Estimating size of nzbackup data

Answer

The nzbackup command has an undocumented option that estimates the amount of data the operation will back up, regardless of whether the output will be directed to the filesystem or to tape (Veritas). The option is available on systems running NPS 4.0 or later, although calculating the output differs with releases 6.0 and later. This article describes the process for NPS releases prior to 6.0, Netezza 6.0, and Netezza 6.0.2 and later.

To get this estimate in any release later than NPS 4.0, add the -dropdata and -v options to the nzbackup command line. Note that when you use the -dropdata option, NPS does not write any data to disk. Specify a dummy filesystem, such as /tmp. For example: 

[nz@box2 ~]$ nzbackup -db XYZ -dir /tmp -dropdata  -v
[Backup Server] : Starting the backup process
[Backup Server] : Backing up functions
[Backup Server] : Backing up aggregates
[Backup Server] : Start retrieving the schema
[Backup Server] : Backing up to /tmp/Netezza/cs-spubox2/XYZ/20090820150730/1/FULL
[Backup Server] : Retrieving user information
[Backup Server] : Backing up sequences
[Backup Server] : Backing up table schema.
[Backup Server] : Backing up External Tables.
[Backup Server] : Backing up External table settings.
[Backup Server] : Backing up Table Constraints
[Backup Server] : Backing up synonyms
[Backup Server] : Backing up stored procedures
[Backup Server] : Backing up materialized views
[Backup Server] : Backing up view definitions.
[Backup Server] : Retrieving group information
[Backup Server] : Retrieving group members
[Backup Server] : Backing up ACL information
[Backup Server] : Start retrieving the data.
[Backup Server] : Backing up table CLOSING_PRICES
[Backup Server] : Backing up table DAILY_TRADE_PRICES
[Backup Server] : Backing up table EQT_INSTRUMENT_TRADE_TRENDS
[Backup Server] : Backing up table EQUITY
[Backup Server] : Backing up table EXECUTIONS
[Backup Server] : Backing up table ORDERS
[Backup Server] : Backing up table QUOTES
[Backup Server] : Backing up table SMD_MKTCAP
[Backup Server] : Backing up table TICKDATA_QUOTES
[Backup Server] : Backing up table TRADES
[Backup Server] : severity=3 source=3 errCode=0 otherErrCode=0 : Number of bytes dropped (-dropData) : 31789
[Backup Server] : Operation committed
Backup of database XYZ to backupset 20090820150730 completed successfully.

Calculating Backup Size

Find the correct release in the descriptions below.

Releases NPS 4.0 and prior to 6.0

The highlighted line, in the example above, indicates how many bytes of data nzbackup will be backing up:

Number of bytes dropped (-dropData) : 31789

Release 6.0

Beginning with IBM Netezza 6.0, the backup and restore process provides multistream support. As a result, each stream has its own instance of the data server (bnrdatasvr) process and accompanying log file. You must perform some additional calculations after executing the command shown in the example

To learn the total estimated backup size, add the -dropData value shown in the bnrdatasvr log file associated with each stream, as well as the main backupsvr log file. These files are typically located in subdirectories of /nz/kit/log, and named in the format bnrdatasvr.<pid>.<date> and backupsvr.<pid>.<date>.log.

Release 6.0.2 and later

With the release of IBM Netezza 6.0.2, all -dropData values are written to the main backupsvr log file. To calculate the total estimated backup size, find each value listed in backupsvr.<pid>.<date>.log and add them together. The file is typically located in the backupsvr subdirectory of /nz/kit/log.