Troubleshooting

DAOS Errors

DAOS error numbering starts at 1000. The most common errors are documented in the table below.

DAOS Error	Value	Description
DER_NO_PERM	1001	No permission
DER_NO_HDL	1002	Invalid handle
DER_INVAL	1003	Invalid parameters
DER_NOSPACE	1007	No space left on storage target
DER_NOSYS	1010	Function not implemented
DER_IO	2001	Generic I/O error
DER_ENOENT	2003	Entry not found
DER_KEY2BIG	2012	Key is too large
DER_IO_INVAL	2014	IO buffers can't match object extents

When an operation fails, DAOS returns a negative DER error. For a full list of errors, please check https://github.com/daos-stack/cart/blob/master/src/include/gurt/errno.h (DER_ERR_GURT_BASE is equal to 1000 and DER_ERR_DAOS_BASE is equal to 2000).

The function d_errstr() is provided in the API to convert an error number to an error message.

Debugging System

DAOS uses the debug system defined in CaRT but more specifically the GURT library. Log files for both client and server are written to "/tmp/daos.log" unless otherwise set by D_LOG_FILE.

Registered Subsystems/Facilities

The debug logging system includes a series of subsystems or facilities which define groups for related log messages (defined per source file). There are common facilities which are defined in GURT, as well as other facilities that can be defined on a per-project basis (such as those for CaRT and DAOS). DD_SUBSYS can be used to set which subsystems to enable logging. By default all subsystems are enabled ("DD_SUBSYS=all").

• DAOS Facilities: common, tree, vos, client, server, rdb, pool, container, object, placement, rebuild, tier, mgmt, bio, tests

• Common Facilities (GURT): MISC, MEM

• CaRT Facilities: RPC, BULK, CORPC, GRP, LM, HG, ST, IV

Priority Logging

All macros that output logs have a priority level, shown in descending order below.

• D_FATAL(fmt, ...) FATAL

• D_CRIT(fmt, ...) CRIT

• D_ERROR(fmt, ...) ERR

• D_WARN(fmt, ...) WARN

• D_NOTE(fmt, ...) NOTE

• D_INFO(fmt, ...) INFO

• D_DEBUG(mask, fmt, ...) DEBUG

The priority level that outputs to stderr is set with DD_STDERR. By default in DAOS (specific to the project), this is set to CRIT ("DD_STDERR=CRIT") meaning that all CRIT and more severe log messages will dump to stderr. However, this is separate from the priority of logging to "/tmp/daos.log". The priority level of logging can be set with D_LOG_MASK, which by default is set to INFO ("D_LOG_MASK=INFO"), which will result in all messages excluding DEBUG messages being logged. D_LOG_MASK can also be used to specify the level of logging on a per-subsystem basis as well ("D_LOG_MASK=DEBUG,MEM=ERR").

Debug Masks/Streams:

DEBUG messages account for a majority of the log messages, and finer-granularity might be desired. Mask bits are set as the first argument passed in D_DEBUG(mask, ...). To accomplish this, DD_MASK can be set to enable different debug streams. Similar to facilities, there are common debug streams defined in GURT, as well as other streams that can be defined on a per-project basis (CaRT and DAOS). All debug streams are enabled by default ("DD_MASK=all").

• DAOS Debug Masks:

  • md = metadata operations

  • pl = placement operations

  • mgmt = pool management

  • epc = epoch system

  • df = durable format

  • rebuild = rebuild process

  • daos_default = (group mask) io, md, pl, and rebuild operations

• Common Debug Masks (GURT):

  • any = generic messages, no classification

  • trace = function trace, tree/hash/lru operations

  • mem = memory operations

  • net = network operations

  • io = object I/Otest = test programs

Common Use Cases

• Generic setup for all messages (default settings)

  $ D_LOG_MASK=DEBUG
  $ DD_SUBSYS=all
  $ DD_MASK=all
  

• Disable all logs for performance tuning

  $ D_LOG_MASK=ERR -> will only log error messages from all facilities
  $ D_LOG_MASK=FATAL -> will only log system fatal messages
  

• Disable a noisy debug logging subsystem

  $ D_LOG_MASK=DEBUG,MEM=ERR -> disables MEM facility by 
  restricting all logs from that facility to ERROR or higher priority only
  

• Enable a subset of facilities of interest

  $ DD_SUBSYS=rpc,tests
  $ D_LOG_MASK=DEBUG -> required to see logs for RPC and TESTS
  less severe than INFO (the majority of log messages)
  

• Fine-tune the debug messages by setting a debug mask

  $ D_LOG_MASK=DEBUG
  $ DD_MASK=mgmt -> only logs DEBUG messages related to pool
  management
  

Refer to the DAOS Environment Variables document for more information about the debug system environment.

Common DAOS Problems

This section to be updated in a future revision.

Bug Report

Bugs should be reported through our issue tracker^1 with a test case to reproduce the issue (when applicable) and debug logs.