HP 9000 rp5405 Servers - Manual (Page 63)

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 Table 2 . For best results, collect the data
from your database server with the largest configuration.
2. Calculate the time necessary to back up a database using this formula:
DB_BACKUP_TIME = {( IS / IS_VERIFY ) * IS_NUM + ( LOG_NUM / LOG_VERIFY )} * SG_NUM
+ RESYNC_TIME
NOTE:
Because the variables IS_VERIFY and LOG_VERIFY are highly dependent on server and
storage I/O performance, actual values are difficult to obtain. For best results, use the
assumed values supplied.
3. Compare the time allowed for the backup process with the time required to back up a database
server:
• If the SYSTEM_BACKUP_TIME value is less than or equal to the DB_BACKUP_TIME value,
decrease the number of storage groups and/or information stores per database server and
repeat the calculation in step 2.
• If the SYSTEM_BACKUP_TIME value is greater than the DB_BACKUP_TIME value, calculate
the number of backup servers using the following formula:
BK_SERVER = DB_SERVER / VERIFY_PARA
Round this value to the nearest whole number.
Table 2 Parameters for backup server calculations
Notes Description Parameter
You must supply this value.
Size of a the database file per inform-
ation store to be backed up (MB)
IS
You must supply this value.
Number of transaction log files per
storage group to be backed up
LOG_NUM
You must supply this value.
Number of information stores per
storage group (Exchange Server
2003/2007), or per database server
(Exchange Server 2010)
IS_NUM
User Guide 63