Data Domain: Disk Has Only One Active Connection Path | MPATH-00005

• System reports an alert indicating only one active connection path (2 are expected)
  • Example: 

  • Event Id: EVT-MPATH-00005
    Event Message: Enclosure 5 Disk 12 only has 1 active connection path and the required number is 2.
    Object: Enclosure=5:Disk=12
    Additional Information: EnclosureSerialNumber=CKM0123456789

• Event ID: EVT-MPATH-00005
• Message: Enclosure <X> Disk <Y> only has 1 active connection path.

The alert is triggered when a disk in a multipath-configured enclosure loses one of its SAS paths.

Possible causes include:

• Disk not properly seated
• SAS connectivity issue
• Improper cabling of expansion shelf
• Faulty disk, carrier, cable, or HBA
• Transient failover/reset of SAS path
• Hotplug issue due to insufficient wait time during disk replacement
• DOA (dead-on-arrival) replacement disk

Step 1: Address Single Disk Alerts.

If the alert relates to a single disk:

1. Run disk rescan from CLI.
2. If onsite, reseat the affected disk. Wait at least 2 minutes between removal and insertion.
3. Tech Support: Power cycle the disk slot using diskpowctl (DS60/ ES40).
4. Disable and reenable the SAS port connected to the affected disk.
5. Replace the disk if the issue persists.

Note: Always observe a 2-minute wait before inserting a replacement disk to avoid hotplug issues.

Step 2: Investigate Disk Health.

Use the following DD-CLI commands and Autosupport data:

• disk show reliability-data
  • Check CRC/RAS counts
• Review Autosupport:
  • Disk Read Error History
  • SMART Data
  • Medium/recovered/other errors

Replace disks showing high, or increasing error counts proactively.

Step 3: Address Enclosure-Wide Alerts

If all disks in an enclosure are affected:

1. Run:

   • alerts show current
   • disk multipath status
   • enclosure show topology
   • enclosure test topology
   • disk port show summary

2. Verify:

   • SAS ports are online
   • Shelves are listed under Connected Enclosure IDs
   • Link speed is correct
   • LCC A and B are present in topology
   • Each disk has two SAS paths (one active, one standby)

If any further assistance is required, raise a Service Request with your contracted Service Provider.

REFERENCE

Some Links may require a customer login:

•  Data Domain Core Documents
• Data Domain Hardware Guides
•  Upload a Support Bundle (SUB)
•  How to run SAS / Shelf Diagnostics
•  Data Domain: Identifying a Defective or Inactive Link Controller Card (LCC)
•  How to power on/off individual disk slots on a DS60 Enclosure
•  Data Domain: SAS Cable Configuration, Topology checks and Testing