Date: Fri, 22 Sep 2006 14:15:31 +0300 (EEST) From: Dmitry Pryanishnikov <dmitry@atlantis.dp.ua> To: dandee@volny.cz Cc: freebsd-stable@freebsd.org Subject: Re: watchdogd_flags followed by panic watchdog timeout, after reboot my rc.conf disappear Message-ID: <20060922133503.F33173@atlantis.atlantis.dp.ua> In-Reply-To: <00f701c6ce1a$9d9ea810$6508280a@tocnet28.jspoj.czf> References: <00f701c6ce1a$9d9ea810$6508280a@tocnet28.jspoj.czf>
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Hello!
On Sat, 2 Sep 2006, Daniel Dvo??k wrote:
> I saved my rc.conf without any doubt.
I believe you, really ;)
> Answear: Because rc.conf had 0 Bytes !!!
>
> -rw-r--r-- 1 root wheel 6174 Sep 1 XX:XX rc.conf , I do not remember
> time of last modification of file.
>
> So the content of rc.conf was completly gone !!!
Yes, because by default "/" is mounted in the following fashion:
noasync
Metadata I/O should be done synchronously, while data I/O
should be done asynchronously. This is the default.
-----------------------------------------------------^^^^^^^^^^^^^^^^^^^^
So yes, /etc/rc.conf will become empty if you're just edited it, and then,
e.g., power disappears. It's a dangerous situation, because box becomes
unreachable via network. To guard against it, you can just mount "/"
using synchronous mode:
sync All I/O to the file system should be done synchronously.
I've just modified my test machine's configuration in this way:
/dev/ad0s3a / ufs rw,sync 1 1
and done several times "edit /etc/rc.conf" -> "power off/on" sequence
(no RESET key on box). The rc.conf is intact (while w/o "sync" it became empty
after my second attempt). Note that this will further decrease FS performance
for "/" (I always follow old good RELENG_4 advise NOT to turn softupdates on
for "/" also). That's why /tmp and /var are separate partiotions (or just
symlinks to SU-enabled /usr) in my typical setup.
> And please explain me somebody, how I lost the content of rc.conf file. :-O
I hope I've just managed to do that ;)
> P.S.: I am not currently subscribed in the freebsd-stable mailling list, so
> use my e-mail address. I am ok with freebsd-current mailling list.
I think my recipe would be more useful in -stable list (which IMHO is
"a must" for reading by the production machines admins), that's why I'm
sending to the -stable also.
Sincerely, Dmitry
--
Atlantis ISP, System Administrator
e-mail: dmitry@atlantis.dp.ua
nic-hdl: LYNX-RIPE
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