IBM E16RMLL-I Implementation Guide - Page 71

Database size

Page 71 highlights

As with any database, the faster the disk used for the database the better. Spreading the database over as many physical disks as possible allows for better performance because multiple disk heads can be seeking, reading, and writing simultaneously. Counter to conventional thinking, however, several design ideas are peculiar to Tivoli Storage Manager. First, our lab measurements and client experiences have shown Tivoli Storage Manager internal software database mirroring to be a very efficient means of providing database redundancy-often more so than hardware redundancy. And finally, due to locking and threading information in the Tivoli Storage Manager server code, smaller logical database volumes tend to perform better than the larger ones. This is primarily due to Tivoli Storage Manager server code locking and threading considerations. 2.8.4 Database size To estimate the Tivoli Storage Manager database size for backup data, use the data collected in Table 2-1 on page 18 and Table 2-5 on page 26. The calculation is based upon the actual number of file versions backed up. If this is not known, you can estimate 5% of the amount of data backed up for the primary storage pool and 1% for copy pools. 1. Sum the Number of Files Backed Up field for all clients. 2. Multiply this number by the number of versions kept, giving a total number of files backed up. 3. Multiply this number by 600 bytes, to give bytes used in the database for all known files backed up. 4. If copy storage pools are used (and we strongly recommend this), multiply the total number of files backed up and calculated in step 2 above by 200 bytes, giving the bytes for known copy storage pool files. 5. Add the bytes for known copy storage pool files to the estimated bytes for copy storage pool files to give the total bytes for copy storage pool files. 6. Add the total bytes for backed up files to the total bytes for copy storage pool files to give the total bytes calculated for the database. 7. Calculate 135% of the total bytes calculated for the database to give the database size. This is for overhead and for growth. Chapter 2. Implementation planning 41

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Chapter 2. Implementation planning
41
As with any database, the faster the disk used for the database the better.
Spreading the database over as many physical disks as possible allows for
better performance because multiple disk heads can be seeking, reading, and
writing simultaneously.
Counter to conventional thinking, however, several design ideas are peculiar to
Tivoli Storage Manager. First, our lab measurements and client experiences
have shown Tivoli Storage Manager internal software database mirroring to be a
very efficient means of providing database redundancy—often more so than
hardware redundancy.
And finally, due to locking and threading information in the Tivoli Storage
Manager server code, smaller logical database volumes tend to perform better
than the larger ones. This is primarily due to Tivoli Storage Manager server code
locking and threading considerations.
2.8.4
Database size
To estimate the Tivoli Storage Manager database size for backup data, use the
data collected in Table 2-1 on page 18 and Table 2-5 on page 26.
The calculation is based upon the actual number of file versions backed up. If
this is not known, you can estimate 5% of the amount of data backed up for the
primary storage pool and 1% for copy pools.
1.
Sum the Number of Files Backed Up field for all clients.
2.
Multiply this number by the number of versions kept, giving a total number of
files backed up.
3.
Multiply this number by 600 bytes, to give bytes used in the database for all
known files backed up.
4.
If copy storage pools are used (and we strongly recommend this), multiply the
total number of files backed up and calculated in step 2 above by 200 bytes,
giving the bytes for known copy storage pool files.
5.
Add the bytes for known copy storage pool files to the estimated bytes for
copy storage pool files to give the total bytes for copy storage pool files.
6.
Add the total bytes for backed up files to the total bytes for copy storage pool
files to give the total bytes calculated for the database.
7.
Calculate 135% of the total bytes calculated for the database to give the
database size. This is for overhead and for growth.