AWR report- what does this metric mean ?

I have a SR opened with Oracle, but I am struggling to determine what this 
metric in AWR means-

Av Buf Wt(ms)  - I cannot tell if this means Average Buffer Wait(ms), or 
Average Buffer Write(ms).  In the 
Context of the earlier  "Av Rd(ms)" it makes me think that its Average Buffer 
Write, but how can I get such a 
Wide range between reads and writes?  This is on a very high end NetApp san 
storage.  The AWR report for disk i/o does not match the SAN statistics at all- 
we get sub-5 ms i/o's reported on the SAN side, but on the OS side I do see 
some above average times under i/o stat, but still sub-15ms times when it gets 
ugly.

Tablespace IO Stats               DB/Inst: xxxx/xxxxxx  Snaps: 26941-26987
-> ordered by IOs (Reads + Writes) desc          
 
Tablespace   
------------------------------
                 Av      Av     Av                       Av     Buffer Av Buf
         Reads Reads/s Rd(ms) Blks/Rd       Writes Writes/s      Waits Wt(ms)
-------------- ------- ------ ------- ------------ -------- ---------- ------
XXXDAT01
       143,639       3    2.9     1.7      985,708       24     26,753   43.5
XXXDX01
        13,492       0    4.2     1.0      946,883       23        708  145.5
UNDOTBS6
        61,740       1    3.8     1.0       51,146        1      1,079    3.0
XXXLOB01
        47,916       1    6.1     1.0       37,402        1     13,511    4.8
SYSAUX
         5,221       0    2.6     1.0       20,370        0          0    0.0


Some parameters that might influence this-

db_block_checking             MEDIUM
db_block_checksum             TYPICAL
db_block_size                 8192

db_lost_write_protect         TYPICAL

This is 11gR1 RAC to a Dataguard 11gR1 RAC setup, x64 RedHat Linux 5
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