6:57 p.m.
Dear All,
When the systems freezes, is it safe to hold down the power button to
power off the machine? If not, what alternatives do you suggest?
Thanks in advance,
Paul
8:56 a.m.
Max Pyziur <pyz <at> brama.com> writes:
On Tue, 29 Jan 2013, Paul Smith wrote:
> On Tue, Jan 29, 2013 at 4:24 AM, David G. Miller <dave <at>
davenjudy.org>
wrote:
>>> When the systems freezes, is it safe to hold down the
power button to
>>> power off the machine? If not, what alternatives do you suggest?
>>
>> Simple test: if CapsLock and/or NumLock and/or ScrollLock still work
(keyboard
>> light reflects change in state), you have a shot at the
Alt-SysReq-≤key>
stuff.
<SNIP>
> Thanks, David and all other respondents. In case lights works,
how can
> one get a console?
Ok, I'll play.
<SNIP>
If you're running a LAN/home network and you have other machines
on the
network, and provided those machines have some ssh/telnet client software,
and the (blanket-wrapped) frozen machine is running a telnet/ssh daemon
and set to receive requests, you try accessing the (supposedly) frozen
machine by ssh/telnet client.
<SNIP>
CTRL+ALT+F2 through CTRL+ALT+F6 (where F# = Function key #) will bring up an
alternate console. Hold down Control and Alt then pick a function key. Get
back to the GUI with CTRL+ALT+F1 on Fedora or CTRL+ALT+F7 on RHEL and clones.
If the system is busy, you may have to wait a little while for it to respond.
Another choice is CTRL+ALT+Backspace to kill the GUI. If you start in graphical
mode, the GUI will restart. If you start in text mode, you'll get back to your
original login session.
Cheers,
Dave
8:51 a.m.
On 01/29/2013 03:28 AM, Tim wrote:
Allegedly, on or about 28 January 2013, Sam Varshavchik sent:
> 1) The hard drive does an emergency park of the R/W head. That does
> incur some cost, in terms of wear and tear.
Are there any consumer hard drives that still do a controlled park,
rather than just get switched off?
If you look at a drive's SMART attributes, you will probably see separate
"Power Cycle Count" and a lower "Power-Off Retract Count". Or,
perhaps
not -- depending on the drive and, of course, how it's been shut down.
I have one drive that, even when it is already spun down in standby, will
make an audible click and peg the Power-Off Retract Count when power is
turned off. The rest of mine do not.
--
Bob Nichols "NOSPAM" is really part of my email address.
Do NOT delete it.
7:43 a.m.
Tim:
> Are there any consumer hard drives that still do a controlled
park,
> rather than just get switched off?
Sam Varshavchik:
On my laptop with a ~4 year old hard drive, there's quite an
audible
difference between a forcible power-off, with a clunk, and an orderly
shutdown that turns the power off quietly.
Hmm, I'll have to have a listen out for what my laptop does. I can well
imagine laptops having an emergency shutoff, seeing as some of them use
motion detectors to protect drives against bangs.
But my external drives seem to make the same loudish bang when they put
themselves to sleep, compared to losing power. To be honest, I think
external drives need motion detection. All too often people move them
about while they're running. And the ones that sit upright aren't the
most stable of things.
--
[tim@localhost ~]$ uname -rsvp
Linux 3.6.11-5.fc17.x86_64 #1 SMP Tue Jan 8 21:40:51 UTC 2013 x86_64
All mail to my mailbox is automatically deleted, there is no point
trying to privately email me, I will only read messages posted to the
public lists.
4:26 a.m.
On Tue, Jan 29, 2013 at 2:56 PM, David G. Miller <dave(a)davenjudy.org> wrote:
CTRL+ALT+F2 through CTRL+ALT+F6 (where F# = Function key #) will
bring up an
alternate console. Hold down Control and Alt then pick a function key. Get
back to the GUI with CTRL+ALT+F1 on Fedora or CTRL+ALT+F7 on RHEL and clones.
If the system is busy, you may have to wait a little while for it to respond.
Another choice is CTRL+ALT+Backspace to kill the GUI. If you start in graphical
mode, the GUI will restart. If you start in text mode, you'll get back to your
original login session.
Thanks, David, for your clear and detailed explanation.
Paul
7:56 p.m.
Tim writes:
Hmm, I'll have to have a listen out for what my laptop does. I
can well
imagine laptops having an emergency shutoff, seeing as some of them use
motion detectors to protect drives against bangs.
But my external drives seem to make the same loudish bang when they put
themselves to sleep, compared to losing power.
That seems to be rather broken. I can't claim to be a big HD expert, but
having the platters stop spinning with the heads still flying over the
platters will crash the heads, and permanently ruin the drive, so the heads
must return to their parking position before the drive stops spinning.
