In this discussion there should be a differentiation between reusing a DA SD allocation while still under your physical control (giving the mdisk to another user), and relinquishing physical control (return to vendor durin g an upgrade or selling it to 3rd-party or turning it over to the federal excess list).
I use one pass of format by DIRMAINT to clean an allocation before allowi ng reuse withing my own installation. But it the DASD has to leave the building, I use ICKDSF or FDR/Erase several times before it gets powered off. And if the data was really sensitive, the platters get removed (fun job on real 3380s), shredded into confetti and then melted. /Tom Kern /301-903-2211 On Thu, 8 Oct 2009 07:28:48 -0600, Scott Rohling <[email protected] > wrote: >Working with a customer running Linux on zSeries under zVM... discussin g >clean up of disk areas when a Linux server is removed. The 'norm' >according to the customer is to use anywhere from 3 to 35 'passes' to er ase >data, depending on sensitivity. I'm wondering if anyone can provide in put >about how this relates to various cleanup available... I'm confused on a >couple of fronts: > >- I'm probably not understanding -- but writing 1's or 0's more than on ce >to a disk area seems, well, silly. Do 'passes' imply that each pass is >covering more 'area' or something? Whenever I do things like 0 a disk >using the dd command -- I assume the entire disk is being written to and any >subsequent dd commands are unnecessary and redundant. > >- If we do a DIRM PURGE user CLEAN -- is that sufficient to meet any Do D >rules, etc concerning securely wiping data? Same for CPFMTXA FORMAT a nd >any other utilities used from zVM to 'clean' DASD... does anyone actua lly >run these more than once? > >I'm sure I'm not understanding the context of 'passes' and just want to be >able to talk intelligently as I can about how their concept of passes >relates to how mainframe DASD is dealt with - especially at the zVM leve l. >This is always where I come to hear several points of view and get usefu l >insight -- so any input would be most welcome! > >Scott > >p.s. Considered posting this in Linux-390 .. but it's really more of a zVM >thing to me - especially since I plan to use DIRMAINT CLEAN functions to >remove Linux servers from zVM. >
