Definition - What does Staggered Spin-Up mean?
Staggered spin-up is a physical performance strategy for serial ATA hard disk drives or RAID DISK drive systems. With staggered spin-up, engineers handle the electrical load and system capacity during startup by staggering the times when disk drives begin input/output (I/O) operations.
With the traditional strategy, all drives spin up when device or system power is turned on, but staggered spin-up delays the spin up of some drives to provide a more stable demand to the power supply.
Techopedia explains Staggered Spin-Up
Staggered spin-up issues include the following:
Developing system firmware that recognizes the staggered spin-up strategy, rather than demanding that hard disk drives spin up prior to user commands
Operating system (OS) compatibility with the staggered spin-up strategy, preventing situations where an unaware OS reads delayed devices as inaccessible or otherwise does not understand the process.
Staggered spin-up is typically accommodated by a power-on self-test (POST) method, where the basic input/output system (BIOS) controls the boot process.
For LSI Host Bus Adapter (HBA) firmware, what is the difference between IT mode and IR mode?
The two firmware types are Initiator Target (IT) and Integrated RAID (IR). IR is the typical hardware RAID firmware that the internal cards or boards ship with.
The IT firmware, on the other hand, is the Initiator Target firmware which is designed to allow a SAS HBA to connect to up to 256 devices using SAS Expanders. The IT firmware is typically shipped on external cards. The IT firmware does not have any RAID capabilities and simply acts as an HBA.
Basicly the IT firmware is only just a HBA and the boot up time is quick. The IR firmware is the raid software firmware so boot up is a bit longer than having the IT firmware only. You can cross flash with the LSI firmware in IT mode only or IT and IR mode which is default in LSI. If you are going with pure software raid then the IT firmware is best.
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