I am trying to analyze Flash Pool candidacy and optimal cache size for an ONTAP cluster. It is running ONTAP 9.3P13. I followed the instructions on this link.
So far so good, been able to interpret most of its output. But then I tried to see the detailed output using the -t option in the print command. It shows information about the volumes in the aggregate that are the best candidates for being on a Flash Pool aggregate.
Happens that for a specific aggregate, the #1 volume in the list is the following:
Volume #1 VOL_XYZ
Summary of the past 7 intervals
Read Throughput (MB/s): 21.545
Write Throughput (MB/s): 12.757
Cacheable Read (%): 0
Cacheable Write (%): 12
Max Projected Cache Size (GiB): 1.856
Projected Read Hit (%): 50
Projected Write Hit (%): 8
So, could someone explain why and how could this volume have 0% of cacheable reads and even so present a Projected Read Hit of 50%?