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Is there a way to perform a sort of "hard reset" on a remote system (running linux)? The issue i'm facing is related to one of the hard drives dying during I/O and becoming inaccessible - after reboot, the hdd simply disappears from the device list. Only when power is completely cut - it will come back alive, that is when the system is shut down and booted normally (via the according power button). This is on a server, so I always have to trip down to the server room to get it resurrected. The end result is to get all data off the drive (which, so far, i am failing to do due to the described problem).

What I want to do is somehow fully cut the power and make the system boot instantly or after a small delay. I have witnessed such functionality while performing some BIOS upgrades. It's like a bootstrap code.. first the OS is shut down (power is cut) and then after like 5 seconds the system starts booting. All input on the whole topic is very welcome (some smalltime/lowcost network ON/OFF switches, WOL, etc).

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also, perhaps there's some way of just cutting down the power to hdds on reboot? –  XXL Oct 21 '11 at 12:25

2 Answers 2

You could build an ITAPPMONROBOT - but the hard disk will die, probably very soon. It is unlikely that you can get much of the data off it. This assumes you already have checked connectors and cables and they are OK.

Oh, and there is dd_rescue - which ignores read errors - but I don't expect wonders in your case.

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To reset your server remotely

echo b > /proc/sysrq-trigger

This is pretty much the same as pressing the reset button. I'd really suggest syncing the disks fist before hand though....

echo s > /proc/sysrq-trigger
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I haven't tried it, but doesn't SysRq b simply trigger a reboot? The OP is asking for a way to programatically cut the power and then turn it back on after a short while. (And it's been a while, so I'd wager a guess that the disk is dead by now.) –  Michael Kjörling Jun 1 '12 at 8:23
    
Okay, so i found this question whilst hunting for a remote hard reset option myself, then found the answer in another tab. so added to this and then only really read the question. Couldn't find a "How do i remotely do a hard reset question", so left it there in case someone might do the same search and find this answer. I also suspect the hard drive is long since dead. But someone may find it useful. –  Decado Jun 4 '12 at 8:49

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