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Re: Laptops as servers?
From: David Charlap <david.charlap () marconi com>
Date: Thu, 15 Jun 2000 09:52:59 -0400


Jerry Scharf wrote:

One thing I know to watch for is periodic battery replacement. It
turns out that running a laptop with a battery in it with AC on all
the time will slowly erode the life of the battery. I have no way to
know how long you can do this before the batteries won't do what you
were expected.

As a single data-point, I have a 3.5-year-old old Dell Pentium-150
laptop in my office that is almost always running off of AC.  AFAIK, it
is still on the original battery.  According to the Windows APM battery
meter, it won't hold a charge beyond 85% of capacity.  When I run it on
battery, I get about 45-60 minutes before the low-battery warnings go
off.

The other is that the I/O on laptops sucks compared to PCI. For things
that aren't major traffic handlers (like your DNS and DHCP examples)
this is not a hit. Do any of the O/Ss out there get full rate out of a
100bT PC card?

According to http://www.pcmcia.org/papers/new_bus.htm (a white-paper on
CardBus from 1997), an old-standard (PC Card-16) slot is 8- or 16-bits
wide at 8MHZ - similar bandwidth as an ISA slot.

The newer CardBus standard allows for a 32-bit channel (muxed address
and data) at 33MHz - for a theoretical top speed of 132M/s, similar to
32-bit PCI.  CardBus also supports bus-mastering, whereas PC Card-16
does not.

IOW, it should be possible for a CardBus (but not PC Card) device in a
CardBus-compatible PCMCIA socket to get equivalent performance to a PCI
card.  I have no clue, however, whether vendors are actually shipping
devices that actually make use of all this.

-- David



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