HP ProLiant 1500 Compaq Backup and Recovery for Microsoft SQL Server 6.X - Page 47

Compaq Backup and Recovery for Microsoft SQL Server 6.x Page 47 Server backup functionality, with 15/30-GB DLT's. From the above chart, we see that this is not the case with the 35/70-GB drives (compare to Chart-7). Using ARCserve yields good backup performance and scaling up to the second drive; after that almost no further gains are realized with additional drives. The reasons for this performance "flat-line" come down to the high CPU utilization demanded by the database backup agent and SQL Server when performing this type of a database dump. Saturation of the system processors restricts the backup throughput to around 38 GB/hr with RAID-0 and 34 GB/hr with RAID-5, and interferes with the system's ability to process other activity (such as user transactions on another database) for the duration of the backup job. Given these results, it would follow that no more than two 35/70 DLT drives should be used in a database backup to an ARCserve RAID-0 tape array, and no more than three such drives in a RAID-5 tape array. Note however, that a system with more powerful processors than our four Pentium-Pro/166 modules, could conceivably yield better performance with more drives. Finally, it should be noted that we did not attempt to test a scenario involving concurrent backups of multiple databases to storage on the local server using ARCserve for Windows NT, due to the high CPU use. We do however, recommend ARCserve (and its autochanger option) for implementing concurrent, unattended backup jobs to both drives inside the Compaq DLT 15-Cartridge Library69. Also, results of using the ARCserve products to perform concurrent backups of databases to a remote server, will be shown in the following sections. 69 CPU usage for such a scenario would not be expected to exceed around 50% in a 4P/166 Proliant 5000. 1997 Compaq Computer Corporation, All Rights Reserved Doc No 444A/0797