About Background Tasks; About Initialization - 3Ware 9550SXU-16ML User Manual

About Background Tasks

Background tasks are maintenance tasks that help maintain the integrity of
your drives and data. These tasks include
Initialization of new units
Rebuilds when units have become degraded
Unit verification
Migration of an on-line RAID from one RAID configuration to another
Self-tests

About Initialization

Some RAID levels must be initialized for best performance. (For specifics,
see "Initialization of Different RAID Types" on page 170.) Initialization can
take place before the units are put into service (foreground initialization) or
while the units are being used (background initialization).
Initialization makes parity information valid. Foreground initialization does
this by simply writing zeroes to all the drives so that they all have the same
values. Background initialization uses an algorithm to perform initialization
and does not rewrite existing data.
Foreground Versus Background Initialization
A foreground initialization is run from the BIOS using 3BM. It clears all
existing data from the drives. Foreground initialization can take several hours,
depending upon the size of the unit. After foreground initialization completes,
you can start the operating system and units will perform at peak efficiency.
If immediate access to the unit is important, you can stop foreground
initialization by pressing Esc and boot to the operating system. Background
initialization will then start automatically within about 10 minutes.
Background initialization does not write zeroes to the drives or harm your
data, so you can partition, format, and use the unit safely. For the 9000 series,
the unit is fully fault-tolerant while the initialization takes place.
the array degrades before the initialization is complete, the data will
remain intact.
When initializing is done after booting to the operating system, the process of
initializing takes longer than it does if initialization is done by writing zeroes
to the unit in the BIOS. Consequently, it will be a longer period of time until
the performance of the unit is fully optimal.
Although you can use the unit while it is being initialized in the background,
initialization does slow I/O performance until completed. You can adjust how
much initialization will slow performance by setting the rate at which it
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About Background Tasks
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