Magic SysRq Key Sequences over Remote DRAC5 Connection
robert at timetraveller.org
Thu Jun 3 21:45:05 CDT 2010
On Wed, 2 Jun 2010, Bryce Nesbitt wrote:
> These servers run Debian Linux, and we periodically have problems with out
> of control memory situations. We could save servers from a hard reboot by
> sending Magic SysReq commands such as "m" and "f" (to dump Linux Kernel
> memory stats and invoke the Out of Memory Killer (oom-killer). Or make a
> reboot nicer by syncing disks first. These commands work fine directly from
> an attached keyboard (e.g. Alt-SysRq-m). Can we get Magic SysRq over DRAC5?
Hi Bryce. Do you mean in a situation in which a shell cannot be opened on
the system? /proc/sysrq-trigger can be used if you can open a shell as
root (say over DRAC). The WP article shows how to use sysrq-trigger.
There are plenty of situations in which a shell can be opened but a
normal reboot has become impossible - I often use sysrq-trigger in these
The page below talks about how to use Magic Sysrq over a serial console.
Email: robert at timetraveller.org Linux counter ID #16440
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