Re: lame performance question

[Nick Holland <nick@holland-consulting.net>]

Bob Dog wrote:
> 
> On this same note:
> I plan to set up an OBSD IPF Firewall. However, the
> machine I plan on useing is a Pentium 100 with only
> 8 Megs of RAM. Will this work? Do I need more RAM than
> this? I hope not.
> Thanks in advance.
> Bob Dog
> 
> Sorry for posting twice. But I also planned on useing
> ISA Network cards as this machine only has one PCI
> slot (this is a really old machine). Any known issues
> with PCI Lan cards with OBSD?

You probably don't NEED more RAM, but you will sure wish you had more.
8)
16M for a firewall seems to be a great combination of not swapping in
normal use, and not having 90% of your system RAM unused.  8M is a
pain.  Difficult to install, annoying as heck to use
(swap...swap...swap...).  Given a choice between a 486/25 with 16M and
a P100 with 8M, I'd much prefer to use the 486 for OpenBSD.  

As for your second questionm, the issue isn't the bus, the issue is
the particular card (or, perhaps, its driver).  Some ISA cards work
great (3c509B), others vary widely (NE2000 compatables) and some most
likely stink (I found _pairs_ of 3c509(non-Bs) were horrible
performers in a 486/66, though singles NICs moved lots of data.  Not
sure what would happen in a P100 -- may be just fine).  Much the same
with PCI cards.  Some are highly regarded (Intel EtherExpress), others
I would never install in a client's system due to the nasty looking
console messages that regularly pop up on the screen (Realtek 8029
cards: "Ring buffer overflow", 3c905: "transmission error: 90", 10Mbps
de0 cards: "abnormal interrupt: receive process stopped") though I
haven't seen actual PERFORMANCE issues with any of these cards, in
spite of the messages.

Good PCI cards can (generally) move more data than the best ISA cards
due to better bus performance and lower processor impact when
accessing the bus.  Still, this is not a consideration for modest
links (and if you ask about an 8M system, I'm assuming you have a
"modest" link speed.  T1's are expensive, but they are only
1.5Mbps.).  If you wanted to put the resources where they count for a
"textbook" faster system, free up a PCI slot or two, using ISA video
and maybe even disk controller slots (if appropriate.  I haven't seen
too many PCI systems which only start with one slot, I'm guessing
there are others in your box, they are just in use).  Your video and
disk cards won't affect the performance of the firewall, the NICs
will.  However, this won't matter in real life unless you need a
100Mbps link to connect to the 'net, anyway (at which point, the issue
is moot anyway...you need a PCI bus to move that much data).

Nick.
-- 
http://www.holland-consulting.net/