Hi my name is Michael and i have specific question about HDD read/write sequence.
Is there any way to uderstand in program way when the data requsted from HDD is taken
from the physical surface or from somewhere else(cahe,buffer,or...)?
Posted on 2004-07-16 19:28:28 by LeXTeRiTY_X
Hi Michael,

actually your question is not so simple at al. I don't know if it is possible to find out that the sector requested is from cache (of the HDD) or from physical disk. I think it is handled internally by the hard disk. The cache used by the Operating System in the computer side is another question, maybe this can be know, that the sector is memory (cached by the system) or not. But I don't know how. Maybe you should look in DDK for IDE controller driver, they handle also the read/write caching of sectors.

Take a look on this forum, maybe you can find some info:
Good source for HDD info?
Posted on 2004-07-17 00:53:55 by bszente
I'll look at your suggestions by the way do you think that os(dos/win98-io.sys)may modify that cache(the hdd) and the when int 13h request sector data the data actually will not be taken from the physical surface but from the cache a.g. io.sys makes the data in cache looks in the way it wants???
thanks once again
Posted on 2004-07-17 15:12:04 by LeXTeRiTY_X
Operating system caching happens ontop of the harddrive caching. I doubt there's any way you can control how the harddrive cashes things - you can query the cache size though. But caching, just like how a sector is converted to cylinder,head,sector (etc) is pretty internal to the drive - *as far as I know*.
Posted on 2004-07-17 15:22:15 by f0dder