12.1.5 Estimating the size of directories used by the audit trail facility
Estimate the size of the directories used by the audit trail facility based on the results of the estimations in 12.1.3 Estimating the size of audit trail data and 12.1.4 Estimating the compressibility of audit trail files. You also need to prepare the disks where the directories used by the audit trail facility will be created. You need to estimate the size of the following three directories:
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Audit trail directory
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Audit trail storage directory
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Audit trail long-term storage directory
The size of the output audit trail data and compressibility of audit trail files vary widely depending on the HADB server environment, and on the SQL statements, commands, and other operations executed by users. For this reason, you need to ensure the disks you prepare offer sufficient leeway over and above the values you estimate. Even if you use a disk with plenty of space, you must always keep an eye on the amount of free space on the disk while using the audit trail facility.
Take particular care to ensure that the disk containing the audit trail directory does not run out of space. The behavior of the HADB server when the disk that contains the audit trail directory runs out of space depends on which of the approaches you select in 12.1.7 Considering the approach to take when attempts to write to the audit trail file fail. You must therefore ensure that enough disk space is available to accommodate not only the data generated during normal operation, but also any data generated in relation to sudden and unexpected activity.
The following table shows an example of estimating the size of the directories used by the audit trail facility.
- ■ Conditions for estimation examples
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The audit trail facility outputs 864,005 KB (approximately 850 MB) of audit trail data per day to the audit trail file
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The audit trail files in the audit trail directory are moved to the audit trail storage directory once a day
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Audit trail files are kept for a total of 10 years
The audit trail files are kept in the audit trail storage directory for one year.
Those audit trail files are then stored in the audit trail long-term storage directory for a further nine years.
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The audit trail files in the audit trail long-term storage directory are compressed using the gzip OS command
The compressibility of the audit trail files is 0.25.
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The size estimated for each directory is the total of the minimum space required for the directory (required space) plus a certain amount of leeway (reserve space)
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|
No. |
Directory type |
Storage period for audit trail files |
Required space (GB) |
Reserve space (GB) |
Total space (GB) |
|---|---|---|---|---|---|
|
1 |
Audit trail directory |
1 day |
0.9 |
1.8 (equivalent to 2 days) |
2.7 |
|
2 |
Audit trail storage directory |
1 year (365 days) |
329 |
54 (equivalent to 2 months) |
383 |
|
3 |
Audit trail long-term storage directory |
9 year (3,285 days) |
740#1, #2 |
83 (equivalent to 1 year)#1 |
823 |
- #1
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This is the total size of the audit trail files after compression.
- #2
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The total size of the uncompressed audit trail files is approximately 2,957 GB.
In this example, the size of the disk you provide for each directory must be at least the total space estimated in the preceding table.