Detecting free space on flash storage

Storage Subsystem Administration Guide for Hitachi NAS Platform

Version
14.8.x
Audience
anonymous
Part Number
MK-92HNAS012-29

The server performs a regular scan for spans on compressed HDP pools which are in danger of failing because free physical space is very low.

When free space is low, the server can take the following actions:

  • On spans with low space where deleted filesystems exist but vacated chunks do not, the server recycles one or more deleted filesystems.
  • On spans which have vacated chunks, the server launches a process inside the storage that slowly hands space back to the HDP pool and eventually increases physical free space.

To instruct the server to perform the next scan immediately instead of waiting up to three hours for the next scheduled scan, use the following command:

span-expedite-compression-space-check

Note: Use this command sparingly. It is possible that there are HDP pages waiting to be initialised inside the storage and, given time, the system can recover enough free space without taking action.