ORA-29283: invalid file operation

Today I 've got the following problem: the procedure, which was planned to write a file through UTL_FILE to a mounted resource, is unable to do so despite the proper privileges on the directory. At the same time the local OS user (db owner) was able to do it without problem. The whole thing was done on an AIX OS, and the mounted resource was presented through NFS - in general many points of problems.

The investigation

Running a test procedure produced something like:

ORA-29283: invalid file operation
ORA-06512: at "SYS.UTL_FILE", line 536
ORA-29283: invalid file operation
ORA-06512: at "TCCS.TEST_UTL_FILE", line 6
ORA-06512: at line 1
29283. 00000 -  "invalid file operation"
*Cause:    An attempt was made to read from a file or directory that does
           not exist, or file or directory access was denied by the
           operating system.
*Action:   Verify file and directory access privileges on the file system,
           and if reading, verify that the file exists.

The truss on the db process while calling the test procedure

kread(16, "\0\v\0\0\f\0\0\001\002 i".., 8208) (sleeping...)
kread(16, "\0 _\0\006\0\0\0\0\011 i".., 8208)   = 95
statx("/home/tccs/files/out/utlout.txt", 0x0FFFFFFFFFFE9140, 176, 010) Err#13 EACCES
statfs("/home/tccs/files/out/utlout.txt", 0x0FFFFFFFFFFE8D20) Err#13 EACCES
statx("/home/tccs/files/out/utlout.txt", 0x0FFFFFFFFFFE8FF8, 176, 011) Err#13 EACCES
kopen("/home/tccs/files/out/utlout.txt", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH) Err#13 EACCES
kwrite(16, "\0\v\0\0\f\0\0\001\001", 11)        = 11
kwrite(16, "\0\v\0\0\f\0\0\001\002", 11)        = 11
kread(16, "\0\v\0\0\f\0\0\001\002 i".., 8208)   = 11
lseek(5, 701440, 0)                             = 701440
kread(5, "\00F r V\0\0\0 b r W\0\0".., 512)     = 512
lseek(5, 162304, 0)                             = 162304
kread(5, "\0\n19 n\0\0\0 D19 o\0\0".., 512)     = 512
lseek(5, 701440, 0)                             = 701440
kread(5, "\00F r V\0\0\0 b r W\0\0".., 512)     = 512
lseek(5, 162304, 0)                             = 162304
kread(5, "\0\n19 n\0\0\0 D19 o\0\0".., 512)     = 512
kwrite(16, "\0 �\0\006\0\0\0\0\00401".., 233)   = 233
kread(16, "\0\v\0\0\f\0\0\001\002 i".., 8208) (sleeping...)

The 1st investigation point was brought by the article at http://jakub.wartak.pl/blog/?p=272. But after a while it become clear that, though the conditions were met and we changed the ownership of the mount point, the problem has persisted.
The 2nd guess was by suggestion in the article on MOS:Session Accessing File On Disk Fail with OS File Permission Errors (Doc ID 392647.1). And simple check that the local user connected on BEQUEATH is able to run such procedure without problem proofed that this is the right way - after the listener restart the remote users also acquired the ability to run procedure without problems. The root cause was that the db owner was added to the group being the owner of the target directory long after the listener was started - hence the remote sessions did not acquire the proper permissions on the directory, while the local sessions with "fresh" permissions worked ok.