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Posts Tagged ‘Data Destruction’

Secure Erase and checking for random data, erased disk drives

January 3rd, 2009 No comments

Below is from the smartmon-ux manual, and shows examples of commands one can use to see if a disk contains random data, as well as how data was distributed on a disk before and after running the Secure Erase command. Read more…

DoD Secure Erase

January 3rd, 2009 3 comments

Users want and need a simple and secure way to erase all their data from disk drives, when releasing them from their physical control for resale or repair. Over a third of drives resold on eBay contain personal data such as credit and medical records.  These drives come from PCs, servers, ATM machines, banks, and workstations. It is important to initially emphasize that erasure security can only be relative. When handling data classified at secret and higher, the edict is that ‘data must be destroyed using methods that assure that legacy information cannot be recovered by any means’. Government document DoD 522.22M is commonly quoted on erasure methods, and requires physical destruction of the storage medium (the magnetic disks) for data classified higher than Secret. [Ryk: subjective in most cases to the sensitivities of the Cognizant Security Authority responsible for the storage asset of data.]

However, even such physical destruction is not absolute if any remaining disk pieces are larger than a single 512-byte record block in size, about 1/125” [Ryk: this size is currently 1/250 of an inch due to the chemistry of current high capacity storage media] today’s drives. Pieces of this size are found in bags of destroyed disk pieces studied at CMRR. Magnetic microscopy can image the stored recorded media bits, using the CMRR scanning magnetoresistive microscope. Physical destruction nevertheless offers the highest level of erasure because recovering any actual user data from a magnetic image requires overcoming almost a dozen independent recording technology hurdles. This is an example of “exotic time consuming technology” necessary as the barrier to data recovery for the highest level of erasure security. Even if these hurdles were overcome, about an hour would be required to recover one single user data block out of millions on the disk. Recovering substantial amounts of data in less than months requires that the disk be intact and undamaged so that heads can be flown over it to obtain data playback signals, and also overcoming the technology hurdles. Simply bending a disk makes this impossible.

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SCSI Format Unit Command options

January 2nd, 2009 No comments

 The SCSI FORMAT UNIT command is used to format a SCSI, FC, SAS, or any disk that utilizes the SCSI command set into logical blocks.   One would send this command (or run an application that sends this command) to to zero all of the data on the disk (if the command is used correctly).   If you just changed the block size of the disk from 512, to 520/528 or vise-versa, then you must also make sure the disk is reformatted before you can use it.  

In order to have the desired effect, you must make sure that whatever format utility you use sets the parameters you desire.  The various built-ins that come with IRIX, Solaris, etc, don’t provide a mechanism that lets you control all of the settings you may need. Furthermore, the default values may or may not be reasonable.  

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General thoughts on data security, destruction, protection

January 2nd, 2009 No comments

There are several ways to destroy the data on disk drives.  This entry covers the basics of them and exposes their relative risks. Read more…