Gavin Scott writes:

> 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.

A quite excellent response, Gavin.

Wirt Atmar