Stop data loss even on system crash? Remember BUSIER

[Ryan Rix]

On Mon 29 June 2009 9:16:52 am Richard Daggett wrote:
> Howdy
>
>  YOu would need to check your kernel settings to see if this is enabled.
>
>  cat /proc/sys/kernel/sysr1 - RHEL 5 it is not enabled by default
>
> Here are more items you can do with it:
>
> <Alt><SysRq>
> (Non-essential.) This is a group of key combinations implemented at the
> Linux kernel level (a low level). It means, chances are these key
> combinations will work most of the time. The combinations are meant for
> debugging purposes and in an emergency (mostly developers); you should try
> other, safer solutions first. The key <SysRq> is also knows on PC as
> <PrintScreen>. The combinations can be enabled/disabled by setting the
> relevant kernel variable to "1" or "0", e.g. : echo "1" >
> /proc/sys/kernel/sysrq <Alt><SysRq><k> Kill all processes (including X)
> which are running on the currently active virtual console. This key
> combination is know as "secure access key" (SAK). <Alt><SysRq><e> Send the
> TERM signal to all running processes except init, asking them to exit.
> <Alt><SysRq><i> Send the KILL signal to all running processes except init.
> This may be more successful in killing runaway processes than the previous
> key combination, but it may cause some of them to exit abnormally.
> <Alt><SysRq><l> Send the KILL signal to all processes, including init. The
> system will not be functional. <Alt><SysRq><s> Run an emergency sync (cache
> write) on all mounted filesystems. This can prevent data loss.
> <Alt><SysRq><u> Remount all mounted filesystems as read-only. This has the
> same effect as the sync combination above, but with one important benefit:
> if the operation is successful, fsck won't have to check all filesystems
> after a computer hardware reset. <Alt><SysRq><r> Turn off keyboard raw
> mode. This can be useful when your X session hangs. After issueing this
> command you may be able to use <Ctrl><Alt><Del>. <Alt><SysRq><b> Reboot
> immediately without syncing or unmounting your disks. Your will likely end
> up with filesystem errors. <Alt><SysRq><o> Shut the system off (if
> configured and supported). <Alt><SysRq><p> Dump the current registers and
> flags to your console. <Alt><SysRq><t> Dump a list of current tasks and
> their information to your console. <Alt><SysRq><m> Dump memory info to your
> console.
> <Alt>SysRq><digit> The digit is '0' to '9'. Set the console log level,
> controlling which kernel messages will be printed to your console. For
> example, '0' will cause only emergency messages like PANICs or OOPSes
> displayed on your console. <Alt><SysRq><h> Display help. Also, any other
> unsupported <Alt><SysRq><key> combination will display the same help.
>
> Richard

Good to now, Richard! Thanks!