[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [sheflug] Power cut problem
On 26-Feb-06 David Willington wrote:
> Dear All
>
> I had a power cut the other day. A test server that I think
> was on at the time stopped booting when the power came back on.
> I could mount both hard drives if I booted from Knoppix and
> the file systems seemed undamaged. I got things sorted out
> by running grub-install and it now seems to be fine (after a
> few minutes playing with it). I think what happened was that
> the master boot record was damaged, but can anyone explain
> if the damage is likely to have gone further and if not, why
> not? Is the MBR special in this respect?
>
> The machine is 2Ghz intel processor with 1Gb Ram, 2 IDE hdds (40Gb hda
> mounted at / and 80Gb mounted at /home) with FC4 running various
> services (Apache, mysql, ssh, ftp etc) but no GUI.
>
> I've now got a surge protector.
Good move! Indeed, living in a place where brief power cuts
(a second or three) are not infrequent, I've also installed
a UPS as well, which itself acts as a surge suppressor; but
I have a surge protector between it and the mains as well.
I had a laptop (fortunately a cheapo 2nd-hand) burn out once when
the power flashed off and on about 4 times in quick succession.
I'm not sure what happens mains-wise on these oocasions, and
suspect it is rather variable, but the laptop experience shows
that at least sometimes you can get a true surge sufficient to
cause major damage.
Since in your case things now seem to be running OK again, it
is unlikely that your hardware has suffered. Possibly what
happened is that a mild pulse caused little spikes on the
data lines so that some spurious "data" got written to the MBR
(but could have got written to somewhere else).
Impossible to guess whether or not it's only the MBR. Also do
not exclude the possibility of something having happened (but
not fatally) to the HD circuitry, perhaps causing it to be
unreliable in certain circumstances. You'll just have to suck
it and see. The longer it goes on without problems, the more
sure you can be that nothing serious happened.
But it could be worth carefully watching the screen scroll by
during boot, and also force an fsck and watch that: if there
are significant errors these will mostly be detected either
during the hardware detection phase and mounting the HD, or
during the fsck.
Good luck!
Ted.
--------------------------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding [at] nessie.mcc.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 26-Feb-06 Time: 20:59:18
------------------------------ XFMail ------------------------------
___________________________________________________________________
Sheffield Linux User's Group -
http://www.sheflug.co.uk/mailfaq.html
GNU the choice of a complete generation.