Disk Drive Spin Up Sequence - Acer Altos S700 Series User Manual

58 Chapter 4 RAID Configurations

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)
A typical Mode Page Setting is 12, so if the Remainder = 7, the
EXAMPLE:
Spin Up Delay would be 7 x 12, or 84 seconds.