Zero Downtime Backup of MaxDB database with HP Data Protector

Concept

According to SAP Note 371247, ZDB can be performed on a MaxDB instance if all its data volumes

are split consistently at the same time. It also adds that if this prerequisite cannot be met, there is a

workaround, SAP Note 616814, in which MaxDB’s logwriter must be suspended before the ZDB split

process so that the data volume is made consistent and can then be zero downtime backed up.

In multi-disk environments, it cannot be guaranteed that all volumes are split at the same time. Because this

does not meet the requirements laid down by SAP Note 371247, the only way to perform MaxDB-ZDB is

to suspending the MaxDB’s logwriter before the ZDB split process.

dbmcli –d <database_name> -u <dbm_user>,<password>

#log on to MaxDB CLI

util_connect <dbm_user>,<password> #connect to MaxDB inst

util_execute suspend logwriter

#suspend logwriter

 split mirror/create snapshot

util_execute resume logwriter

#connect to MaxDB inst

util_release #

disconnect from MaxDB

exit

While MaxDB’s logwriter process is suspended, write access to the database is effectively blocked. This

achieves data consistency across the data volumes. However, on large production databases, you should

not suspend the logwriter process for extended periods of time. To avoid this, you can reduce the log-

suspension time significantly by achieving the process of resolution before suspending the logwriter.

Note:

For mirror-based ZDB, it is highly recommended to make the dow

ntime as

small as possible by making sure that the mirrors are in sync before ZDB

commences.

After the split, you can perform any of the three ZDB variants: disk, tape, or disk+tape. The following apply:

 The ZDB backup will be a plain file-system backup and so MaxDB will not be aware of the backup.

As a consequence, such backups will not show up in MaxDB’s backup history.

 Being a file-level backup, this approach typically requires more tape space than database

block-level backups.

The following outlines the process of MaxDB-DP Zero Downtime Backup. During the ZDB the following

actions take place:

 The ZDB Agent is started

 Resolution of datafiles to be backed up

 MaxDB’s Logwriter is suspended

 The array splits MaxDB’s data volume, which is consistent

 MaxDB’s Logwriter is resumed

 The Backup host and ZDB Media Agent are prepared for local backup

 The Disk agent backs up the snapshot