Performing large file system expansions

Storage Subsystem Administration Guide for Hitachi NAS Platform

Part Number

Large file system expansions should not be performed when the system is heavily loaded.

Note: The following warning against large expansions applies only when you have not used span-hdp-preallocation to disable pre-alloc writes.
The system is heavily loaded when:
  • experiencing heavy I/O load, especially write load
  • rebuilding a parity group or pool volume after a disk failure
  • formatting new disk space
  • zero-initializing space after recent use of the span-unmap-vacated-chunks command.

Therefore, if a large expansion is requested, the filesystem-expand command prompts you to supply the --storage-is-lightly-loaded switch and will not proceed without it.