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Disk Drive Spin Up Sequence
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Disk Drive Spin Up Sequence
At power on, the LS module will perform its internal start up
initialization routine. Then the LS module will assert the
disk drive START_1 and START_2 motor start signals low
for disk drive slots 7 through 13, which will spin up the first
7 disk drives immediately. The LS module will then assert
the disk drive START_2 motor start signal low and leave the
START_1 motor start signal high for disk drive slots 0
through 6 which will command the second seven disk drives
to spin up after a delay of 12 seconds times the modulo 8
value of the numeric SEL_ID of the disk drive.
Once the enclosure is powered up and all 14 drives are spun
up as depicted above, the enclosure will support immediate
drive spin up with two power supplies present.
Modulo 8
The drive spin up sequence above uses modulo 8 to calculate
the spin up delay. Modulo 8 is determined by:
(SHELF ID x DRIVE NUMBER)/8 = NUMBER + REMAINDER
It is the REMAINDER value that is used for the calculation
as it is always between 0 and 7 (hence modulo 8). The drive
spin up time can then be calculated as follows:
REMAINDER x MODE PAGE SETTING = SPIN UP DELAY (Seconds)
EXAMPLE: A typical Mode Page Setting is 12, so if the
Remainder = 7, the Spin Up Delay would be 7 x 12, or 84
seconds.