The section on
File System Performance Concepts discussed how distributing
I/O load across different disk
drives can improve performance. Further load distribution can be
achieved by separating data and index components of server tables.
To do this, use the DATAPATH= and INDEXPATH= options when configuring
domains.
For example, when performing complex
WHERE clause evaluations, multiple threads are active on index component files and the data
component file at the same time. Splitting the index and data file components into different volumes
can improve performance by reducing disk contention and increasing the level of parallelism
down to the disk-access level.
A word of caution when using DATAPATH= and INDEXPATH= options to distribute the data
and index components: Take extra care when performing and restoring disk backups
of the server tables using a system backup and restore utility. When making a backup,
ensure that the metadata, data, and index component
partition files are of the same generation and are in their respective directories.
When restoring a backup,
restore the component partitions to the same directories where they
were created. To avoid this restore problem, create symbolic links
with the original directory path that point to the restore directories.
Of course, if the components are not separated using the path options,
this restore issue does not apply.
The backup and restore issues are not an issue when using the
SPD Server backup and restore utilities. These utilities resolve any component files when backing
up or restoring tables.
For more information, see Backing Up and Restoring SPD Server Data.