Question & Answer
Question
What Causes a DMA_ERR to be logged in AIX's errpt?
Sample error details.
LABEL: DMA_ERR IDENTIFIER: 02D12055 Date/Time: Tue Nov 6 15:34:14 2018 Sequence Number: 277275 Machine Id: <Machine_ID> Node Id: <AIX_system_name> Class: S Type: UNKN WPAR: Global Resource Name: VIODMA Description UNDETERMINED ERROR Probable Causes SYSTEM I/O BUS SOFTWARE PROGRAM ADAPTER DEVICE Recommended Actions PERFORM PROBLEM DETERMINATION PROCEDURES Detail Data BUS ID 9000 0340 [...@ ] EVENT CODE 5000 0000 [P... ] LINK REGISTER F100 0000 C011 5E60 [......^` ] SOURCE LOCATION line: 2521 file: d_map_util.c PROBLEM DATA 0000 0000 1000 0067 0000 0000 0000 4000 F100 0A0F 501E 1200 0000 0000 0000 0000 [.......g......@.....P...........] 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 [................................]
Cause
This technote lists some of the most common probable causes.
Answer
Probable Cause #1
The max_xfer_size value of a virtual Fibre Channel adapter was increased from the default value.
Determine if the AIX host has a virtual Fibre Channel adapter configured with a non-default max_xfer_size attribute.
Below is an example of the default value for fcs0:o

If max_xfer_size was increased from the default (0x100000), change the attribute value back to default and monitor the AIX error report.
For more details, see AIX/VIOS Disk and Adapter IO Queue Tuning.
Probable Cause #2
The error was logged for an invalid device.
In the following sample error, details in the PROBLEM DATA make reference to device name, ent5, which was no longer configured on the AIX host. In this scenario, ent5 was an old etherchannel adapter that had been configured and later removed in order to do a live partition mobility.
IDENTIFIER: C258BB1A
Sequence Number: 1467030
Machine Id: <Machine_ID>
Node Id: <AIX_system_name>
Class: S
Type: INFO
WPAR: Global
Resource Name: VIODMA
UNDETERMINED ERROR
SYSTEM I/O BUS
SOFTWARE PROGRAM
ADAPTER
DEVICE
PERFORM PROBLEM DETERMINATION PROCEDURES
BUS ID
9000 0340 [...@ ]
EVENT CODE
1000 0004 [.... ]
LINK REGISTER
0000 0000 0000 0000 [........ ]
SOURCE LOCATION
line: 3035 file: vdev_bus.c
PROBLEM DATA
0000 0000 0000 1801 0000 0000 1000 0008 656E 7435 2E70 6879 706D 656D 0000 0000 [................ent5.phypmem....]
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 [................................]
ent0 Available U9009.42A.786C5E0-V50-C2-T1 Virtual I/O Ethernet Adapter (l-lan) ent1 Available U9009.42A.786C5E0-V50-C4-T1 Virtual I/O Ethernet Adapter (l-lan) ent2 Available U9009.42A.786C5E0-V50-C3-T1 Virtual I/O Ethernet Adapter (l-lan) ent6 Available EtherChannel / IEEE 802.3ad Link Aggregation
Probable Cause #3
Jan 21 20:26:42 VIODMA I DMA_ERR 90000340 20000001 F1000000C011852C [line: 3799 file: vdev_bus.c]
Jan 21 20:26:42 VIODMA I DMA_ERR 90000340 20000000 F1000000C011852C [line: 3757 file: vdev_bus.c]
Jan 21 20:26:42 VIODMA I DMA_ERR 90000340 20000001 F1000000C010774C [line: 3799 file: vdev_bus.c]
Jan 21 20:26:42 VIODMA I DMA_ERR 90000340 20000000 F1000000C010774C [line: 3757 file: vdev_bus.c]
Jan 21 20:26:41 fscsi3 I FCP_ERR10 Unknown error number: 00000401
Jan 21 20:26:41 fscsi3 I FCP_ERR10 Driver is closing with unlogged errors for target port 0x021101
Jan 21 20:04:38 hdisk23 P SC_DISK_ERR7 path 6 path failure; INQUIRY adapter HW failure
...
Jan 21 20:04:37 hdisk1 P SC_DISK_ERR7 path 7 path failure; INQUIRY adapter HW failure
Jan 21 20:03:52 hdisk7 P SC_DISK_ERR7 path 7 path failure; WRITE(10) (04A73600,0008) adapter HW failure
Jan 21 20:03:52 hdisk0 P SC_DISK_ERR7 path 7 path failure; WRITE(10) (27BA31F0,0008) adapter HW failure
Jan 21 20:03:51 hdisk14 P SC_DISK_ERR7 path 6 path failure; WRITE(16) adapter HW failure
Jan 21 20:03:51 hdisk12 P SC_DISK_ERR7 path 14 path failure; WRITE(10) (A7C16800,0040) transport dead
Jan 21 20:03:51 hdisk9 P SC_DISK_ERR7 path 15 path failure; WRITE(16) adapter HW failure
Jan 21 20:03:51 fcs3 I VFC_ERR4 VIOS vios2, vfc_host vfchost67; loc 00F5; Informational message
Jan 21 20:03:51 hdisk3 P SC_DISK_ERR7 path 7 path failure; WRITE(16) adapter HW failure
Jan 21 20:03:51 hdisk2 P SC_DISK_ERR7 path 15 path failure; WRITE(10) (A7DA9240,0040) adapter HW failure
Jan 21 20:03:51 fcs3 I VFC_ERR4 VIOS vios2, vfc_host vfchost67; loc 00F5; Informational message
Jan 21 20:03:51 hdisk13 P SC_DISK_ERR7 path 7 path failure; WRITE(16) adapter HW failure
Jan 21 20:03:51 fcs3 I VFC_ERR4 VIOS vios2, vfc_host vfchost67; loc 00F5; Informational message
Jan 21 20:03:51 fscsi3 P FCP_ERR1 Adapter driver rejected I/O request for port 0x024701; ENOPROTOOPT
Jan 21 20:03:51 fcs3 T VFC_ERR5 VIOS vios2, vfc_host vfchost67; loc 0080; Unexpected error returned from calls to PHYP
The other VFC_ERR4 errors along with the path errors are just the consequence of that preceding error.
Once the ap->state is set to VFC_ERROR, there is no other recovery than to remove (rmdev) and reconfigure the adapter; this appear to have happened at around 20:26 the same day (causing the informational FCP_ERR10 errors to show up).
This problem then leads to invalidating the DMA space being used to exchange data between the client and the server. Hence, the DMA_ERR error on the VIOS when the connection was lost but IO still to be transferred to the client, and the VIODMA DMA_ERR errors on the client on reconfiguration.
Was this topic helpful?
Document Information
Modified date:
20 October 2021
UID
ibm10739749