diff --git a/mediachanger/castorrmc/rmc/rmc_unmnt.c b/mediachanger/castorrmc/rmc/rmc_unmnt.c
new file mode 100644
index 0000000000000000000000000000000000000000..7e7d869f00823c122b526023ec0d4402ab0b2070
--- /dev/null
+++ b/mediachanger/castorrmc/rmc/rmc_unmnt.c
@@ -0,0 +1,92 @@
+/******************************************************************************
+ * rmc/rmc_unmnt.c
+ *
+ * This file is part of the Castor project.
+ * See http://castor.web.cern.ch/castor
+ *
+ * Copyright (C) 2003 CERN
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ *
+ *
+ * @author Steven.Murray@cern.ch
+ *****************************************************************************/
+
+/* rmc_unmnt - unmount a cartridge from a drive that maybe in either */
+/* a SCSI compatible or an ACS compatible tape library */
+
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <netinet/in.h>
+#include "h/marshall.h"
+#include "h/rmc_api.h"
+#include "h/rmc_constants.h"
+#include "h/serrno.h"
+
+#include <errno.h>
+#include <string.h>
+
+int rmc_unmnt(
+ const char *const server,
+ const char *const vid,
+ const char *const loader)
+{
+ const gid_t gid = getgid();
+ const uid_t uid = getuid();
+
+ /* The total length of the fixed size members of the request message */
+ /* is Magic (4 bytes) + request ID (4 bytes) + length (4 bytes) + */
+ /* uid (4 bytes) + gid (4 bytes) = 20 bytes */
+ const int msglen = 20 + strlen(vid) + 1 + strlen(loader) + 1;
+
+ char repbuf[1];
+ char *sbp = NULL;
+ char sendbuf[RMC_REQBUFSZ];
+
+ /* Consider the function arguments invalid if the total size of the */
+ /* request message would be greater than RMC_REQBUFSZ */
+ if(msglen > RMC_REQBUFSZ) {
+ errno = ERMCUNREC;
+ serrno = errno;
+ return -1;
+ }
+
+ if(CA_MAXVIDLEN < strlen(vid)) {
+ errno = ERMCUNREC;
+ serrno = errno;
+ return -1;
+ }
+
+ /* Build request header */
+ sbp = sendbuf;
+ marshall_LONG (sbp, RMC_MAGIC);
+ marshall_LONG (sbp, RMC_GENERICUNMOUNT);
+ marshall_LONG (sbp, msglen);
+
+ /* Build request body */
+ marshall_LONG (sbp, uid);
+ marshall_LONG (sbp, gid);
+ marshall_STRING (sbp, vid);
+ marshall_STRING (sbp, loader);
+
+ /* Being paranoid; checking the calculated message length against */
+ /* the number of bytes marshalled */
+ if(sbp - sendbuf != msglen) {
+ errno = SEINTERNAL;
+ serrno = errno;
+ return -1;
+ }
+
+ return send2rmc (server, sendbuf, msglen, repbuf, sizeof(repbuf));
+}
diff --git a/mediachanger/castorrmc/rmc/rmc_unmnt.man b/mediachanger/castorrmc/rmc/rmc_unmnt.man
new file mode 100644
index 0000000000000000000000000000000000000000..c33dc3b199862243680d45c1a2f15e851c05507c
--- /dev/null
+++ b/mediachanger/castorrmc/rmc/rmc_unmnt.man
@@ -0,0 +1,66 @@
+.\" Copyright (C) 2002 by CERN/IT/PDP/DM
+.\" All rights reserved
+.\"
+.TH RMC_UNMNT 3 "$Date: 2013/11/18 16:21:00 $" CASTOR "rmc Library Functions"
+.SH NAME
+rmc_unmnt \- send a request to the Remote Media Changer daemon to have a volume unmounted
+.SH SYNOPSIS
+.B #include <sys/types.h>
+.br
+\fB#include "rmc_api.h"\fR
+.sp
+.BI "int rmc_unmnt (char *" server ,
+.BI "char *" vid ,
+.BI "char *" loader );
+.SH DESCRIPTION
+.B rmc_unmnt
+asks the Remote Media Changer server running on
+.I server
+to unmount the volume
+.I vid
+from the drive specified by
+.IR loader .
+.TP
+.I server
+specifies the Remote Media Changer to be contacted.
+.TP
+.I vid
+is the volume visual identifier.
+It must be at most six characters long.
+.TP
+.I loader
+specifies the drive in the robot in one of the following forms:
+.RS
+.TP
+acsACS_NUMBER,LSM_NUMBER,PANEL_NUMBER,TRANSPORT_NUMBER
+.TP
+manual
+.TP
+smc@hostname,drive_ordinal
+.RE
+
+.LP
+This function requires TP_SYSTEM privilege in the Cupv database.
+.SH RETURN VALUE
+This routine returns 0 if the operation was successful or -1 if the operation
+failed. In the latter case,
+.B serrno
+is set appropriately.
+.SH ERRORS
+.TP 1.2i
+.B SECOMERR
+Communication error.
+.TP
+.B ERMCUNREC
+Unknown host or invalid loader or vid too long or requester does not have
+TP_SYSTEM privilege in the Cupv database.
+.TP
+.B ERMCFASTR
+Unit attention.
+.TP
+.B ERMCOMSGR
+Hardware error or Medium Removal Prevented.
+.SH SEE ALSO
+.BR Cupvlist(1) ,
+.SH AUTHOR
+\fBCASTOR\fP Team <castor.support@cern.ch>