Frank queries:
> Does anyone in the world use an HP3000 as a file server? How would it
> be done (with out reference to POSIX)? Didn't hp sell them as
> that? Please respond - were dying over here.
People use HP3000s as "Servers" but rarely as "File Servers", where "File
Server" implies something like a traditional PC file server running an OS
designed for this purpose, such as Netware, Vines, or even Windows NT.
Computer systems are designed by people who generally only see part of
the applications space. Some systems will later evolve to successfully
do things that they weren't originally designed to do, but for the most
part a particular system has something that is does well and a lot of
things it doesn't do well.
The HP3000 excels at being a multi-user transaction processing engine.
UNIX excels at processing text files.
PC file servers excel at serving up data and program files to a PC
client.
HP3000s make really lousy PC file servers. UNIX systems make relatively
lousy PC file servers. PC file servers make really excellent PC file
servers.
Products like Resource Sharing, Netware/iX, Samba, and the like exist on
HP3000s and UNIX for a number of reasons. Yes, there has been a lot of
development done by people who thought that they could produce a viable
*alternative* to a PC server, but few customers have bought into this
idea. On the other hand, the fact that your PC clients can access data
on the 3000 exactly the way they access data on your *real* file servers
is an extremely powerful idea. Something like Samba enables the creation
of all sorts of applications that would otherwise be much more difficult
to build. But in these applications you find Samba only being used to
access the data on the 3000 (or UNIX for that matter) that is there for
other reasons. Anything that doesn't *have* to come from the Samba
server probably *shouldn't* come from there, but should come from a local
disk or a "real" PC file server.
A "real" file server like Netware is an operating system designed to
do one or two things really well, and others not at all. Netware's
claim to fame is fast network I/O and intelligent file caching. That's
it. A big Netware server can respond to something like 10,000 network
packets per second because that's what the system was built to do.
The performance of something trying to be something it's not will
generally not be very good, and all PC server type programs I've ever
seen on the 3000 have been good examples of this. I was at Quest when
we did the port of Novell's "Portable Netware" product to MPE/XL which
became the Netware/iX product. One of the big problems with making a
general purpose system into a PC-like file server is the network I/O
performance. Typically a packet comes in to a lan interface card, then
an interrupt is generated, the system I/O driver accepts the data from
the lan card, the network protocol stack runs to decide who to give the
message to, that process is scheduled for execution, and the system
goes back to whatever it was doing. Eventually the server code runs, gets
the message from the network transport, processes it, produces a response,
sends the response to the network transport (i.e. sockets) which copies
it into a network buffer and queues it to go out the lan card. That's
how it works on a 3000 and most UNIX systems. On a Netware system,
there are none of these layers to get in the way. The server software
can start processing a request as soon as the first bits of the packet
reach the lan card in some cases. By the time the last bit has arrived
at the lan card, the response may already be ready to go. There are no
interactive users, batch processes, etc. to get in the way either.
With Netware/iX, the developers eventually went to the point of guessing
what data the PC client would ask for next, freezing it into memory, and
hooking Netware code into the lan driver so that it could actually send
a response to a request while still processing the interrupt from the
incoming request (all running on the Interrupt Control Stack). Even after
all this, the 3000 still could out perform only a relatively low powered
Native Netware server.
Even if you could get your HP3000 or UNIX system up to the performance of
a PC based server, it would be hard to justify the cost, since a $2000 PC
with a 200Mhz CPU, 64Mb of memory, and fast lan card would need the
largest mainframe class UNIX or MPE system to compete against it if
Samba is your application. On the other hand, you can take a little
48Mhz HP3000 and put 100 users on it all pounding transactions through
it which is something that no PC operating system can yet support, no
matter how fast the PC is.
Does this mean that Samba etc. are not useful? Of course not. As noted
above, there are vast numbers of uses for something like Samba on a 3000.
for example, I can do application development in Java from my PC, using
a PC-based graphical Integrated Development Environment, using Samba
to allow me to access my source code that is on the 3000, write the
compiled code directly back to the 3000 into a directory where the code
can be executed as a local application using the Java VM and Just in Time
compiler on the 3000, or immediately served up as a web applet using
the Apache WWW server back to my web browser.
In the case at hand, none of this is of any use to you of course. In short
answer to your questions, no, very few people use a 3000 as a replacement
for a PC file server, and no, HP generally does not sell the HP3000 for
this purpose. If someone sold you an HP3000 as a server to hook a bunch
of PCs to and all the PCs data and programs are going to be downloaded
from the 3000 using Samba or some other 3000-based PC style server program,
then in my opinion you were not given good advice. Also, as has been
pointed out, Samba for the 3000 should be considered prerelease "beta"
quality software at the moment, which few people would run in a production
environment, and has known performance deficiencies.
G.
|
