Before defragmenting, review the conditions related to defragmentation during a heavy storage system load, when Thin Image pair operations are in progress, when the storage system is powered on or off, and when the defrag process is stopped.
Defrag processing during a heavy system load
If the load placed on the storage system becomes high, the defrag processing automatically pauses to suppress the influence on the host server’s I/O performance. When the load becomes low, the defrag processing resumes. The defrag processing pauses when either of the following conditions exist:
- MP usage rate. The usage rate of the owner MP unit for the root volume being defragged is 50% or higher.
- Write pending rate. The write pending rate of the CLPR to which the root volume being defragged belongs is 30% or higher.
Defrag processing and Thin Image pair operations
- The Thin Image pair operations in the snapshot tree that are being defragged are available even during the defrag processing, but the defrag processing pauses if a pair is resynchronized, restored, or deleted. Also, the defrag processing pauses when cloning is completed. The defrag operation resumes when the pair operation finishes. After a paused defrag process resumes, the progress of the defrag processing returns to 0%.
- If you start defrag processing while a pair operation is underway for the snapshot tree to be defragged, the defrag processing starts after the pair operation finishes.
Defrag processing and powering on or off the storage system
If the storage system power is turned off, the defrag processing pauses. When the power is turned on, the defrag processing resumes.
Stopping the defrag processing
If either of the following operations is performed during the defrag processing, the storage system stops the defrag processing:
- All pairs are deleted in the snapshot tree to be defragged.
- The local replication is initialized.