Re: [SLUG] Win4Lin vs VMWare

[Del <del@nospam.babel.com.au>]

Just my own 2c on the two products:

I originally bought VMware because it enables me to do things on
one machine that I previously required an entire network for,
eg: setting up a NetWare server, joining NT machines to the NetWare
tree, testing NT servers, testing NT workstations joining a SAMBA
domain, etc.  This is its primary purpose for me, the fact that it also
allows me to run Windoze apps on my Linux PC is a bonus.

Win4Lin doesn't do that, it basically runs a "legless" copy of
Windows 95/98 (not NT or 2000) in a window under X.  It runs most,
but not all, Win32 applications in this box.  From the outside,
both programs look similar, in that they are running a 'doze
environment in a box, but Win4Lin is significantly faster.  Inside,
however, they take quite different approaches.

VMware emulates an entire machine.  Booting a VMware window involves
giving it RAM, letting it boot its BIOS, loading the OS, and running
from there.  Booting Win4Lin involves starting the OS only, over the
driver layer provided by Win4Lin and Linux.  This means that VMware
can run (theoretically) any i386 operating system, whereas Win4Lin only
runs 95 and 98, which are the two OSes that it provides a device
driver layer for.

They also take a different approach to networking.  Each VMware machine
has its own virtual network card, IP address, MAC address, etc.  It appears
on the LAN as a unique machine.  Inside the VM, any network protocol
supported by the loaded OS can be run (IPX, TCP/IP, LAT, NetBEUI, etc).
The Win4Lin machine appears to be the same IP address as the host PC,
and can run TCP/IP only.  Also, because it runs at the same IP address,
there are some TCP/IP things that it can't do, including run some types
of servers.  It can't run a server on the same port number as a port
being used on the host Linux machine, for example.

The different networking approach is what causes the main difficulties
with Win4Lin.  For example, SQL server won't run on it, neither will
the Microsoft Data Engine (as far as I can tell).  This in turn means
that MSDE applications, such as Visio 2000 enterprise edition won't
run.

The two programs also take a different approach to sharing files.  VMware
has a virtual disk for each VM, which appears as a single monolithic
file on Linux, and is limited to 2GB.  To share files between a VM
running NT and the host Linux system, you need to set Linux up as a
SAMBA server and share these files using the SMB (networking) protocol.
Win4Lin uses a directory ($HOME/win) in each user's home directory to
represent the Windows C: drive, and files in that area area are shared
between Linux and Windows.  The Win4Lin documentation does state, however,
that these files should not be used by Linux while Win4Lin is running,
because of the buffering algorithms used (and presumably, Win4Lin does
no file locking).

The Win95/98 directory tree used by Win4Lin is self contained.  That means
that, having built the tree and then shut Win4Lin down, the tree can be
replicated across systems using tar/cpio or similar methods.  One limitation
is that the tree cannot be shared across NFS links (this is rather serious
in an enterprise environment as it limits the ability for each user to have
a "roving desktop" shared from a central NFS server).  This allows the
fast rollout of Win95/98 desktops and applications to a group of Linux
systems.

The VMware disk image is similarly self contained, however as it will contain
machine specific information (eg: machine name, SID, and IP configuration), it
can't be rolled out cleanly across an enterprise except with the use of
tools which can replace the machine name and SID part at the least.  VMware
disk images can be shared across NFS, however (VMware warn against doing this
for performance reasons but on a fast NFS server on a fast network I have
done this successfully).

Overall, for running most Windows 95/98 applications Win4Lin is a better
choice, if only for peformance reasons.  For the serious network user,
however, VMware provides an environment with more features and flexibility.

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Del | mailto:del@nospam.babel.co.nz | Christchurch, New Zealand
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