Memtech AT3515 Betriebsanweisung PDF herunterladen (Seite 10)

3.5” Bulldog User Guide April 10, 2006 page 10 of 13

4.2 MTBF

The MTBF can be logically calculated in hours using the following formula.

# Flash Chips * # Blocks *Re-programming Cycles * Area Rate

MTBF = ------------------------------------------------------------------------------------

Average Programming Sectors per hour (1 sector = 512 bytes)

Note: The program area is the area that is not changed once it has been programmed.

The remainder of the drive is thus considered “Reprogrammable”. In the case

where 32 Kbytes (64 sectors) are written every 5 minutes into an area occupying

30% of a 512 MB disk (1 Gbit x 4 chips), the MTBF is calculated as shown below:

MTBF = (4*8192*250,000*0.3)/(64*12)

= 3.2 million hours (350 years)

4.3 POWER

4.3.1 POWER DOWN

The AT3515 is shipped with Memtech’s proprietary Kicker™ hold-up circuit. The

Kicker™ provides enough residual power for the drive to complete a write sequence,

thus avoiding data corruption.

Still, it is recommended that power not be removed from any mass storage device while

a write sequence is in progress. This is especially true when disk-caching programs are

being used. Though the Kicker™ protects against data corruption and media errors, it

cannot prevent OS or file errors from occurring. These types of errors arise when the

OS breaks a large transfer into many smaller ones, and only part of the transfer arrives

from the host.

4.3.2 POWER SUPPLY

The AT3515 voltage requirement is specified at +5 volts, +/- 5%. Operation outside of

these limits is not guaranteed. Note that the drive will “operate” below this voltage, but

reliability issues such as uncorrectable errors or invalid data reads may occur. An on

board voltage monitor will inhibit writes when the on-board supply voltage falls below 3

volts, thus preserving data integrity on the drive.

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Memtech AT3515 Betriebsanweisung Seite 10