In an orderly shutdown, the heads get returned to their parking spot, during
ordinary course of business, then the power goes off.
The "clunk" is when the drive detects a loss of power, and it's using its
reserve power, in some capacitor or something, to just yank the heads out of
the way, ASAP, to avoid a head crash. It's got limited power, so it can't
waste milliseconds bleeding it off by moving the heads slooowly to their
parking spot. So, they get yanked off the platter, ASAP. And the clunk is
the heads slamming against the end stop. Which is preferrable to having the
heads crash on the platters.
If your drive knows it wants to go to sleep, it should be moving the heads
normally into the parking location, instead of just cutting off its own
power, and have the heads go into an emergency retract.
7 a.m.
On Tue, 29 Jan 2013, Paul Smith wrote:
On Tue, Jan 29, 2013 at 4:24 AM, David G. Miller
<dave(a)davenjudy.org> wrote:
>> When the systems freezes, is it safe to hold down the power button to
>> power off the machine? If not, what alternatives do you suggest?
>
> Simple test: if CapsLock and/or NumLock and/or ScrollLock still work (keyboard
> light reflects change in state), you have a shot at the Alt-SysReq-<key>
stuff.
> The keyboard lights are actually controlled by the O/S (keyboard driver
> specifically). If the O/S is dead, the lights won't change state when you push
> whatever.
>
> I've had fairly good luck with this test. Lights work --> be patient and see
if
> you can get an alternate console, shell in, etc. Lights don't work --> power
> key time.
Thanks, David and all other respondents. In case lights works, how can
one get a console?
Ok, I'll play.
<humor>
It all depends on how much room you have in the living room; sometimes all
you can fit there is a spinet. But if the space is there, go for a grand.
</humor>
If you're running a LAN/home network and you have other machines on the
network, and provided those machines have some ssh/telnet client software,
and the (blanket-wrapped) frozen machine is running a telnet/ssh daemon
and set to receive requests, you try accessing the (supposedly) frozen
machine by ssh/telnet client.
If can login successfully, then you can try doing some forensics (looking
for log files, and other evidence/detris), and in the end, if necessary,
reboot the box (usually, su to root, type "reboot," and politely tap
<enter>).
Paul
fyi,
Max PYziur
pyz(a)brama.com
5:59 a.m.
Tim writes:
Allegedly, on or about 28 January 2013, Sam Varshavchik sent:
> 1) The hard drive does an emergency park of the R/W head. That does
> incur some cost, in terms of wear and tear.
Are there any consumer hard drives that still do a controlled park,
rather than just get switched off?
On my laptop with a ~4 year old hard drive, there's quite an audible
difference between a forcible power-off, with a clunk, and an orderly
shutdown that turns the power off quietly.
5:15 a.m.
On Tue, Jan 29, 2013 at 4:24 AM, David G. Miller <dave(a)davenjudy.org> wrote:
> When the systems freezes, is it safe to hold down the power
button to
> power off the machine? If not, what alternatives do you suggest?
Simple test: if CapsLock and/or NumLock and/or ScrollLock still work (keyboard
light reflects change in state), you have a shot at the Alt-SysReq-<key> stuff.
The keyboard lights are actually controlled by the O/S (keyboard driver
specifically). If the O/S is dead, the lights won't change state when you push
whatever.
I've had fairly good luck with this test. Lights work --> be patient and see if
you can get an alternate console, shell in, etc. Lights don't work --> power
key time.
Thanks, David and all other respondents. In case lights works, how can
one get a console?
Paul
4:01 a.m.
2013/1/29 Sam Varshavchik <mrsam(a)courier-mta.com>:
When the machine freezes, try pressing Alt-SysRq-b to force a reboot, if the
kernel is still alive, somewhere. This will still require a filesystem
repair, but at least it'll save wear/tear on the hard drives.
Even better is to use Alt + SysRq + REISUB (sequentially)
R = unRaw (take control of keyboard back from X),
E = tErminate (send SIGTERM to all processes, allowing them to
terminate gracefully),
I = kIll (send SIGKILL to all processes, forcing them to
terminate immediately),
S = Sync (flush data to disk),
U = Unmount (remount all filesystems read-only),
B= reBoot.
http://en.wikipedia.org/wiki/Magic_SysRq_key
Greetings,
--
Jorge Martínez López <jorgeml(a)gmail.com> http://www.jorgeml.net
3:28 a.m.
Allegedly, on or about 28 January 2013, Sam Varshavchik sent:
1) The hard drive does an emergency park of the R/W head. That does
incur some cost, in terms of wear and tear.
