## Technical Restrictions

The following table lists the most important technical restrictions that apply to MaxDB database instances. There can be additional restrictions depending on the operating system that is used.

Technical Restrictions for a Database Instance

Description | Maximum Value
Number of data volumes | 4095 2 (VOLUMENO_BIT_COUNT) -1
Size of a data volume | 512 GB Page size x (2 (32-VOLUMENO_BIT_COUNT) -1)
Number of log volumes | No restrictions
Size of a log volume | 32 TB
Total size of the database instance (data area + log area) | 64 TB

The database system accesses data pages in the data volumes using their converter block address. The converter block address is 32 bits long and consists of the volume number and the offset in the data volume. The larger you set the special database parameter VOLUMENO_BIT_COUNT, the more data volumes you can use. The maximum permitted size of the individual data volumes is reduced accordingly. The following apply: 6 ≤ VOLUMENO_BIT_COUNT ≤ 12 and page size = 8 KB.

The database system handles the log area as a single entity. As a rule, you first configure a log volume. If this log volume is too small, you can either increase the size of this log volume (requires the database instance to be restarted) or insert an additional log volume (this can be done in the ONLINE operational state).

See also:

Creating and Configuring a Database Instance

SQL Reference Manual, Restrictions for SQL Statements