Error Recovery

Computers running any one of the Windows 2000 Advanced Server load balancing services are subject to the same risk of failure as other computers. Computers can fail for a variety of reasons, and it is always advisable to put safeguards in place against these potential points of failure whenever possible. These safeguards include software and hardware RAID, uninterruptable power supplies, and transaction logging and recovery, which is a feature of the NTFS file system. To make use of this feature, be sure to load the load balancing service on a partition formatted with NTFS.

With transaction logging and recovery, NTFS ensures that the volume structure will not be corrupted, so all files remain accessible after a system failure. NTFS also uses the recovery technique called "cluster remapping." When Windows 2000 Advanced Server returns a bad-sector error to NTFS, NTFS dynamically replaces the disk cluster that contains the bad sector and allocates a new disk cluster for the data. If the error occurs during a read, NTFS returns a read error to the calling program, and the data is lost (unless it is protected by RAID fault tolerance). When the error occurs during a write, NTFS writes the data to the new disk cluster, and no data is lost. NTFS puts the address of the disk cluster that contains the corrupt section into its Bad Sector file so that it does not reuse the corrupt section.

Even with transaction logging and recovery and disk cluster remapping, you can lose user data due to hardware failure if you do not use a fault-tolerant-disk solution.

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