> ... > No "cache" will ever compete with a RAM disk. RAM is always faster > than disks with their seek/rotational latencies and their much > slower transfer rates.
I knew this would provoke a comment from you, Jack. The purpose of a cache is to put as much data in RAM as it can, so that the disk is accessed as little as possible. It's true that the cached data does eventually get written to disk, and that part is slow. From a speed perspective, though, a well-designed cache can be competitive with a RAM disk. The advantage of a write-delay cache is that that the writing can be done when the system is "idle" (a simple form of multi-tasking). The end result is that even though disk writes actually take the same amount of time they always did, the SYSTEM actually runs much faster. In my experience and opinion (and it is only an opinion), write-through caches don't provide enough speed benefit to be very helpful, and I don't use them. > ... > There is a REASON why "Write Back" caches are all so large -- they > demand MANY "hooks" of a non-generic type into a DOS system, to > handle Ctrl/Alt/DEL and other events that require a "flush" of > sectors not-yet written to disk. Yes, write-delay caches are MUCH more complicated than write-through caches. But, they also provide MUCH more practical benefit, IMO. Even with that being said, I don't use SMARTDRV all the time. I only use it in certain situations when it provides noticeable benefit, and in those particular situations a write-through cache doesn't help. Also, FWIW, you can disable write-delay caching in SMARTDRV if you want, in which case it works sort of like UIDE or LBACACHE (except that it will also _natively_ work with non-INT 13h disks like USB and SCSI), but at the expense of requiring more memory. ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
