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Data validation can identify data corruption during a client session when data is sent between a client and the server. Tivoli Storage Manager provides the option of specifying whether a cyclic redundancy check (CRC) is performed during a client session to validate data sent over the network between a client or a storage agent and the server.
Cyclic redundancy checking is performed at the client when the client requests services from the server. For example, the client issues a query, backup, or archive request. The server also performs a CRC operation on the data sent by the client and compares its value with the value calculated by the client. If the CRC values do not match, the server will issue an error message once per session. Depending on the operation, the client may attempt to automatically retry the operation.
After Tivoli Storage Manager completes the data validation, the client and server discard the CRC values generated in the current session.
Data validation can be enabled for one or all of the following:
This section provides information about data validation between a node and the server.
See Choosing Where to Enable Data Validation to help you determine where to enable data validation.
Consider the impact on performance when you decide whether data validation is necessary for all nodes or some nodes. Data validation impacts performance because additional CPU overhead is required on both the client and server to calculate and compare CRC values.
This type of validation is independent from validating data written to a storage pool volume. See Data Validation During Audit Volume Processing.
You can enable data validation for a node by using the REGISTER NODE or UPDATE NODE command. By default, data validation is set to NO.
Methods for enabling data validation for a node include choosing data validation for individual nodes, specifying a set of nodes by using a wildcard search string, or specifying a group of nodes in a policy domain.
For example, to enable data validation for existing node, ED, you can issue an UPDATE NODE command. This user backs up the company payroll records weekly and you have decided it is necessary to have all the user data validated: the data itself and metadata.
update node ed validateprotocol=all
Later, the network has shown to be stable and no data corruption has been identified when user ED has processed backups. You can then disable data validation to minimize the performance impact of validating all of ED's data during a client session. For example:
update node ed validateprotocol=no