I have move from NFS to ISCSI and now the situation in much better:
Thu Sep 26 08:00:36 CEST 2019
======== AUDIT ===========
Successful: 43 (31)
Recoverable failed: 0 (1)
Unrecoverable failed: 0 (0)
Success Rate Min: 100.0% (96.875%)
Success Rate Max: 100.0% (100.0%)
======== DOWNLOAD ========
Successful: 9875 (1873)
Failed: 54 (1)
Success Rate: 99.4561385839% (99.946638207%)
======== UPLOAD ==========
Successful: 3111 (570)
Rejected: 0 (2355)
Failed: 70 (195)
Acceptance Rate: 100.0% (19.4871794872%)
Success Rate: 97.7994341402% (74.5098039216%)
======== REPAIR DOWNLOAD =
Successful: 0 (0)
Failed: 0 (0)
Success Rate: 0% (0%)
======== REPAIR UPLOAD ===
Successful: 0 (0)
Failed: 0 (0)
Success Rate: 0% (0%)
Can I try to increase the storage2.max-concurrent-request ?