NEC Express5800/320Fc Manual download pdf (Page 146)

System Boot Problems

9-2 Express5800/ftServer: System Administrator’s Guide for the Linux Operating System

Normal Boot Sequence

The active CPU-I/O enclosure (that is, the primary enclosure whose power switch is lit

green) initiates the boot by starting the BIOS. The BIOS on the booting enclosure scans

the list of bootable devices (as configured in the BIOS) looking for a device to boot.

When the search finds the disks, they are analyzed from bottom to top in the boot

enclosure. When a disk with a boot partition is found, it is booted.

The boot sequence is a multi-stage process:

•

The GRUB boot loader is loaded and started.

•

The GRUB boot loader loads the second stage GRUB, which selects the Linux

kernel to boot, loads, and starts it. The boot process uses the raw disk; RAID is not

involved.

NOTE

For the boot sequence to work, a bootable medium must

be found in the active CPU-I/O enclosure. For example, if

you try to boot the top CPU-I/O enclosure, the boot

sequence fails if sda is missing and there is no other

bootable disk. If a boot partition is found in sdb or sdc, it is

booted. If the boot fails, the system switches the active

CPU-I/O enclosure and tries again (where it will find and

boot sdd, if present).

•

When the kernel starts, it loads the SCSI driver, which in turn loads the SAS (SATA) driver.

•

The SAS (SATA) driver spins up all the disks it discovers. It also collects a list of all of the

type 0xfd (Linux RAID autodetect) partitions.

•

When the RAID-1 module is loaded, it processes this list of mirrors and starts RAID

arrays. It processes mirrors from disks in the following order: sda, sdd, sdb, sde,

sdc, and sdf. If a RAID array was not cleanly shut down, a resync is started.

NOTES

1. The RAID arrays that are started are started as

described above, regardless of what kernel was

booted (or which disk contained the kernel).

2. The recommended configuration of sda and sdd

system disks results in the expected boot

sequencing. The kernel is found in sda or sdd, and the

system file systems are also on sda and sdd.

•

Later in the boot sequence, /etc/rc.sysinit runs. It finds and starts any RAID

arrays in /etc/mdadm.conf that were not already started and that are required

by mounts in /etc/fstab.

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NEC Express5800/320Fc Manual Page 146

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