File Size Considerations

File system limitations:

• For a FAT 32 file system, the maximum file size is 4GB.
• Some UNIX systems have a large file support flag. Turn the flag ON to enable large file support. For example, AIX disables large file support by default, so the file size limit is 2GB.

One file size and security-related limitation:

For UNIX systems, set the file size limit for the root user account to unlimited in order to support large file support.

Example

Example Reference Table for Catalog Requirements shows backup schedules, retention times, and number of files for a group of example policies. By substituting the information from this table into the formula from step 3 above, we can calculate the maximum number of files for each policy. The following steps demonstrate this for policy S1:

1. Apply the following formula to policy S1:

   Max Files equals (Files per Incremental x Backups per Retention Period) + (Files per Monthly Full Backups x Backups per Retention Period)

2. Substitute values from Example Reference Table for Catalog Requirements:

   1000 files x 30 + 64,000 files x 12 = 798,000 files

   Perform steps 1 and 2 for each policy. Adding the results together shows that the total number of files for all policies is:

   4,829,600 files

   Multiply the total number of files by the bytes in the average path length and statistics (100 for this example). The total amount of disk space required for file paths is:

   460.59 megabytes (1,048,576 bytes in a megabyte)

   Adding 15 megabytes for error logs results in a final uncompressed catalog space requirement of:

   475.59 megabytes

   Example Reference Table for Catalog Requirements 

   Policy	Schedule	Backup Type	Retention	Number of Files
   S1	Daily Monthly	Incremental Full	1 month 1 year	1000 64,000
   S2	Daily Monthly	Incremental Full	1 month 1 year	1000 70,000
   S3	Daily Weekly Monthly	Incremental Full Full	1 week 1 month 1 year	10,000 114,000 114,000
   S4	Daily Weekly Monthly Quarterly	Incremental Full Full Full	1 week 1 month 3 months Infinite	200 2000 2000 2000
   WS1	Daily Monthly	Incremental Full	1 month 1 year	200 5600
   WS2	Daily Weekly Monthly	Incremental Full Full	1 week 1 month 1 year	7000 70,000 70,000