Block is 512 in DMX2 and below, 520 in DMX3 and above (except some AS400 volumes which have 8 more bytes)  A block is the smallest IO that a FBA host can read/write.
I was going though a old discussion  [URL]#400093  and got this calculation :  Old Symms and DMX1-2:  1 sector = 512 bytes 1 block = 8 sectors = 4 kb 1 track = 8 sectors = 32 kb 1 cyl = 15 tracks = 480 kb  DMX3-4: 1 sector= 512 bytes 1 block= 8 sectors = 4 kb 1 track= 16 sectors = 64 kb 1 cyl = 15 tracks = 960 kb   so, In Symmetrix the basic addressable unit is sector or block ? and is this DMX3-4 calculation applicable for Vmax(10,20,40K) also ?
sector\block\track\cyl relation in symmetrix,dmx,vmx