Many System OMF files

Hello,

Oracle 11.2 no updates.

Output from RMAN:

List of Permanent Datafiles

===========================

File Size(MB) Tablespace           RB segs Datafile Name

---- -------- -------------------- ------- ------------------------

1    8192     SYSTEM               ***     /opt/app/oracle/oradata/datafile/o1_mf_system_g2ys1n8h_.dbf

2    2048     SYSAUX               ***     /opt/app/oracle/oradata/datafile/o1_mf_sysaux_g4ys1n8h_.dbf

3    32767    UNDOTBS1             ***     /opt/app/oracle/oradata/datafile/o1_mf_undotbs1_g2ys1n84_.dbf

4    5        USERS                ***     /opt/app/oracle/oradata/datafile/o1_mf_users_g2ys1n8r_.dbf

When I list directory: /opt/app/oracle/oradata/datafile/

I see for each datafile 5 names with different postfix.

Like:

-rw-r-----. 1 oracle oinstall  1688215552 Jan  7  2019 o1_mf_sysaux_g2t9tnbt_.dbf