Novell NSS (Novell Storage Services)

The Novell Storage Services (NSS) File System is the default file system for NetWare 6 and later. Its many features and capabilities include visibility, a trustee access control model, multiple simultaneous namespace support, native Unicode*, user and directory quotas, rich file attributes, multiple data stream support, event file lists, and a file salvage sub-system. These features can help you effectively manage your shared file storage for any size of organization, scaling management of the system for even the largest of organizations with hundreds of thousands of employees.

Benefits of NSS

Files are at the heart of every company, large or small. Whether your network spans continents or a few cubicles, your files become the foundation of your business. No one can afford unreliable file service, especially when the files you manage are continually growing and requiring more and more storage space.

Businesses today demand more storage space and faster and easier access to data. To meet the demands, you need a file system that can scale to a growing business, is easily maintained, and is better protected against corruption. NSS provides a variety of features that can be combined to provide a robust and reliable solution for your business.

NSS provides the following benefits:

• A journaling file system that lets you create bigger volumes that activate (mount) quicker, store more data, and better resist corruption
• An unlimited number of NSS volumes per NetWare partition
• Software RAIDs 0 (striping), 1 (mirroring), 5 (striping with parity), 10 (mirroring RAID 0 devices), and 15 (mirroring RAID 5 devices)
• Multiple server activation prevention (MSAP) to help protect pools from being concurrently activated by multiple servers that do not share a cluster relationship
• An NSS volume in a pool of storage that spans multiple storage devices
• Up to trillions of files in a single directory
• Faster access to data, regardless of file size or volume size
• Lower memory requirements: 1 MB of RAM can activate an NSS volume
• Directory space restrictions
• User space restrictions
• Salvage support for deleted volumes and files
• Multiple I/O path support
• Pool snapshots that capture point-in-time versions of files in the pool
• Encrypted volume support to meet the legal standard of making data inaccessible to software that circumvents normal access control, such as if the media were stolen
• Transaction Tracking System TM (TTS TM )
• CDs and DVDs automatically activated as NSS volumes
• CD and DVD image files activated as NSS volumes
• Novell Distributed File Services that allow you to move and split volumes to better manage storage growth

NSS is a 64-bit file system that can manage a virtually unlimited number of file objects. On each physical storage device, NSS abstracts up to four physical NetWare partitions to make them appear as contiguous free space. NSS recognizes physical and logical devices up to 2 TB in size from which you can create any number of virtual storage resources, called pools. You can choose space from at least four devices of up to 2 TB each to create a pool with a maximum pool size of 8 TB. A pool can contain an unlimited number of volumes. If the pool spans devices, the volumes automatically span the devices. A single volume can contain up to 8 trillion files and grow to 8 TB in size, depending on the size of the pool and space consumed by other volumes in the pool.

Storage Pools

During the NetWare installation, NSS automatically creates a system pool (sys) and an NSS volume (sys:) that can grow to the size of the pool. We recommend that you reserve the system pool and volume for operating system software and extensions. Create additional pools to effectively store applications, files, and databases.

You create additional storage pools by assigning areas of free space obtained from one or more of a server's storage devices. You can create one or more NSS volumes from the space in the storage pool. Figure shows how NSS uses free space on multiple devices to create a storage pool.

NSS Volumes

The logical volumes you create on NSS storage pools are called NSS volumes. You can specify a maximum storage quota for the volume, or allow the volume to grow dynamically to the size of its pool. You can add any number of volumes to a storage pool.

Because there is no limit to the number of volumes you can create, it is possible that the combined size of all the volumes taken together is larger than the storage pool itself. NSS refers to this process as "overbooking." If you overbook space in the pool, the individual administrative size of a volume cannot exceed the size of the storage pool.

NSS allocates space from the pools to the volumes only as needed. Typically, user consumption of a volume's available space ebbs and flows; it is quite unlikely that users concurrently consume volumes at 100% of their available capacity. Each volume consumes the space it needs as it needs it. By overbooking space, NSS provides a flexible and cost effective way to accommodate expanding storage needs.

For example, suppose you have a 300 GB storage pool. From this storage pool, you create two NSS volumes of 200 GB. You can define two 200 GB NSS volumes out of a storage pool of only 300 GB, if you feel comfortable that the NSS volumes will not both exceed 75 percent capacity (150 GB) and therefore, exceed the overall size of the storage pool. If one NSS volume does reach 150 GB, but the other volume stays under 100 GB, your overbooking plan worked.

Suppose you expect one of the volumes might exceed its share of the pool. You can overbook the pool by creating one NSS volume with a quota of 200 GB and a second NSS volume that can grow to the size of the pool. As the combined size nears the size of the pool, you can extend the size of the pool to allow more space for the larger, expanding volume. Your overbooking plan works because you built in the opportunity to expand the pool and volume, according to your business needs.