10+15*10 = 160
1 cyl = 15 tracks = 160* 15= 2400 tracks
1 track = 2 records = 2400* 2 = 4800 records
The max recoreds 4800 . Correct me if i m wrong.
You are wrong.
First, as BillyBoyo indicated, the mainframe only writes BLOCKS of data, so your count is off by a factor of over 300. (27920 / 80)
Second, a data set may take up to 5 extents to allocate the primary space and each extent counts against the 16 limit on a volume, so the secondary allocation could be as small as 11 extents.
Third, if the data set is on multiple volumes, you have to calculate the space for EACH volume. And data sets can be allocated on up to 59 volumes, so your calculation could be off by a factor of 59 in addition to being off by another factor of over 300.