System and method for persistent RAM disk
The contents of a RAM disk are copied to an image file in nonvolatile memory on power-down and copied back on reboot to provide an appearance of persistence. A locking method can use in-use tables to limit access to the same blocks of data in a RAM disk.
1. A method for restoring a RAM disk in a volatile storage device from a corresponding image file on a nonvolatile storage device while the RAM disk is being populated, during or approximately at the time of operating system boot-up, the method comprising:
creating a RAM disk in the volatile storage device corresponding to an image file in the nonvolatile storage device;
writing data from the image file to the RAM disk; and asynchronously and substantially simultaneously accessing both the image file on the nonvolatile storage device and the RAM disk on the volatile storage device so that the two storage devices are available to the operating system during system boot-up;
wherein both the image file on the nonvolatile storage device and on the RAM disk are available to the operating system in combination for access during both system boot-up or subsequent shutdown, before the RAM disk is fully populated from the image file.
2. The method of claim 1 , further comprising maintaining the image file in a viable state for backup purposes at least until the RAM disk is fully restored.
3. The method of claim 2 , wherein after the RAM disk is fully populated from the image file after system boot-up, the RAM disk contains the same information the RAM disk had during system shut-down.
4. The method of claim 1 , further comprising writing-through data from the RAM disk to the nonvolatile storage device when the RAM disk is in use for both read and write operations.
5. The method of claim 1 , wherein both the image file on the nonvolatile storage device and the RAM disk on the volatile storage device are available to the operating system after system boot-up.
6. The method of claim 1 , wherein the operating system is allowed access to information belonging in the RAM disk, wherein the information:
(i) is already loaded into the RAM disk on the volatile storage device; or
(ii) physically resides in the image file on the nonvolatile storage device pending loading into the RAM disk.
7. The method of claim 1 , wherein the RAM disk is populated from the image file in response to a system boot-up.