Reliability; Data Integrity; Cable Noise Interference; Start/Stop Cycles - Hitachi T7K250 - Deskstar - Hard Drive Specifications

7.4 Reliability

7.4.1 Data integrity

No more than one sector is lost at Power loss condition during the write operation when the write cache option is
disabled. If the write cache option is active, the data in write cache will be lost. To prevent the loss of customer
data, it is recommended that the last write access before power off be issued after setting the write cache off.

7.4.2 Cable noise interference

To avoid any degradation of performance throughput or error rate when the interface cable is routed on top or
comes in contact with the HDA assembly, the drive must be grounded electrically to the system frame by four
screws. The common mode noise or voltage level difference between the system frame and power cable ground or
AT interface cable ground should be in the allowable level specified in the power requirement section.

7.4.3 Start/stop cycles

The drive withstands a minimum of 50,000 start/stop cycles in a 40° C environment and a minimum of 10,000
start/stop cycles in extreme temperature or humidity within the operating range. See Table 35: "Temperature and
humidity" on page 53 and Figure 5: "Limits of temperature and humidity" on page 28.

7.4.4 Preventive maintenance

None

7.4.5 Data reliability

Probability of not recovering data is 1 in 10
ECC On The Fly correction
• 1 Symbol : 8 bits
• 4 Interleave
• 12 ECCs are embedded into each interleave
• This implementation always recovers 5 random burst errors and a 153-bit continuous burst error

7.4.6 Required power-off sequence

The required BIOS sequence for removing power from the drive is as follows:
Step 1: Issue one of the following commands.
Standby
Standby immediate
Sleep
Note: Do not use the Flush Cache command for the power off sequence because this command does not
invoke Unload
Step 2: Wait until the Command Complete status is returned. In a typical case 350 ms are required for the com-
mand to finish completion; however, the BIOS time out value needs to be 30 seconds considering error recovery
time. Refer to section13.0 "Time-out values" on page 241.
Step 3: Terminate power to HDD.
14
bits read
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