> -----Original Message----- > From: Richard Troth [mailto:[EMAIL PROTECTED] > Sent: Wednesday, February 18, 2004 11:48 AM > To: [EMAIL PROTECTED] > Subject: Re: dasdfmt with a 1K block size - still not recommde d? > > > > Why would it not fill the track? >
<snip> > Real 3390 DASD are the same in this aspect. The magnetic markers > between blocks (records) are the same size regardless of the size > of the blocks themselves. Smaller blocks, same inter-block gaps. > Dunno why it would be strictly true for contemporary "3390" which are > emulated by 512-byte FBA critters under the covers, > except perhaps to be true to the emulation. > > -- R; >From what I understand, there are not any "real" IBGs on the emulated DASD. However, MVS and its successors "know" how 3390 track geometry is supposed to work. So the emulated DASD controller must emulate the "overhead" so that "too much" data does not go onto an emulated track. Things like TRKCALC and other access methods depend on an emulated track only getting "x" blocks on a single track when the blocksize is "n". If it got "x+?" where ?!=0, the access method would likely malfunction. Perhaps missing records when doing addressed (to a specific cylinder, head, record) when it tried to calculate this address from a "relative block" number. -- John McKown Senior Systems Programmer UICI Insurance Center Applications & Solutions Team This message (including any attachments) contains confidential information intended for a specific individual and purpose, and its' content is protected by law. If you are not the intended recipient, you should delete this message and are hereby notified that any disclosure, copying, or distribution of this transmission, or taking any action based on it, is strictly prohibited.
