Storage device out-of-space handling

1. A method of detecting, by a media controller coupled to a host device and a solid-state media, an impending out-of-space (OOS) condition of the solid-state media, the solid-state media having a physical storage capacity, the method comprising:

on startup of the media controller:

determining, by the media controller, whether an impending OOS indicator of the solid-state media is set from a previous startup of the media controller;

if the impending OOS indicator is not set:

determining, whether an OOS condition of the solid-state media has occurred, by determining whether a free pool size of the solid-state drive has reached a first threshold, wherein the free pool comprises blocks of the solid-state media available to be written with data;

if the OOS condition of the solid-state media has occurred:

setting the impending OOS indicator and operating the solid-state media in an impending OOS operation mode;

otherwise, if the OOS condition has not occurred:

operating the solid-state media in a normal operation mode;

wherein, the normal operation mode comprises:

checking, periodically, whether the free pool size of the solid-state drive becomes less than a second threshold and, if so:

operating the solid-state media in a write stall operation mode, wherein, in the write stall operation mode, the media controller limits write operations from the host device to the solid-state media to a predetermined, non-zero, maximum data throughput, thereby preserving free space on the solid-state media; and

if the free pool size has not reached the first threshold:

while a current startup time of the media controller is less than a maximum startup time, performing garbage collection on the solid-state media to accumulate additional blocks to the free pool;

if the current startup time reaches the maximum startup time and the free pool size has not reached the first threshold:

setting the impending OOS indicator and operating the solid-state media in the impending OOS operation mode;

otherwise, if the free pool size reaches or exceeds the first threshold:

operating the solid-state media in the normal operation mode.

2. The method of claim 1 , wherein the first threshold is 1% of the physical storage capacity of the solid-state media.

3. The method of claim 1 , further comprising:

if the impending OOS indicator of the solid-state media is set from a previous startup of the media controller:

determining whether used space of the solid-state media is below a safe threshold and, if so:

clearing the impending OOS indicator;

otherwise:

maintaining the impending OOS indicator and operating the solid-state media in the impending OOS operation mode.

4. The method of claim 3 , wherein the safe threshold is 95% of the physical storage capacity of the solid-state media.

5. The method of claim 1 , wherein the predetermined maximum data throughput is 100 KB/sec.

6. The method of claim 1 , wherein write operations are limited to a predetermined data size.

7. The method of claim 1 , further comprising, during the write stall operation mode:

checking, periodically, whether the free pool size of the solid-state drive remains less than a second threshold and, if so:

continuing operating the solid-state media in a write stall operation mode;

otherwise:

operating the solid-state media in the normal operation mode.

8. The method of claim 1 , further comprising, during the write stall operation mode:

restarting the host device and media controller.

9. The method of claim 1 , wherein the second threshold is a write stall limit of the solid-state media, and the write stall limit is 0.9% of the physical storage capacity of the solid-state media.

10. The method of claim 1 , further comprising:

notifying the host device that the solid-state media is operating in the impending OOS operation mode.

11. The method of claim 10 , wherein, in response to receiving the notification that the solid-state media is operating in the impending OOS operation mode, the host device provides a notification to a user of the host device.

12. The method of claim 11 , further comprising:

receiving, by the host device, commands from the user to delete data from the solid-state media; and

sending, by the host device, a TRIM command to the media controller; and

in response to the TRIM command, erasing, by the media controller, one or more blocks of the solid-state media.

13. The method of claim 1 , wherein the impending OOS indicator is persistently stored in a root file system of the solid-state media.

