Good afternoon;
   Can anyone tell me -- or point me toward a source for -- the tape I/O size 
for an SDLT 220 drive (in a Sun L25 )?
   I was looking into tuning the buffers on one of my Media Servers, and I 
found a Veritas article (http://seer.support.veritas.com/docs/183702.htm) which 
states, "IMPORTANT:  Because the data buffer size equals the tape I/O size, the 
value specified in SIZE_DATA_BUFFERS must not exceed the maximum tape I/O size 
supported by the tape drive or operating system. This is usually 256K or 128K 
bytes."
   But it also says, "NOTE: For Digital Linear Tape (DLT) drives the number 
that seems to give the best performance for SIZE_DATA_BUFFERS is 65536." Which 
is fine for old DLT drives, but hwat about Super DLT?
   I've been running with SIZE_DATA_BUFFERS set to 65536 on both of my Media 
Servers, and I get a _lot_ of "waiting for full buffer" messages on one of 
them(NBU 3.4, Solaris 8 on a V120 with the one-SDLT 220 L25 library). Worse, 
the raw throughput figures for this server are consistantly lower than my other 
Media Server (a Sun 420R, Solais 2.6, driving one Quantum DLT8000 drive in a 
Sun L9 library).
   I can't find this on Sun's site, however, and I certainly don't know it off 
the top of my head. Any pointers are much appreciated.
-wde
P.S Could the performance gap be because the 420 has four CPUs and the V120 
just one? The 420 also acts as an Oracle application server, and the V120 is 
only an NBU server.
--
Will Enestvedt
UNIX System Administrator
Johnson & Wales University -- Providence, RI