If you can estimate the maximum number
of files that might be in server storage at a time, you can use that
number to estimate space requirements for the database.
About this task
To estimate
space requirements that is based on the maximum number of files in
server storage, use the following guidelines:
In the following example for a single client,
the calculations are based on the maximum values in the preceding
guidelines. The examples do not take into account that you might use
file aggregation. In general, when you aggregate small files, it reduces
the amount of required database space. File aggregation does not affect
space-managed files.
Procedure
- Calculate the
number of file versions. Add each of the following values to obtain
the number of file versions:
- Calculate the number of backed-up files. For
example, as many as 500,000 client files might be backed up at a time.
In this example, storage policies are set to keep up to three copies
of backed up files:
500,000 files * 3 copies = 1,500,000 files
- Calculate the number of archive files. For
example, as many as 100,000 client files might be archived copies.
- Calculate the number of space-managed files. For example, as many as 200,000 client files might be migrated
from client workstations.
Using 1000 bytes per file, the total
amount of database space that is required for the files that belong
to the client is 1.8 GB:
(1,500,000 + 100,000 + 200,000) * 1000 = 1.8 GB
- Calculate the number
of cached files, copy storage-pool files, active-data pool files,
and deduplicated files:
- Calculate the number of cached copies. For example, caching is enabled in a 5 GB disk storage pool.
The high migration threshold of the pool is 90% and the low migration
threshold of the pool is 70%. Thus, 20% of the disk pool, or 1 GB,
is occupied by cached files.
If the average file size is about
10 KB, approximately 100,000 files are in cache at any one time:
100,000 files * 200 bytes = 19 MB
- Calculate the number of copy storage-pool files. All primary storage pools are backed up to the copy storage
pool:
(1,500,000 + 100,000 + 200,000) * 200 bytes = 343 MB
- Calculate the number of active storage-pool files. All the active client-backup data in primary storage pools
is copied to the active-data storage pool. Assume that 500,000 versions
of the 1,500,000 backup files in the primary storage pool are active:
500,000 * 200 bytes = 95 MB
- Calculate the number of deduplicated files. Assume
that a deduplicated storage pool contains 50,000 files:
50,000 * 200 bytes = 10 MB
Based on the preceding calculations, about
0.5 GB of extra database space is required for the client’s cached
files, copy storage-pool files, active-data pool files, and deduplicated
files.
- Calculate
the amount of extra space that is required for database optimization. To provide optimal data access and management by the server,
extra database space is required. The amount of extra database space
is equal to 50% of the total space requirements for file objects.
(1.8 + 0.5) * 50% = 1.2 GB
- Calculate the total amount of database
space that is required for the client. The total is approximately
3.5 GB:
1.8 + 0.5 + 1.2 = 3.5 GB
- Calculate the
total amount of database space that is required for all clients. If the client that was used in the preceding calculations
is typical and you have 500 clients, for example, you can use the
following calculation to estimate the total amount of database space
that is required for all clients:
500 * 3.5 = 1.7 TB
Results
Tip: In the preceding examples,
the results are estimates. The actual size of the database might differ
from the estimate because of factors such as the number of directories
and the length of the path and file names. Periodically monitor your
database and adjust its size as necessary.
What to do next
During normal operations, the
Tivoli® Storage
Manager server might
require temporary database space. This space is needed for the following
reasons:
- To hold the results of sorting or ordering that are not already
being kept and optimized in the database directly. The results are
temporarily held in the database for processing.
- To give administrative access to the database through one of the
following methods:
- A DB2® open database connectivity
(ODBC) client
- An Oracle Java™ database
connectivity (JDBC) client
- Structured Query Language (SQL) to the server from an administrative-client
command line
Consider using an extra 50 GB of temporary
space for every 500 GB of space for file objects and optimization.
See the guidelines in the following table. In the example that is
used in the preceding step, a total of 1.7 TB of database space is
required for file objects and optimization for 500 clients. Based
on that calculation, 200 GB is required for temporary space. The total
amount of required database space is 1.9 TB.
Database size |
Minimum temporary-space requirement |
< 500 GB |
50 GB |
≥ 500 GB and < 1 TB |
100 GB |
≥ 1 TB and < 1.5 TB |
150 GB |
≥ 1.5 and < 2 TB |
200 GB |
≥ 2 and < 3 TB |
250 - 300 GB |
≥ 3 and < 4 TB |
350 - 400 GB |