Subject: Re: finally i've installed NetBSD-1.5
To: Wojciech Puchar <firstname.lastname@example.org>
From: Manuel Bouyer <email@example.com>
Date: 01/21/2001 14:13:12
On Sun, Jan 21, 2001 at 09:54:22AM +0100, Wojciech Puchar wrote:
> and have some questions and comments. i'm 5-year linux user.
> at first - NetBSD instalation is very EASY - i mean easy not
> "click-easy" like commercial linux distr.. where you think it's easy but
> in fact don't understand anything of it.
> i used sysinst only for creating partitions, then newfs and untarred
> manually. the hardest think was....vi
> my questions (please delete points you don't want to ansfer for)
> 1) there is no /etc/inittab in netbsd. i found /etc/ttys making partially
> it's function to respawn processes but how to respawn processes not for
> console? is /etc/ttys right place to put pppd nodetach on serial line (i
> have leased line with 33600 modem, chatscript and pppd config already
> works in linux, and i found netbsd pppd almost identical to linux)
Yes, I think you can put it there, but I never tried. I have installed
mgetty and have it start pppd when needed (mgetty in started via /etc/ttys).
Anoter option would be to start pppd from the startup script (in think
setting ppp_peers in /etc/rc.conf to a valid /etc/ppp/peers/foo file
is enouth), with 'nodetach' changed to 'persist'. Then pppd will go in
background and restart the connection when it's terminated.
> 2) why it is so fast :)?
> especially - disk transfer from UDMA/66 disk (dd if=/dev/wd1d of=/dev/null
> bs=64k count=5000 give me 26MB/s, and 23MB/s while doing 2 cp processes
> on first disk)
> i have (now) STANDARD generic kernel, while in linux i have -mpentiumpro
> compiled kernel with latest ide-patches etc.. and i'm getting 21MB/s on
> unloaded system maximum.
Don't know, I didn't look closely at the linux driver :)
> 3) why there is no write stalls :) ?
> it is very uncomfortable in linux when copying large files. netbsd is
> quite responsible even of heavy disk load including writes.
The NetBSD VM is better than linux's under load (on the other hand, it's a bit
slower when you have plenty of RAM - need to chose :). Also, linux has
a dynamically sized buffer cache which allows to flush pages to RAM to
use them as buffer cache when there's a lot of filesystem activity.
So under linux pages of the program you're using can be flushed to swap to
be remplaced by buffer caches.
> 4) i've got my netbsd binaries broken (downloaded by friend who didn't
> check sums). not i'm downloading sources and want to recompile NetBSD.
> is it possible to easy recompile it all with -mpentiumpro -O2
> (excluding pkgsrc for now) and make resulting gcc defaults to -mpentiumpro
> (as i have in linux)
Yes, I think you can set 'DBG= -mpentiumpro -O2' in /etc/mk.conf. You may
also need 'HOST_CFLAGS= -mpentiumpro -O2'.
> 5) for what is all this strange option for ffs like cylinder size, groups
> etc. etc. etc.
> for at least 10 years there's no drive with real geometry. how to turn off
> this "optimization" in ffs or it does not matter?
Who told you we don't use 10 years disks ? :) But I don't think it does
matter much. I usually change cpg/sgs from 16 to 256 in the disklabel
(don't know if there's a way to change this from sysinst) to have
larger cylinder groups but that's all.
> why there is so many seeks when cp large files making maximum 3MB/s
> copying speed. can it somewhere be set to delay writes little more to get
> longer writes?
Linux uses async mounts by default (anything is cached and written later).
By default NetBSD uses aysnc for data and sync for metadata. This ensures that
the filesystem on disk is always in a coherent state (you can hit 'reset' even
under heavy write, your system will always reboot without troubles).
NetBSD can also mount filesystems async, but this is not recommended because
you can trash your filesystem in case of unclean shutdown at the wrong time.
But you can use soft updates (mount the filesystem with option 'softdep',
change 'rw' to 'rw,softdep' in the fstab): writes are delayed but are still
ordered, which keep things on disk in a coherent state. Aysnc performances,
but with reliability :)
> read performance is excellent even with many concurrent processes
> 6) how good (stable) is lfs. i found lfs being much faster than lfs
> (with 1048576 stripesize) both reading and writing. will it as good
> with about 80-90% filled disk (so cleanerd would be activated some time)
> can lfs be used on root partition
I would't use the LFS in 1.5 for anything serious. In -current it's a bit
better but it's still experimental. FFS with soft updates should give you
'good enouth' performances :)
> 7) is anything bad in such partition config:
> a: most space
> b: needed swap space
> h: /boot space where kernel will be placed (max 10MB)
> as i had in linux?
On NetBSD, kernel and boot loader are in '/', not 'boot'.
In /bin and /sbin you've some statically linked binaries that can help a lot
in case of disaster.
What I would do is a 50-100MB partition for /, and a separate partition
for /usr with most space (then you can have /usr/home).
Manuel Bouyer <firstname.lastname@example.org>