[Samba] slow directory access, convert_string_internal: Conversion error: Incomplete multibyte sequence

[Gaiseric Vandal]

Mail file is server is a member server is Samba 3.6.26 on Solaris 11.    
It had been a BDC but a few week ago a switched it back to a member 
server.  The 2 current DC's had been running Samba 3.6.25 but switched 
to Samba 4.4.7.  This is  a classic domain.



Some Windows users reported that browsing folders shared from the member 
server have become very slow over the last few weeks. Which may 
correlate to either changing server role on the main file server or 
upgrading the DC's to Samba 4.


I do see this issue intermittently.  I open one file network folder with 
no problems.  I try another, and the progress bar progresses really 
slowly and it may time out.


Some client machine logs shows things like:


           smbd_dirptr_get_entry mask=[*] found
        somedirectory/somedirectory/somefile/@�!�P fname=@�!�P (@�!�P)
        [2016/11/29 18:23:02.279482,  3]
        lib/charcnv.c:537(convert_string_talloc)
           convert_string_talloc: Conversion error: Illegal multibyte
        sequence(�!�P)
        [2016/11/29 18:23:02.279560,  3]
        lib/charcnv.c:528(convert_string_talloc)
           convert_string_talloc: Conversion error: Incomplete multibyte
        sequence(�P)
        [2016/11/29 18:23:02.279628,  3]
        lib/charcnv.c:161(convert_string_internal)
           convert_string_internal: Conversion error: Illegal multibyte
        sequence(�!�P)
        [2016/11/29 18:23:02.279689,  3]
        lib/charcnv.c:140(convert_string_internal)
           convert_string_internal: Conversion error: Incomplete
        multibyte sequence(�P)
        [2016/11/29 18:23:02.279845,  3]
        smbd/dir.c:1049(smbd_dirptr_get_entry)



which may correlate to directories with files with invalid names


I don't seem to see entries correlating to directories I was trying to 
open .

testparm shows

         dos charset = CP850
         unix charset = UTF8


unix and samba data is all in LDAP so consistent idmapping is not a problem.


All shares have

         msdfs root = yes



This problem exists even on shared  volumes that seem to have low disk 
i/o load (using iostat.)



Appreciate any feedback or advice.


Thanks