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Multiple errors with identifier B0EE9AF5 logged on AIX or VIO server

Question & Answer


Question

AIX server is reporting recurring errors with identifier B0EE9AF5 associated with MPIO hdisk devices. What is the root cause?
errpt | more
IDENTIFIER TIMESTAMP  T C RESOURCE_NAME  DESCRIPTION
B0EE9AF5   0305153125 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305153025 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305152925 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305152825 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305152725 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305152625 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305152525 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED
B0EE9AF5   0305152425 T S hdisk#         REQUESTED OPERATION CANNOT BE PERFORMED

Cause


Error B0EE9AF5 indicate a reservation conflict on a path to an MPIO hdisk device.
Reservation conflicts typically occur in environments where multiple initiators (e.g., AIX hosts, Fibre Channel adapter ports, or processes) attempt to access or open a shared disk concurrently.

If an initiator places a reservation on a disk, it restricts access to other initiators, resulting in operational errors.
This scenario is common in clustered environments like HACMP or GPFS, where shared disk access is routine.
Common Causes

1. SCSI-2 Reservation or Reserve Policy Misconfiguration

If SCSI reservation methodology is employed when the MPIO device is opened, this can lead to reservation conflict.
The SCSI-2 reservation policy locks the device to a single initiator (path), and commands routed through any other path result in a reservation conflict.
The reserve_policy attribute determines the reservation behavior:
  • single_path: Reserves the disk for one path, potentially causing conflicts in shared environments.
  • no_reserve: Allows concurrent access, reducing conflicts.
For more information, see MPIO device attributes.
 

2. Stale Reservation

A stale reservation on the storage or an incorrect reserve_lock / reserve_policy may be left in the kernel.
Even with no_reserve configured, stale reservations may persist if a process or initiator does not correctly release the disk.

3. Missing Storage Fileset(HAK)
Storage Host Attachment Kit (HAK) for AIX is a software pack that simplifies the task of connecting an IBM AIX host to a storage system.
The HAK provides a set of command-line interface tools that help host administrators perform different host-side tasks, such as: detect any physically
connected storage system (single system or multiple systems), detect storage volumes, define the host on the storage system, run diagnostics, and apply best
practice native multi-path connectivity configuration on the host.
When non-IBM storage is presented to AIX without the vendor’s Host Attachment Kit (HAK), AIX defaults to single_path reservation.
This can lead to conflicts unless the correct ODM storage definitions are installed.

Answer


To check and release the reservation on a disk, use the following approach:
1. Ensure the storage HAK is installed on the AIX server. 
Contact your vendor storage support to supply you with the appropriate storage HAK.
2.  Use lsattr -El hdisk# -a reserve_policy to verify the current reserve policy. 
If the disk is shared between multiple initiators, set the policy to no_reserve as recommended in IBM AIX MPIO Best Practices and Considerations.
3. If the reserve_policy is set to no_reserve and the problem persist, use devrsrv command to identify and clear the stale reservation.
Need Further Assistance?
If the above steps do not resolve the issue, open a case with IBM Support.
Please be sure to collect a snap from the affected AIX server and upload it to your case as instructed here.
 

Recommended Documentation:

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Document Information

Modified date:
14 April 2025

UID

ibm17230790

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