| Identified misleading symptom |
Tested TCP connectivity on port 3260 after ping worked; identified port-specific blocking within 10 min |
Checked iSCSI initiator config first, then noticed TCP was blocked |
Spent extended time on iscsid, fstab, or mount troubleshooting |
| Found root cause in datacenter domain |
Traced to inter-VLAN ACL change during hardening; identified missing port 3260 |
Found the ACL was blocking traffic but not the specific change that caused it |
Assumed the storage array was down or the iSCSI target was misconfigured |
| Remediated in networking domain |
Added iSCSI port to ACL, restored mounts on all affected servers, ran missed backups |
Fixed the ACL but only for one server |
Used a workaround (e.g., temporary permit-all rule) |
| Cross-domain thinking |
Explained the tension between security hardening and service availability; proposed storage fabric isolation |
Acknowledged the ACL/iSCSI interaction but missed the hardening project context |
Treated it as a single-domain Linux storage or networking issue |