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NetBackup System Administrator’s Guide - Windows NT Server
5
If a weekly full backup schedule backs up 3000 files for all its clients and
the retention period is four weeks, the maximum number of files due to
weekly-full backups that can exist at one time are:
3000 x 4 weeks = 12,000
Obtain the total for a server by adding the maximum files for all the
schedules together. The maximum number of files that can exist at one time
due to the above two schedules is the sum of the two totals, which is 20,400.
Note:
For classes that collect true-image-restore information, an incremental
backup collects catalog information on all files (as if it were a full backup). This
changes the above calculation for the incremental from 1200 x 7 = 8400 to 3000
x 7 = 21,000. After adding 12,000 for the fulls, the total for the two schedules is
33,000 rather than 20,400.
4. Obtain the number of bytes by multiplying the number of files by the
average length of the file’s full pathnames and file information. If you are
unsure of the length, use 150 (averages from 100 to 150 are common). Using
the results from the examples in step 3, yields:
(8400 x 150) + (12,000 x 150) = 2988 kilobytes (1024 bytes in a kilobyte)
Note:
If you use database indexing, multiply the number in Step 4 by 1.5%
(see “Indexing the Image Database to Reduce Restore Times” on page 217).
5. Add 10 to 15 megabytes to the total calculated in step 4. This is the average
space for the error logs. Increase the value if you anticipate problems.
6. Allocate space so all this data remains in a single partition.
EXAMPLE
Table 4 shows backup schedules, retention times, and number of files for a
group of example classes. By substituting the information from this table into
the formula from Step 3 above, we can calculate the maximum number of files
for each class. Step 1 and Step 2 below demonstrate this for class S1:
1. Applying the formula to class S1:
Max Files equals:
(Files per Incremental x Backups per Retention Period)
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT
