

initially configuring, by the controller, a third storage access comprising a third portion of each block of the plurality of blocks to be in the third level mode, wherein the third storage access is associated with a third virtual machine workload.

13. The method of claim 1, wherein reconfiguring the one or more cells comprises:

reconfiguring, by the controller, the one or more cells as part of a single root input/output virtualization process.

14. A storage device comprising:

a storage access comprising a plurality of cells; and

a controller configured to;

determine a maximum amount of storage access for a virtual machine workload when each of the cells in the storage access is configured in a first level mode, wherein each of the cells in the storage access being configured in the first level mode comprises each of the cells in the storage access having a maximum allowable number of bits per cell;

configure each of the cells in the storage access for the virtual machine to be in a second level mode, wherein each of the cells in the storage access being configured in the second level mode comprises each of the cells in the storage access having a number of bits per cell less than the maximum allowable number of bits per cell;

determine a total number of bits in use in each of the cells of the storage access;

compare the total number of bits in use in each of the cells of the storage access to a threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfigure one or more cells in the storage access for the virtual machine to be in a third level mode, wherein the one or more cells in the storage access being configured in the third level mode comprises each of the cells in the storage access having a number of bits per cell greater than the number of bits per cell for the second level mode.

15. The storage device of claim 14, wherein the first level mode comprises a triple-level cell (TLC) mode, wherein the maximum allowable number of bits per cell is equal to three bits per cell, wherein the second level mode comprises a single-level cell (SLC) mode, wherein the number of bits per cell for the SLC mode is one bit per cell, wherein the third level mode comprises a multiple-level cell (MLC) mode, wherein the number of bits per cell for the MLC mode is two bits per cell, wherein the threshold number of bits in use comprises a first threshold number of bits, and wherein the controller is further configured to:

compare the total number of bits in use in each of the cells of the storage access to a second threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfigure one or more cells in the storage access for the virtual machine to be in the first level mode, wherein the one or more cells in the storage access being configured in the first level mode comprises each of the cells in the storage access having the maximum allowable number of bits per cell.

16. The storage device of claim 14, wherein the virtual machine comprises a first virtual machine, wherein the controller is further configured to:

determine a maximum amount of storage access for a second virtual machine on the SSD when each of the cells in the storage access is configured in the first level mode;

configure each of the cells in the storage access for the second virtual machine to be in the third level mode;

receive a request from a host device to access the SSD;

determine a guest level for the host device; and

assign the host device to one of the first virtual machine or the second virtual machine based at least in part on the guest level for the host device.

17. The storage device of claim 14, wherein the first level mode comprises a quad-level cell (QLC) mode, wherein the maximum allowable number of bits per cell for the QLC mode is equal to four bits per cell, wherein the second level mode comprises a single-level cell (SLC) mode, wherein the number of bits per cell for the SLC mode is one bit per cell, wherein the third level mode comprises a multiple-level cell (MLC) mode, wherein the number of bits per cell for the MLC mode is two bits per cell, wherein the threshold number of bits in use comprises a first threshold number of bits, and wherein the controller is further configured to:

compare the total number of bits in use in each of the cells of the storage access to a second threshold number of bits in use in each of the cells of the storage access;

based on the comparison, reconfigure one or more cells in the storage access for the virtual machine to be in a fourth level mode, wherein the one or more cells in the storage access being configured in the fourth level mode comprises each of the cells in the storage access having a number of bits per cell greater than the number of bits per cell for the third level mode, wherein the fourth level mode comprises a triple-level cell (TLC) mode, and wherein the number of bits per cell for the TLC mode is three bits per cell;

compare the total number of bits in use in each of the cells of the storage access to a third threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfigure one or more cells in the storage access for the virtual machine to be in the first level mode, wherein the one or more cells in the storage access being configured in the first level mode comprises each of the cells in the storage access having the maximum allowable number of bits per cell.

18. The storage device of claim 14, wherein the storage access comprises a first storage access, wherein the SSD comprises a plurality of blocks, wherein the controller is further configured to:

initially configure the first storage access comprising a first portion of each block of the plurality of blocks to be in the first level mode, wherein the first storage access is associated with a first virtual machine workload;

initially configure a second storage access comprising a second portion of each block of the plurality of blocks to be in the second level mode, wherein the second storage access is associated with a second virtual machine workload; and

initially configure a third storage access comprising a third portion of each block of the plurality of blocks to be in the third level mode, wherein the third storage access is associated with a third virtual machine workload.

19. A computer-readable storage medium storing instructions that, when executed, cause a controller of a storage device to:

determine a maximum amount of storage access for a virtual machine workload on a solid state drive (SSD) when each of the cells in the storage access is configured in a first level mode, wherein each of the cells in the storage access being configured in the first level mode comprises each of the cells in the storage access having a maximum allowable number of bits per cell;

configure each of the cells in the storage access for the virtual machine to be in a second level mode, wherein each of the cells in the storage access being configured in the second level mode comprises each of the cells in the storage access having a number of bits per cell less than the maximum allowable number of bits per cell;

determine a total number of bits in use in each of the cells of the storage access,

compare the total number of bits in use in each of the cells of the storage access to a threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfigure one or more cells in the storage access for the virtual machine to be in a third level mode, wherein the one or more cells in the storage access being configured in the third level mode comprises each of the cells in the storage access having a number of bits per cell greater than the number of bits per cell for the second level mode.

20. The computer-readable storage medium of claim 19, wherein the first level mode comprises a triple-level cell (TLC) mode, wherein the maximum allowable number of bits per cell is equal to three bits per cell, wherein the second level mode comprises a single-level cell (SLC) mode, wherein the number of bits per cell for the SLC mode is one bit per cell, wherein the third level mode comprises a multiple-level cell (MLC) mode, wherein the number of bits per cell for the MLC mode is two bits per cell, wherein the threshold number of bits in use comprises a first threshold number of bits, and wherein instructions further cause the controller to:

compare the total number of bits in use in each of the cells of the storage access to a second threshold number of bits in use in each of the cells of the storage access; and

based on the comparison, reconfigure one or more cells in the storage access for the virtual machine to be in the first level mode, wherein the one or more cells in the storage access being configured in the first level mode comprises each of the cells in the storage access having the maximum allowable number of bits per cell.