Re: Remounting as read-only

[matthew sporleder <msporleder%gmail.com@localhost>]

The few tips I have on http://www.mspo.com/netbsdreadmostly.html are
still valid as far as I know.  I've been using a union mount for
/var/log and /var/run for a while, but I think it is a little funny
and have been considering switching back to seedfs
http://mspo.com/code/mount_seed_tmpfs



On 5/15/10, jgw%freeshell.org@localhost <jgw%freeshell.org@localhost> wrote:
> Stephen Borrill <netbsd%precedence.co.uk@localhost> wrote:
>
>> On Fri, 14 May 2010, Steven Bellovin wrote:
>> >>> That updates it to rw, which is not what you want. There was another
>> >>> person
>> >>> asking for this in NetBSD 5.0. Turns out it can't sync meta data upon
>> >>> remount read only: http://gnats.netbsd.org/30525
>> >>
>> >> I'm not sure what you mean by "it", but I should point out that the bug
>> >> in question -- kernel doesn't sync metadata on read-only remount -- is
>> >> extremely old, and *did* cause disk corruption after r/o remount set
>> >> the filesystem "clean" flag, thus corruption fsck would never find and
>> >> which could potentially eat your disk over time.
>> >>
>> >> It's *always* been broken.  Not just in NetBSD, probably in 4.4BSD
>> >> and prior kernels as well.  It is unquestionably broken at least in
>> >> older
>> >> releases of the other BSDs as well. We have opted for safety over a
>> >> false
>> >> sense of security.
>> >
>> > Yup, understood.  I just want it to work, and work properly; it's a
>> > useful feature for embedded systems:
>> >
>> >    # uptime
>> >    11:21AM up 593 days, 14:32, 0 users, load averages: 0.06, 0.08, 0.08
>> >
>> > With, probably, half a dozen configuration changes during that time.
>>
>> *nod* That's exactly how I use it too (in thousands of machines in
>> production daily with no problems). I suppose it might be argued that you
>> could use WAPBL now.
>
> I'm curious if there are any "best practices" for those wishing to install
> NetBSD in its current form (ie. WAPBL, ptyfs, kernel modules, ??) on
> compact flash (and similar media).  Most of the guides seem to be several
> years old now and, to a non-developer like myself, it's unclear what tweaks
> should be made.  In the case of WAPBL (journaling) I'd think it ought to
> be turned off to prevent excessive disc writes, no?
>
> Regards,
> Jeff
>