1. The choice of erasure algorithm has a very strong impact on the total processing time. For example, if a three-time overwriting algorithm is chosen, it will take three times longer to compete the erasure than a one-time overwriting algorithm. Based on established studies and research such as the latest NIST 800-88 revision and the storage security ISO 27040, a one-time overwriting algorithm carried out by a third party approved erasure software does sufficiently achieve a non-recoverable status of the data.
- Unless a specific security regulation requires multiple overwrites, Blancco can recommend HMG Infosec Lower Standard one-time overwriting for the logical level.
In case of compressed data, Blancco’s proprietary overwriting method “Aperiodic random overwrite” (designated as #50 in the software) should be used to overwrite with random data.
2. The system being targeted for erasure should be configured so that multiple smaller LUNs exist in place of one large LUN.
- The total storage size should be distributed as evenly as possible amongst these multiple LUNs.
3. When not running Blancco LUN Eraser from the target system’s own operating system, connect as many external servers (each of which has Blancco LUN Eraser installed upon it) as possible. Divide the LUNs as evenly as possible between the different servers (taking into account both the amount and size of the LUNs).
- Windows Server 2008 and later is recommended.
- Equip the servers with the best hardware possible (RAM, processor, etc.)
Points 4 and 5 specifically apply to Blancco LUN Eraser in Windows environments
4. Use the /multishred command in Blancco LUN Eraser to simultaneously erase as many LUNs as possible from each Blancco LUN Eraser server. Twelve LUNs at a time per server is a good goal. More than that may result in a system crash.
- The /multishred command consumes all available system resources instead of allowing the system to allocate resources to other functions which slows down the erasure speed.
5. Use the /buffersize command in Blancco LUN Eraser to change the size of the overwriting buffer. The user can configure the software to choose an optimal buffer size dynamically. Another option is to select the buffer size manually through trial and error by the user. A good recommendation from Blancco is somewhere between 30 and 50 MB. See the user manual for more information.