passing data to the next layer processing may include determining that the request should be passed directly to the next layer for example some requests may require little or no processing by layer 2 so data may be passed through layer 2 with little or no processing the processing of the request may be complete without needing to pass through all the layers for example the request may be finished being processed at layer 3 each layer isolates functions from the layer above it allowing the upper layers to be abstracted from lower layers examples of layered device architectures include windows operating systems such as windows nt windows 2000 and windows 2003 fig2 is a block diagram illustrating one embodiment of a layered device i o architecture that includes a sync driver in this example i o manager 202 manages input and output requests i o manager 202 passes requests directed to disk drive 214 to sync driver 204 sync driver 204 is an example of a file system quiescing driver sync driver 204 can intercept user mode requests targeted at drive 214 to prevent data from being written to the cache user mode requests include requests from applications such as word or excel in some embodiments sync driver 204 is written according to a windows specification for filter drivers file system driver 208 and disk driver 212 are other drivers that may be associated with the driver stack other drivers 206 and 210 may include any appropriate drivers such as a virus.