The time required to purge a SSD depends on the actual purge mode invoked by the
user and the flash memory type / flash memory configuration of the drive. A list of typical
purge times of SSD is listed in Table 1.
7.1 Operating Principle
Clear
Clearing is the processing of erasing data on the media. In a NAND flash based SSD,
this is done by executing a block-by-block erase with verify. Data Purge implements the
block-by-block erase on entire physical flash blocks including user data area and reserved
area for FW, spare and logical to physical mapping table. This results in all the data on
media were erased and unrecoverable.
As soon as the Purge was triggered, SSD will cut off the signals transfer between
Host system and SSD, stop receiving new ATA commands, and force to interrupt on-going
ATA commands; and then SSD will execute block-by-block erase until all blocks in user
data area were erased.
After user data area erased, if “sanitization”mode were invoked, SSD will follow
the sanitization procedure to overwrite/fill the user data area by pre-defined pattern; if
“Clear”mode were invoked, SSD will continue to execute erase on all vendor reserved
data area, logical to physical mapping table, and firmware area. The SSD will be set back
to “blank”with no function after “clear”.
Sanitization
Sanitizing is the process of declassifying the drive by executing an unrecoverable
removal of fall data on the media. In a NAND Flash based SSD, this initiates a sequence
of block-by-block erase, pattern write and pattern verify operations designed to eliminate
any trace of the original data.
KSSDP-VA provides customer standard sanitization procedure by overwriting “1”to
all user data area after block-by-block erase. The SSD will be set back to factory default
with full functions after “Sanitization”.
7.2 User Interface and Operating Guide
Trigger Method
The Data Purge can be triggered by various methods software trigger, hardware
trigger or method combined software and hardware. A successful software trigger would
depend on a functional platform which might be limited by hardware, OS, and application
software used in Host system, and it is hard to guarantee the normal function of host
system in emergency;
Kontron designs a system-independence in-drive hardware mechanism to deliver a
simple and reliable trigger method for Data Purge function.
User Interface and Definition
SSD Clear Speed Clear Time Sanitization Speed Sanitization Time
32G MLC 5GB/sec 6 Secs 60MB/s 8 Mins
64G MLC 10GB/sec 6 Secs 100MB/s 10 Mins
32G SLC 6GB/sec 5 Secs 120MB/s 4 Mins
64G SLC 6GB/sec 10 Secs 120MB/s 8 Mins