Are there any consumer hard drives that still do a controlled park,
rather than just get switched off?
--
[tim@localhost ~]$ uname -rsvp
Linux 3.6.11-5.fc17.x86_64 #1 SMP Tue Jan 8 21:40:51 UTC 2013 x86_64
All mail to my mailbox is automatically deleted, there is no point
trying to privately email me, I will only read messages posted to the
public lists.
10:24 p.m.
Paul Smith <phhs80 <at> gmail.com> writes:
When the systems freezes, is it safe to hold down the power button
to
power off the machine? If not, what alternatives do you suggest?
Simple test: if
CapsLock and/or NumLock and/or ScrollLock still work (keyboard
light reflects change in state), you have a shot at the Alt-SysReq-<key> stuff.
The keyboard lights are actually controlled by the O/S (keyboard driver
specifically). If the O/S is dead, the lights won't change state when you push
whatever.
I've had fairly good luck with this test. Lights work --> be patient and see if
you can get an alternate console, shell in, etc. Lights don't work --> power
key time.
Cheers,
Dave
7:38 p.m.
On 01/28/2013 05:31 PM, Sam Varshavchik wrote:
When the machine freezes, try pressing Alt-SysRq-b to force a reboot, if
the kernel is still alive, somewhere. This will still require a
filesystem repair, but at least it'll save wear/tear on the hard drives.
In an ext3/ext4 filesystem, journaling will often correct any errors
without needing to fsck; if not, the system will do it on its own at
boot. And, if the Magic SysRq is working, using Alt-SysRq-s will force
a sync before forcing a boot. I need to do ^Alt-SysRq to get it to work
and then, only if the system hasn't locked up.
7:36 p.m.
On 01/29/2013 12:57 AM, Paul Smith wrote:
Dear All,
When the systems freezes, is it safe to hold down the power button to
power off the machine? If not, what alternatives do you suggest?
looking for more fish? (GBWG)
if your system is freezing, put a heavy blanket around it to keep
it warm.
if the power button is on top of machine, holding it _down_ is ok.
if power button is on the front, holding it _in_ would work better.
your alternatives would be pulling power cord from back of machine
or removing power cord plug from wall.
main thing is, does machine freeze often and what is causing it
to freeze up.
Thanks in advance,
again, you are welcome.
--
peace out.
tc.hago,
g
.
*please reply "plain text" only. "html text" are deleted*
7:31 p.m.
Paul Smith writes:
Dear All,
When the systems freezes, is it safe to hold down the power button to
power off the machine? If not, what alternatives do you suggest?
Thanks in advance,
There are two consequences to a hard poweroff, like that:
1) The hard drive does an emergency park of the R/W head. That does incur
some cost, in terms of wear and tear.
2) The filesystem state is inconsistent. That does not usually result in any
damage. The filesystem should get automatically re-fscked on the next
reboot. Still, after a forced poweroff, it is a good idea to "touch
/forcefsck" and reboot one more time, to force a full fsck on all
filesystems (which will take some time to complete).
As far as recovering, there are basically two things that can be tried,
before giving up and yanking the power.
A) Sometimes only X, or the UI is frozen, but the kernel continues to crawl,
to some extent, underneath. If you were connected to a network, you can try
ssh-ing in, and running 'poweroff'. Of course, this assumes that you had ssh
enabled. If you're able to ssh-in and execute 'poweroff', be patient, it may
take 5-10 minutes for a crippled machine to figure out how to kill off
everything, and reboot.
B) Execute:
echo 'kernel.sysrq = 1' >/lib/sysctl.d/99-sysrq.conf
sysctl --system
When the machine freezes, try pressing Alt-SysRq-b to force a reboot, if the
kernel is still alive, somewhere. This will still require a filesystem
repair, but at least it'll save wear/tear on the hard drives.
7:23 p.m.
On 01/28/2013 04:57 PM, Paul Smith wrote:
Dear All,
When the systems freezes, is it safe to hold down the power button to
power off the machine? If not, what alternatives do you suggest?
My laptop doesn't do that. My desktop does, and most of the time I have
to use the reset button, but if that doesn't work, there's nothing left
except the power button and if so, there's not really much else I can
do. You might try activating the Magic SysRq key
(http://www.linuxhowtos.org/Tips%20and%20Tricks/sysrq.htm) and seeing if
that works, but for me, it only works when it's not frozen.
4162
days inactive
4163
days old
17 comments
10 participants
participants (10)
-
David G. Miller (aka DaveAtFraud) -
g -
Joe Zeff -
Jorge Martínez López -
Max Pyziur -
Paul Allen Newell -
Paul Smith -
Robert Nichols -
Sam Varshavchik -
Tim