Backup has traditionally been serial in nature. While this approach was acceptable in the past, it is certainly not effective as today’s backup involves several terabytes of data and tape devices are able to service several megabytes of data per second. In addition to this, file systems are generally optimized for servicing multiple client requests simultaneously. The serial nature of backup thus limits the optimal usage of the file system characteristics.
The target service agent (TSA) functions as a library that provides any service the backup engine demands. The TSA available on NetWare 6.0 or lower reads files based on engine requests and blocks till the file system services the read request. Due to this, the backup engine is unable to keep data streaming to the tape device that would allow the device to perform optimally. While the TSA library model does not limit or prevent simultaneous access to multiple files, it has traditionally been used in a serial manner that has effectively reduced the throughput of the backup system.
The Target Service Agent for NetWare 6.5 and Linux (TSAFS) have been designed to deliver performance within the parameters of the current model of usage.