Veritas™ Volume Manager Administrator's Guide

Combining mirroring and striping

When you have multiple I/O streams, you can use mirroring and striping together to significantly improve performance.

Because parallel I/O streams can operate concurrently on separate devices, striping provides better throughput. When I/O fits exactly across all stripe units in one stripe, serial access is optimized.

Because mirroring is generally used to protect against loss of data due to disk failures, it is often applied to write-intensive workloads. This approach degrades throughput. In those cases, you can combine mirroring with striping to deliver high availability and increased throughput.

You can create a mirrored-stripe volume. Stripe half of the available disks to form one striped data plex, and stripe the remaining disks to form the other striped data plex in the mirror. This approach is often the best way to configure a set of disks for optimal performance with reasonable reliability. However, if a disk in one of the plexes fails, the entire plex is unavailable.

You can also arrange equal numbers of disks into separate mirror volumes. Afterwards, create a striped plex across these mirror volumes to form a striped-mirror volume.

If a disk in a mirror fails, it does not take the disks in the other mirrors out of use. For large volumes or large numbers of disks, a striped-mirror layout is preferred over a mirrored-stripe layout.