Chapter 1. Introducing the 3ware® SATA RAID Controller
14
3ware Serial ATA RAID Controller User Guide
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Staggered Spinup
allows drives that support this feature to be powered-
up into the standby power management state to minimize in-rush current
at power-up and to allow the controller to sequence the spin-up of drives.
Both SATAII OOB and ATA spin-up methods are supported. The standby
power management state is persistent after power-down and power-up.
You can set the number of drives that will spin up at the same time, and
the time between staggers in 3BM (the 3ware BIOS Management utility).
For details, see “Enabling and Setting Up Staggered Spin-up” on page 94.
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Verification and Media Scans.
The verify task verifies all redundant
units, and checks for media errors on single disks, spares, JBODS and
RAID 0 unit members. If the disk drive is part of a redundant unit, error
locations that are found and are deemed repairable are rewritten with the
redundant data. This forces the drive firmware to reallocate the error
sectors accordingly. (For more information, see “About Verification” on
page 151.)
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Error Correction
. Bad sectors can be dynamically repaired through error
correction (Dynamic Sector Repair). Reallocation of blocks is based
intelligently on the location of the block in relation to the stripe.
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Scheduled Background Tasks.
Initialize, rebuild, verify, and self-test
tasks can all be run in the background, at scheduled times. This lets you
choose a time for these tasks to be run when it will be least disruptive to
your system. You can also define the rate at which background tasks are
performed, specifying whether I/O tasks should be given more processing
time, or background rebuild and verify tasks should be given more
processing time. (For more information, see “Scheduling Background
Tasks” on page 161.)
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Write Cache
. Write cache can be enabled or disabled using 3BM 2,
3DM 2 and CLI. When write cache is enabled, data will be stored in
system cache, 3ware controller cache, and drive cache before the data is
committed to disk. This allows the system to process multiple write
commands at the same time, thus improving performance. However when
data is stored in cache, it could be lost if a power failure occurred. With a
Battery Backup Unit (BBU) installed, the cache stored on the 3ware
controller can be restored. (For more information, see “Enabling and
Disabling the Unit Write Cache” on page 113.)
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StorSave Profiles
allow you to set the level of protection versus
performance that is desired for a unit when write cache is enabled. (For
more information, see “Setting the StorSave Profile for a Unit” on
page 117.)
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Drive and Unit Identification.
Units or drives in enclosures can be
identified by flashing the applicable LEDs.
When the I
2
C port on the controller has been connected to a chassis with a
Chassis Control Unit (CCU), you can issue drive locate commands that
