With RAMAC Virtual Array, the DDSR option of IXFP does almost the same thing as the erase-on-scratch function. The storage administrator uses DDSR to manage disk space more efficiently. DDSR has the side effect of usually erasing released tracks, even if you do not request the ERASE option. DDSR is faster than the erase-on-scratch function on other types of disks. Without erase-on-scratch, however, DDSR is less secure. The erasure might not complete before data set deletion or space release. After a successful erasure, your data remains physically on disk, in a compressed form, but is not accessible by any software.

If you request erase-on-scratch on a RAMAC Virtual Array for which DDSR is active, the system optimizes the erasure so that it happens much faster than on other kinds of disks. The erasure is guaranteed to complete before data set deletion or space release. After a successful erasure, your data is not accessible by any software.