RamDisk 2000 2003 FAQ

Q: The answer to this question depends on how many CPUs you have in your system, how much memory you have and the type of applications you are running. The faster or greater the CPU power, the faster you can access data from SuperCache-NT or SuperSpeed-NT. Having plenty of memory can also help.

AIt is not unusual for I/O bound applications to accelerate 1.5x to 10x with SuperSpeed-NT.

SuperCache and SuperSpeed support both write through mode and lazy write mode. In write through mode, all writes to disk are written synchronously to both memory cache and backing disk. In write through mode if your system experiences a power failure or crash, all your data is 100% safe. However, your system may run slightly slower than it would in lazy write mode.

In the lazy write mode of SuperCache and SuperSpeed data written to the virtual disk goes into a special lazy write buffer. This buffer is in an area of main memory reserved for this purpose. The system is not slowed down waiting for the data to be written to the hard disk drive. The disadvantage is that this main memory is volatile and its contents are lost if the system crashes or power fails before the data has been written to disk. The lazy write mechanism writes bursts of data to disk once a second in the background. The cache is completely flushed to disk automatically at system shutdown time. You may also flush it at any time by executing the ScFlush or SdFlush command from the MSDOS command line.

SuperSpeed Software recommends use of an uninterruptable power supply (UPS) if you use SuperCache or SuperSpeed in lazy write mode. If you have a very large lazy write cache and a slow disk, it may require a considerable amount of time to fully flush the cache. You will want to be sure your UPS is capable of supplying power to your system for as long as it takes to flush the lazy write cache. To determine how long this is, flush the cache by executing the SdFlush or the ScFlush command from the MSDOS prompt after you have operated your system for 10-20 minutes. Measure the time this flush takes with your watch and allow some margin of error.

If you have a laptop computer with power management software, we recommend that you use write through mode, rather than lazy write mode. If you have a power management suspend option with any system, you should not use the lazy write feature.