Objectives:This chapter discusses management of Novell Storage Services (NSS). The objectives important to this chapter are:
Concepts:Expand an NSS Storage SpaceNovell Storage Services (NSS) is an enhanced, improved file system, compared to previous versions of NetWare. Chapter 5 tells us that we can manipulate NSS storage to our benefit, if we observe the limits as well. You should recall that NSS locates available space on storage devices and logically stores it in a pool. The hard drive partitions that hold the space must be NSS partitions. You can have several partitions, and several pools, but each partition can belong to only one pool. NSS volumes are created from the storage space in the pool. Up to 255 logical volumes can be created in a pool, but the text cautions us that each user can only have up to 26 drive mappings, including the letters mapped to local devices. A volume in a storage pool cannot contain more space than the pool contains. However, each volume in a pool is allowed to be configured to contain all the storage space in the pool. This would make the total space allocated to the volumes larger than the pool itself. This is really a theoretical limit to the volume size, since you cannot use the same space in two volumes at the same time. It does, however, give you the ability to assign all available space in a pool to each volume in it, which would allow any of the volumes to grow as large as they need to be, up to the limit of actual space. If you do not know how large a volume will actually need to be, this feature could be helpful. The practice of assigning space this way is called overbooking. If you need more space in a storage pool, you can add more hard drives to it. Be aware that you cannot take space away from a pool without recreating it. The basic procedure is to add a new drive, create one or more NSS partitions on it, then add the new partition to the pool with ConsoleOne, Remote Manage, or NSSMU (a console utility). Configure NSS Volume AttributesNSS volumes have a large set of attributes which can be set as options. The text warns that you should not turn on attributes that you do not need, because they can reduce performance of the volume.
One feature is described that applies to pools (and their volumes): Sharable for Clustering. This allows the pool and its volumes to be shared on a clustered device. Mount a DOS Partition as an NSS VolumeThe ability to mount a DOS partition as an NSS volume is meant for support of core dumps. The feature supports removable media, assignment of Novell rights to the media, drive mapping, and management of the volume with standard NetWare tools. The text warns us that this feature is not to be used for file storage by users. The implication is that it is not reliable enough for normal file storage. This feature is mad possible by an NSS module, DOSFAT.NSS. The DOS partition in question must use FAT16 (16-bit File Allocation Table) or FAT12, a File Allocation Table system seen on floppies and old, small hard drives. DOSFAT.NSS supports these features:
To make the use of DOSFAT.NSS practical, the text recommends turning off the automatic restart after abend feature. Leaving this feature on would probably corrupt the FAT table on your hard drive, since the automatic restart would take place during the write procedure for your ABEND.LOG file on the DOS partition. Loading DOSFAT.NSS will cause a volume name to be assigned to the DOS partition. Assuming that it is on your C: drive, the volume name will probably be DOSFAT_C. If NSS is not aware of the drive letter for your DOS partition, the name may be DOSFAT_0 or DOSFAT_1. The name and status of the volume can be verified with the VOLUMES command at the server console. Use VCU to Create an NSS Volume from a Traditional Netware VolumeThe text states that you can convert traditional volumes to NSS volumes with the VCU, Volume Conversion Utility. Note, however, that the process as described is similar to a server migration: you are actually copying the data from a traditional volume to a logical NSS volume. It is not actually a conversion. It is safer than a real conversion process might be, since you don't have to delete the original volume immediately. A potential problem is that you need to have enough space on the disks to hold both the old and new volumes for this process to work. Also, older NetWare systems (pre-dating NSS) will not be able to access the new NSS volume (or any NSS volume). VCU is run from a server console. It has several command line parameters,
listed in the text. The simplest form of use is just to enter the command,
followed by the name of the existing volume, followed by the name of the
new NSS volume. A previous term's text warns us that this command is likely to produce an error message on its results screen. This is because the traditional volume contains a hidden file, not needed by the NSS volume, that is not copied to the NSS volume. On that results screen, you are asked a question.
The recommended procedure is to check for errors, and delete the original volume when you are sure the NSS copy is usable. Resolve Common NSS ErrorsTroubleshooting NSS errors is similar to troubleshooting other Novell errors. An error message number should lead you to a proposed solution. Before applying a solution, however, verify that the problem that actually exists is the one reported. Sometimes an error can be due to hardware or memory problems.
Traditional volumes can be maintained with the VREPAIR utility.
NSS pools and volumes use VERIFY to check their integrity, and sometimes
use REBUILD to repair them. This should be
done as a diagnostic and as a maintenance procedure. The command to verify
a pool, oddly enough, is not VERIFY.
It is: After diagnosing your problem, assess possible solutions as you would for eDirectory problems. Decide which solution or solutions to try, based on likelihood of success, your experience, and the advice of others. Backups may provide a solution, if they were made in a time frame that is helpful to you. A possible restorative solution to file system problems is the REBUILD utility.
The text warns us that this utility might also cause damage to the file
system. Restoring from tape backups is recommended before considering
using REBUILD. If you run REBUILD, all users must be off the pools and
volumes being rebuilt. You can get them off by deactivating the pools.
The text offers only the syntax for a command to rebuild a pool, not
a volume: You should use the VERIFY utility after using the REBUILD utility. You will also have to mount the volumes again before they can be used. If data that you must have cannot be recovered by any of these methods, there is the possibility of hiring professionals in this field. This is usually expensive, and the cost should be weighed against the loss of the data. Restore a Deleted Logical VolumeNovell's heading for this objective is misleading: you don't restore files and volumes, you salvage them. Salvaging NSS volumes is a little different from salvaging traditional volumes. First, if a pool has been deleted, all volumes in that pool are gone, and they cannot be salvaged. Second, if a volume itself has been deleted, that volume may be salvaged if the purge delay time has not expired. Purge delay time is set to two days by default. NSS deletions older than the purge delay time are automatically purged by the system. The automatic purge can be avoided two ways, using ConsoleOne.
Describe Storage Area Networks and Network Attached StorageStorage Area Networks (SANs) are separate networks created just for file storage. Network Attached Storage (NAS) is a storage component of your own network. Both can let you use a Redundant Array of Independent Disks (RAID) for fault tolerant storage. The two technologies can be used together, if you need to do so. A SAN is set up as a separate network accessible from your network. This means that performance of the SAN will not be affected by network traffic on your network. A SAN is accessed by either a Fibre Channel or a SCSI connection, to provide high bandwidth and reliability. These channels do not use the same TCP/IP protocols as your network. In our lab at school, we have found that the SAN server must be booted up first, then the Novell server used to access the SAN. A SAN has five components:
NAS is a product made available on your network. Other network traffic will affect performance of NAS. NAS is sometimes referred to as a NAS appliance. NAS uses the same protocols as the rest of your network. Like SAN, NAS is meant for storage only, not application or other services. NAS is meant for immediate access by users, SAN seems more oriented to backups. |