Andy said:
Thanks, I haven't considered DFS because I was unaware of
it. Is it only for server 2003 or is it available for
2000? Can you explain briefly how it works for fault
tolerance?
The server piece for DFS is available on both Windows 2000 and 2003. The
DFS client is installed by default on Windows 2000 and later, you can
download and install the client for 98, ME and NT4sp6.
From the FAQ:
Q. What happens when a root target or link target fails or is taken
offline?
A. If a DFS client attempts to access a previously used target, and
that target is unavailable, the DFS client works down through its referral
list for the next available target. This process is often referred to as
link target or root target failover. If the client reaches the end of the
referral list (that is, there are no available targets), the DFS client
fails the request.
Because stand-alone DFS namespaces can have only one root target, no
failover occurs if the stand-alone root server is not available; in that
case, clients cannot access the namespace.
For link target failover to work correctly, each link can have targets
that correspond to only one of the following locations:
a.. One or more shared folders.
b.. One or more stand-alone DFS paths anywhere in the stand-alone
DFS namespace, including the root.
c.. A single domain-based DFS path anywhere in the domain-based DFS
namespace, including the root.
For root target failover to work correctly, clients must access a
domain-based DFS namespace by using the format \\DomainName\RootName, not
\\RootServerName\RootName.
Q. What is DFS client "stickiness"?
A. When a client attempts to access a target in a namespace, the
client receives a list of targets, known as a referral. The client caches
the referral locally and attempts to access the first target in the
referral. If the first target is not available, the client attempts to
access the next target in the list and so on until the client finds an
available target.
After the client chooses an available target from the referral, the
client continues to access that target (either a particular root target or
link target) until one of the following occurs: the client computer is
restarted, the user clears the client cache (which discards all existing
referrals), or the Time to Live value for the root or link referral expires.
The client then obtains a new referral the next time it attempts to access
the target.
However, if the client continues to access the root or link within the
Time To Live value, the Time to Live value is renewed (in the locally cached
referral), and the client never requests a new referral. This automatic
renewal is referred to as "stickiness," and it applies also to clients that
are resuming from hibernation. Stickiness is an important consideration for
laptop computers that are taken from one site to another and are frequently
hibernated.
