You now can specify "hours" for the Units attribute value, and as such the I/O stats collection PERIOD can be much shorter than in previous releases. When not using solid state disks (SSDs), you can only specify "days" for the Units attribute value, which might be sufficient for your needs. However, a PERIOD shorter than a day is required in the context of using SSDs since the candidate files and their activity levels can change during the day. As a result, SmartTier must scan more frequently, which leads to a higher scan load on the host systems.
Scan frequently, such as every few hours. Frequent scans potentially reduce the number of inodes that VxFS touches and logs in the File Change Log (FCL) file, thereby limiting the duration of each scan. As such, the changes that VxFS collects in the FCL file since the last scan provide details on fewer active files.