HP XP Racks User Manual
Page 66
Parallel verification count and number of backup servers
The parallel verification count controls the number of hosts that can perform backup verifications
simultaneously. The default value is 1, meaning that when executing a backup for one backup server
with multiple database servers at the same time, all concurrent backups remain in standby until the
backup for each database server is finished. The parallel verification count (known hereafter as parallel
count) can be increased, but there are performance considerations.
You can also use the parallel verification count in a calculation to determine the number of backup
servers necessary. See
Estimating the number of backup servers
for more information.
Parallel performance
The verification performance is dependent on S-VOL disk I/O, which is in turn dependent on the
following devices:
•
HBA of the backup server performing the verification
•
FC-SW used between the backup server and storage
•
Storage port, controller, and disk
When setting the parallel count to 2 or more, you need to increase the number of disk I/O paths
between the backup server and storage and distribute the disk I/O load from the S-VOL of each
database server to prevent performance bottlenecks in the above devices.
HP recommends setting the parallel count to a value at or below the number of disk I/O paths on the
backup server. However, if the parallel count is increased but the disk I/O becomes concentrated
and performance bottlenecks occur, the performance of the verification process may not increase.
Increasing the number of FC ports
When performing a concurrent execution of the verification process, disk I/O creates the greatest
performance bottleneck.
During the verification process, even if the process for one FC port is multiplexed, the performance
of the I/O that can be processed by that FC port is limited to the bandwidth of the FC port even at
the maximum value.
Therefore, to execute the verification process in parallel and increase the performance, it is ideal to
increase the number of FC ports connecting the server and storage and provide a configuration to
enable multiple processing of I/O with respect to the disk.
The number of FC ports that can be mounted on one server is as follows:
number-of-FC-ports
=
number-of-FC-ports-per-HBA
*
number-of-expansion-slots-that-can-be-used-to-mount-HBA
Estimating the number of backup servers
You can use the following procedure (a series of calculations) to estimate the required number of
backup servers necessary for efficient backup operations.
1.
Collect/estimate values for all the parameters shown in
. For best results, collect the data
from your database server with the largest configuration.
Setting up information sources
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