On Thu, 19 Apr 2007 12:28:48 EDT, Bill Fairchild wrote: > .... If the control unit were to ignore synchronous requests and >always destage asynchronously, then I believe it is possible for non-destaged >tracks to be overwritten by another application if the tracks are deallocated, >reallocated to another application, and then written onto before being >destaged. Control units have no knowledge of VTOCs, allocated extents, other MVS >metadata, and when ownership of a track is released by software process Y and >then picked up by process Z.
I don't follow you here Bill. Of course the control unit doesn't know about any logical data structures. It does, however, have to keep track of where all data is located. If there is a copy of a track in cache, it has to know about that and always ensure that the correct copy is updated or returned. The fact that there has been a request to destage the track from cache does not alter that. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
