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Power fail and crash recovery

Normally, the system will reboot itself at power-up or after crashes. Provided the auto-restart is enabled on the machine's front panel, an automatic consistency check of the file systems will be performed, and unless this fails, the system will resume multi-user operations.

Cold starts

The system boot procedure loads a boot parameter block from block 0 of the disk configured as the boot device. The boot program finds the corresponding file on the given device (bsd by default), loads that file into memory location zero, and starts the program at the entry address specified in the program header (after clearing off the high bit of the specified entry address).

The file specifications used with “BOOT ANY” or “B/3” are of the form:

where device is the type of the device to be searched, adaptor is the number of the adaptor to which the device is attached, controller is the unit number of the controller or tape formatter on that adaptor, unit is the unit number of the disk or transport slave unit of the tape, and minor is the disk partition or tape file number. Leading adaptor or controller numbers default to 0. Normal line editing characters can be used when typing the file specification. The following list of supported devices may vary from installation to installation:

hd	MFM disk connected to the MFM controller on some VAXstation systems
mt	tape drive connected to an MSCP-compatible controller
ra	disk drive connected to an MSCP-compatible controller
sd	SCSI disk
st	SCSI tape

For example, to boot from a file system in partition ‘a’ of unit 0 of a SCSI disk, type “sd(0,0)bsd” at the boot prompt; “sd(2,0,1,0)bsd” would specify drive 1 on the second SCSI controller. For tapes, the minor device number gives a file offset; “mt(1,2,3,4)” would specify the fifth file on slave 3 of the formatter at “drive” 2 on mba 1.