I am learning Linux. I have a bunch of Linux books, and four books on
Unix. I've read most of most of them, a few cover to cover, to get the
gist of what I'm getting into. I've asked about the subject line in
several Linux newsgroups and not gotten definitive answers. One of my Unix
books (Unix Secrets, 2nd Ed., by James C. Armstrong, an IDG book,
1999) has a little and inadequat chapter (chapter 51, all of seven pages
long) on crashes and its broken down into hardware crashes and software
crashes.
Here is why I'm interested: I've played with Linux now, off and on, for
over 1-1/2 years, and many distribution installs (some crashed on install,
others always install without problems). I've read lots of posts on the
Linux newsgroups. The books say (if and when they talk about it) that
Linux needs a graceful shutdown. You don't just hit the reset button
(which triggers a warm boot) like in DOS or Windows. It also needs a
graceful startup, too.
In the course of my learning (and stumbling over doing stupid things),
I've gotting into things (applications, utilities, whatever) that I did
not know how to get out of and nothing I did would help. Ergo, I had no
option but to shut off the switch. Big surprize on next bootup. It crashes
somewhere before the bootup is completed. I've also had one shutdown that
stopped at some stage before it reached shutdown (this was, I think,
because I used the User Mount Tool in Red Hat version 5.2 of Linux on a
CDROM disk that gave an error message "too many filesystems" and I did not
check for a problem before shutdown. incidentally, with RH ver 6.2 on a
different box, this did not happen when I used the file manager on the
same CDROM disk!). However, I am really not sure. The simplest solution
for these crashes was to re-install my OS (taking about 20-30 minutes).
I have run into three people on another non-comp newsgroup running Linux
who claim that they don't worry about graceful OS shutdowns and turn on
and off their power switches whenever they feel like it (or at least
this is what it sounds like they are saying). One says they have their box
running off the AC power line without a UPS between the power line and the
box. When I ask to tell me how this is possible, I don't get a lot of
detail about how they do it OR why I'm seeing my OS get trashed whenever I
have a lockup (I have since learned a few things about processes that
mis-behave and that I can kill them without an OS shutdown and that
in those cases where the process can't be killed, then a graceful shutdown
will "flush" the problem out [at least so far it has]) and have to do a
power switch off.
Linux install packages have an option for a rescue disk and a protocol for
booting up to get access to the filesystem but then they don't tell you
much (like, zero) about how to diagnose bootup problems (or shutdown
problems). But, I've had boot failures and one shutdown failure and I know
whenever I get it, I'm in trouble and have to reinstall the OS.
At some point in the future I'm going to have to learn how to do
rescues. But, I need to learn more about recovery from crashes AND what
are these three guys doing who are saying they can just turn off their
switches any time they want and turn them back on again [but can't tell
me in detail why they can do it and I can't]?
Is anyone aware of resources on this topic on one or more websites
anywhere?
Art Sowers