Unable to resize asm datafile even though I resized the (logical) datafile

Question

I have a bigfile that went above 16tb - this is causing me grief in a restore to a netapp filer that has a 16tb limit.
So we went thru the hassles of moving data around. I issued the
Mon Dec 10 21:15:06 2012
alter database datafile '+DATA/pcinf/datafile/users1.303.777062961' resize 15900000000000
Completed: alter database datafile '+DATA/pcinf/datafile/users1.303.777062961' resize 15900000000000
Mon Dec 10 21:40:10 2012
The datafile itself from v$datafile shows 15tb - BUT the asm file is still 18tb in size.
Should it not be the same - is this something others have faced where the asm file doesnt match?
Name     USERS1.303.777062961
Type     DATAFILE
Redundancy     MIRROR
Block Size (Bytes)     8192
Blocks     2281701377
Logical Size (KB)     18253611016
Linux, Exadata, 11.2.0.2 + psu
SR Created but not getting anywhere - Why such a large file, are you sure its really not 18tb, etc .etc
Daryl

Answer 1

So I just ran another test of my real datafile issue and it appears to have corrected itself..
OEM Shows this: (Correct)
Block Size (Bytes)     8192
Blocks     1934814455
Logical Size (KB)     15478515640
select file_id, bytes from dba_data_files where tablespace_name = 'USERS1';
select file#, bytes from v$datafile where file# = (select file_id from dba_data_files where tablespace_name = 'USERS1');
select file#, trunc(bytes/1024/1024/1024) G from v$datafile where file# = (select file_id from dba_data_files where tablespace_name = 'USERS1');
alter database datafile '+DATA/pcinf/datafile/users1.303.777062961' resize 15850000000000;
select file_id, bytes from dba_data_files where tablespace_name = 'USERS1';
select file#, bytes from v$datafile where file# = (select file_id from dba_data_files where tablespace_name = 'USERS1');
select file#, trunc(bytes/1024/1024/1024) G from v$datafile where file# = (select file_id from dba_data_files where tablespace_name = 'USERS1');
   FILE_ID                BYTES
        12   15,900,000,002,048
1 row selected.
     FILE#                BYTES
        12   18,691,697,672,192    <<<< CAUSING ME MUCH MUCH GRIEF!!
1 row selected.
     FILE#          G
        12      17408
1 row selected.
Database altered.
   FILE_ID                BYTES
        12   15,850,000,007,168
1 row selected.
     FILE#                BYTES
        12   15,850,000,007,168
1 row selected.
     FILE#          G
        12      14761
1 row selected.