· May 11, 2023 2m read

How to estimate backup size for online backup

InterSystems FAQ rubric

You can use the system routine ^DBSIZE to estimate the backup file size (see also Note 1).

^DBSIZE estimates the file size of full, cumulative, and differential backups of the databases selected in the database backup list.

The database backup list is created from [System Administration] > [Configuration] > [Database Backup] > [Database Backup List] in the Management Portal.

For more information, please refer to the document below.

Estimate backup size with ^DBSIZE [IRIS]

Estimate backup size with ^DBSIZE

An execution example is as follows.

USER>set $namespace="%SYS"   //or zn "%SYS"
               Incremental Backup Size Estimator
What kind of backup:
   1. Full backup of all in-use blocks
   2. Incremental since last backup
   3. Cumulative incremental since last full backup
   4. Exit the backup program
1 => 1
                                                          In-Use   Block
     Directory                                            Blocks    Size
c:\intersystems\iris1\mgr\fs\                              2,668   (8KB)
c:\intersystems\iris1\mgr\irisaudit\                         102   (8KB)
     Total number of database blocks:                      2,770
Total backup size, including overhead of volume and pass labels:
     For a disk file:
          Number of 512-byte blocks:  46,068  (23,586,816 bytes)
     For magnetic media:
          Number of 58KB blocks:  398  (23,638,016 bytes)


Note 1:^DBSIZE routine is useful for environments that use online backup to back up databases.

Note 2:What is online backup

A method of online backup of used blocks of databases using internal tools of our products (Caché/Ensemble/HealthShare/IRIS).

Another method is to back up the database files online. Please also refer to the FAQ topic "What are the methods for backing up the database?" for differences in backup methods.

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