Flash Cache is stuck in rewarming phase and does not accept insertions
Applies to
ONTAP 9.3P8 and earlier releases
Issue
Flash Cache is stuck in rewarming phase and does not accept insertions with the following symptoms:
- High latency from Disk layer
- High Disk utilization
- Low cache insert/hit rate in Flash Cache
To confirm the low cache insert/hit rate in Flash Cache:
Example:
cluster::> set advanced
Warning: These advanced commands are potentially dangerous; use them only when directed to do so by NetApp personnel.
Do you want to continue? {y|n}: y
cluster::*> statistics start -sample-id <test1> -object ext_cache_obj -counter inserts|hit_percent|rewarm_aggrs_failed
Statistics collection is being started for sample-id: test1
fas8200-2n-dal-1::*> statistics stop -sample-id <test1>
Statistics collection is being stopped for sample-id: test1
fas8200-2n-dal-1::*> statistics show -sample-id <test1>
Object: ext_cache_obj
Instance: ec0
Start-time: 5/18/2021 10:43:17
End-time: 5/18/2021 10:43:25
Elapsed-time: 8s
Scope: cluster-1a
Counter Value
-------------------------------- --------------------------------
hit_percent 0%
inserts 0
Object: ext_cache_obj
Instance: ec0
Start-time: 5/18/2021 10:43:17
End-time: 5/18/2021 10:43:25
Elapsed-time: 8s
Scope: cluster-1b
Counter Value
-------------------------------- --------------------------------
hit_percent 0%
inserts 0
4 entries were displayed.
Notes:
hit_percentshould be 0%, indicating no cache hitsinsertsshould be lower than 10/s, indicating no data is being inserted into Flash Cache