14. A non-transitory machine-readable medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method of detecting, by a media controller coupled to a host device and a solid-state media, an impending out-of-space (OOS) condition of the solid-state media, the solid-state media having a physical storage capacity, the method comprising:

on startup of the media controller:

determining, by the media controller, whether an impending OOS indicator of the solid-state media is set from a previous startup of the media controller;

if the impending OOS indicator is not set:

determining, by the media controller, whether a free pool size of the solid-state drive has reached a first threshold, wherein the free pool comprises blocks of the solid-state media available to be written with data;

if the free pool size has not reached the first threshold:

while a current startup time of the media controller is less than a maximum startup time, performing garbage collection on the solid-state media to accumulate additional blocks to the free pool;

if the current startup time reaches the maximum startup time and the free pool size has not reached the first threshold:

 setting the impending OOS indicator and operating the solid-state media in an impending OOS operation mode;

otherwise, if the free pool size reaches or exceeds the first threshold:

 operating the solid-state media in a normal operation mode; and

during the normal operation mode:

checking, periodically, whether the free pool size of the solid-state drive becomes less than a second threshold and, if so:

operating the solid-state media in a write stall operation mode, wherein, in the write stall operation mode, the media controller limits write operations from the host device to the solid-state media to a predetermined, non-zero, maximum data throughput, thereby preserving free space on the solid-state media; and

if the free pool size has not reached the first threshold:

while a current startup time of the media controller is less than a maximum startup time, performing garbage collection on the solid-state media to accumulate additional blocks to the free pool;

if the current startup time reaches the maximum startup time and the free pool size has not reached the first threshold:

setting the impending OOS indicator and operating the solid-state media in the impending OOS operation mode;

otherwise, if the free pool size reaches or exceeds the first threshold:

operating the solid-state media in the normal operation mode.

15. The non-transitory machine-readable medium of claim 14 , further comprising:

if the impending OOS indicator of the solid-state media is set from a previous startup of the media controller:

determining whether used space of the solid-state media is below a safe threshold and, if so:

clearing the impending OOS indicator;

otherwise:

maintaining the impending OOS indicator and operating the solid-state media in the impending OOS operation mode.

16. A media controller for a solid-state media having a physical storage capacity, the media controller configured to detect an impending out-of-space (OOS) condition of the solid-state media, the media controller comprising:

an input/output interface configured to communicate with a host device coupled to the media controller;

a control processor coupled to the input/output interface, the control processor configured to, on startup of the media controller:

determine whether an impending OOS indicator of the solid-state media is set from a previous startup of the media controller;

if the impending OOS indicator is not set:

determine whether a free pool size of the solid-state drive has reached a first threshold, the free pool comprising blocks of the solid-state media available to be written with data;

if the free pool size has not reached the first threshold:

while a current startup time of the media controller is less than a maximum startup time, perform garbage collection on the solid-state media to accumulate additional blocks to the free pool;

if the current startup time reaches the maximum startup time and the free pool size has not reached the first threshold:

 set the impending OOS indicator and operate the solid-state media in an impending OOS operation mode;

otherwise, if the free pool size reaches or exceeds the first threshold:

 operate the solid-state media in a normal operation mode;

if the impending OOS indicator of the solid-state media is set from a previous startup of the media controller:

determine whether used space of the solid-state media is below a safe threshold and, if so: clear the impending OOS indicator;

otherwise: maintain the impending OOS indicator and operate the solid-state media in the impending OOS operation mode;

check, periodically during normal operation mode, whether the free pool size of the solid-state drive becomes less than a second threshold and, if so:

operate the solid-state media in a write stall operation mode, wherein, in the write stall operation mode, the media controller limits write operations from the host device to the solid-state media to a predetermined, non-zero, maximum data throughput, thereby preserving free space on the solid-state media; and

if the free pool size has not reached the first threshold:

while a current startup time of the media controller is less than a maximum startup time, performing garbage collection on the solid-state media to accumulate additional blocks to the free pool;

if the current startup time reaches the maximum startup time and the free pool size has not reached the first threshold:

setting the impending OOS indicator and operating the solid-state media in the impending OOS operation mode;

otherwise, if the free pool size reaches or exceeds the first threshold:

operating the solid-state media in the normal operation mode.