Mailbox operation fail with error "fmmb.crc.invalid"

Applies to

• MetroCluster
• ONTAP 9.6 and earlier

Issue

During times of high disk utilization e.g. during nightly disk scrubs the below error messages can be observed:

Sat Sep 08 02:17:26 CEST [node-01: fmmbx_diskOpsManager: fmmb.crc.invalid:debug]: params: {'operation': 'Read Opaque', 'side': 'DR Partner', 'diskName': '1b.125L1'}
Sat Sep 08 02:17:26 CEST [node-01: fmmbx_diskOpsManager: fmmb.crc.invalid:debug]: params: {'operation': 'Read Opaque', 'side': 'DR Partner', 'diskName': '1b.125L25'}
Sat Sep 08 02:17:26 CEST [node-01: fmmbx_diskOpsManager: fmmb.crc.invalid:debug]: params: {'operation': 'Read Opaque', 'side': 'DR Partner', 'diskName': '1a.125L8'}
Sat Sep 08 02:17:26 CEST [node-01: fmmbx_diskOpsManager: fmmb.crc.invalid:debug]: params: {'operation': 'Read Opaque', 'side': 'DR Partner', 'diskName': '1a.125L69'}
Sat Sep 08 02:17:29 CEST [node-01: fmmbx_diskOpsManager: fmmb.crc.invalid:debug]: params: {'operation': 'Read Opaque', 'side': 'DR Partner', 'diskName': '1b.125L13'}
Sat Sep 08 02:17:29 CEST [node-01: fmmbx_diskOpsManager: fmmb.crc.invalid:debug]: params: {'operation': 'Read Opaque', 'side': 'DR Partner', 'diskName': '1a.125L7'}
Sat Sep 08 02:17:31 CEST [node-01: DR_config_checker: mcc.config.drPartner.mbxFail:alert]: Read of DR partner's mailbox failed with error (4).