Chart 8 - Concurrent Dumps Of Multiple Databases To 35/70 Dlt Tape Drives - Compaq 219700-001 - ProLiant - 1500 White Paper

Compaq Backup and Recovery for Microsoft SQL Server 6.x
The final point above deserves further discussion. When a single database is being dumped, the dump
process begins reading the data at the start of the database file and continues reading successive pages
that are stored more or less contiguously on disk (even in an array). When a second database residing
on the same disk or disk array begins, the disk heads will have to go back and forth between the two
locations, increasing seek time and slowing performance. Thus, the only way to retain steady,
sequential read paths is to isolate each database on its own volume. The only exception to this
principal, is for dumping two databases residing on the same mirrored (RAID-1) volume. In this case,
the Smart-2 SCSI Array controller can effectively keep the reads sequential on each set of mirrored
drives by using one set to satisfy read requirements of the first dump and the other set for the second
dump (known as "split seeks").
For the tests involved in this section, the system was configured as follows:
Y
A second Smart-2/P Array controller was installed in the system. A four spindle RAID-5 array

was created on each SCSI-port of both controllers, providing four logical drive volumes. Four
identical databases were then created, one on each drive volume.
Y
The four 35/70-GB DLT Tape drives configured across two Wide-Ultra SCSI controllers (2 drives

per controller) were retained from the previous tests. Thus there will be one tape drive to receive
data from each of the four databases.
Y
The controllers that will be sending data (the Smart-2 SCSI) are on the system's primary PCI bus,

and the controllers that will be receiving data (the Wide-Ultra SCSI) are on the second PCI bus.
This configuration is important to ensure load balancing so that PCI bus saturation will not be
encountered.
Using the above configuration, we performed dumps of from one to four databases simultaneously,
each to its own 35/70 DLT drive, while monitoring the usual hardware usage percentages. The results
are shown below:

Chart 8 - Concurrent Dumps of Multiple Databases to 35/70 DLT Tape Drives

The benefits of the concurrent dump strategy are quickly realized as additional databases are dumped.
When dumping one database to a single drive the throughput is 18.6 GB/hr, and when dumping two
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