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how to boot into failsafe mode

how to boot into failsafe mode

how to boot into failsafe mode

Hi All - I have a T1000 Sun Box and was wondering if you could tell me how to boot into "failsafe" mode?

Also, what is "failsafe" mode?

Thank you for your assistance!!


Sebastian Jazzer
MCSE 4.0 & 2000, Network+, A+, Web Developer

RE: how to boot into failsafe mode

Are you talking about "Single User Mode"?

Rrom the OK:
boot -s

If your all ready running
reboot -- -s

Single user mode means only root can login and from the console/terminal.  Very few processes are running, no network, and nothing but required file systems are mounted.

Often patches require that you are in single user mode during install.

RE: how to boot into failsafe mode


 I didn't mean single user mode. I mean the actual "failsafe" option when booting a solaris 10 x86 machine.

I'm also wondering how it would be done in the SPARC environment as well. (There is no "failsafe" in SPARC, but there is the equivalent of one...)



Sebastian Jazzer
MCSE 4.0 & 2000, Network+, A+, Web Developer

RE: how to boot into failsafe mode

T1000, they are sparc aren't they and not x86?  I know T2000 are sparc.

on x86 machines, you get to failsafe via grub, so when you reboot the system, you have X seconds to pick `fail safe mode`. So that would mean you have your console working. for the x4500,x4600, they use the ilom, I am not sure if all of Sun's x86 line uses ilom though.
What I have used failsafe for is the same as mounting your root disk on your system via a cdrom or on the net. IE: boot cdrom -s, boot net -s.  it will mount just the necessary files needed for you to fix your issues, just as the boot net ... does.

if you are wanting to go into `single-user` mode from run level 3, you can use the `init s` command to bring you to single-user. I have notice that `reboot -- -s` will not work, it still takes you back to run level 3 after the reboot. at least for the x4500 servers, I would assume all x86 will have the same response.

You asked about sparc, and what the equiv is, Sparc uses OBP, which lets you run an assortment of commands from a prompt called the `OK>`.

OK> boot cdrom -s
OK> boot net -s

sparc is much easier, I believe.

you just take the system to the `ok` prompt using init 0 and run boot cdrom -s, or boot net -s, or from Solaris you can use reboot -- "cdrom -s" or reboot -- "net -s".

if you have a jumpstart server you can use the `net -s` option, if not just use a cdrom/dvdrom with the "cdrom -s" option.

once you get to the root prompt after running one of the above commands, you just mount your root drive, so if your root drive is c0t0d0s0, them you would just do the following  to fix an issue like what follows.

if you have a bad entry in the /etc/vfstab in regards to a separate /var on your server and this is why it would not boot, then you would.

mount /dev/dsk/c0t0d0s0 /mnt
then you: cd /mnt/etc
vi vfstab (make your changes)

then reboot

failsafe will let you do the exact same thing.

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