Performance

This section reports the results of our experiments to quantify the achievable performance of the physical and logical backup and recovery strategies. We begin by reporting the performance of the most straightforward backup and recovery plans, and then proceed to measure the speedup achievable by utilizing multiple tape devices.

All of our measurements were performed on eliot, a Network Appliance F630 file server. The filer consists of a 500 MHz Digital Alpha 21164A processor with 512 MBytes of RAM and 32 MBytes of NVRAM. 56 9 GByte disks are attached via a Fibre Channel adapter. 4 DLT-7000 tape drives with Breece-Hill tape stackers are attached through dedicated Differential Fast Wide SCSI adapters. At the time the experiments were performed, the filer was otherwise idle.

The 481 GBytes of disk storage are organized into 2 volumes: home which contains 188 GBytes of data and rlse which contains 129 GBytes of data. The home volume consists of 31 disks organized into 3 raid groups and the rlse volume consists of 22 disks organized into 2 raid groups. Both the home and rlse file systems are copies (made using image dump/restore) of real file systems from Network Appliance's engineering department.