Feature Article
NOVELL APPNOTES
October 2001
59
High Availability Networking with
NetWare 6: NSS 3.0 and Cluster
Services 1.6
Kevin Burnett
Senior Research Engineer
Novell AppNotes
[email protected]
One of the key benefits of Novell’s NetWare 6 is its ability to provide high
availability network services. The two main features here are Novell Storage
Services 3.0 and Novell Cluster Services 1.6, both of which are included with
NetWare 6. This AppNote provides technical detail on how these two services can
work together to give your users non-stop access to network resources and data.
Contents:
• Introduction
• Novell Storage Services 3.0
• Novell Cluster Services 1.6
• NSS and Clustering
•Conclusion
To p i c s file system, high availability, NetWare features, Novell
Cluster Services, Novell Storage System
Products NetWare 6, Novell Cluster Services
Audience network installers and administrators
Level beginner
Prerequisite Skills familiarity with NetWare
Operating System NetWare 6
Tools none
Sample Code no

instantaneous, and the amount of storage supported is virtually unlimited. NSS
gives you the ability to store large objects and large numbers of objects without
degrading system performance. It provides extremely fast access to your data.
NSS allows volumes to be mounted and repaired in seconds rather than the hours
it would take with NetWare’s traditional file system. And you get all of these
benefits while maintaining full backwards compatibility with classic NetWare.
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Benefits of NSS 3.0
This section describes the benefits of NSS in more detail.
Quick Access to Data.
Let’s assume that an intense electrical storm hits your site.
Unfortunately, you neglected to purchase that Uninterruptible Power Supply
(UPS) you’d been planning on buying for months. The power goes off for a
couple of minutes. Afterwards, when you reboot your server, one of the huge
server volumes needs to be repaired. With the traditional NetWare file system,
running VRepair could take hours to complete, since the amount of time required
to mount a volume is related to the size of the volume. With NSS, repairing an
NSS volume only takes minutes, regardless of size. Thanks to NSS and its
advanced journaling algorithms, volumes can be repaired quickly by replaying
uncommitted changes rather than scanning all the files on a voloume, as VRepair
did.
Improved Resource Use.
Consider a smaller-sized company with a stingy
hardware budget and an enormous new Web site to bring online. Imagine a server
with a limited amount of RAM available. It’s entirely possible that the volume
containing the Web site files won’t load because the server doesn’t have enough
memory to cache the entire directory entry table (DET).
NSS solves this and similar memory management problems by running on
virtually any amount of memory you have available. NSS mounts any size volume

Semantic Agents.
Figure 1: Structure of NSS.
Let’s discuss each of these layers in a little more detail.
Media Access Layer (MAL).
The MAL provides connection to a wide range of
storage devices such as standard hard drives, CD-ROMs, Digital Versatile Disk
(DVD) media, virtual discs implemented as networked clusters, and even
non-persistent media such as RAM disks. The MAL lets you view the storage
capabilities of your server as simply a quantity of storage blocks, freeing
administrators from the details of enabling various storage devices. The MAL’s
modular design allows new devices and technologies to be easily added. The
MAL also provides the interfaces used by the Object Engine to interact with the
available storage devices.
The Object Engine.
The Object Engine layer is the NSS object storage engine.
This engine differs from traditional object engines by providing significantly
higher levels of efficiency. The NSS Object Engine uses sophisticated and highly
efficient mechanisms to manage the objects it stores, achieving high levels of
performance, scalability, robustness and modularity.
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• Performance. To improve system performance, the Object Engine stores
objects on disk in balanced trees (sometimes called B-trees). Using the
compact B-tree structures guarantees the system can retrieve an object from
the disk in no more than four I/O cycles. B-trees also improve memory
management by letting the system locate an object anywhere in storage
without loading the entire directory entry table into memory.
The ability to share name spaces also improves disk space usage. Instead of
storing a name for each name space in a single stored object (such as one name
for DOS and another for UNIX/NFS), the name spaces in an object share a

new objects.