I couldn't get anything larger than 64K on my Win2k3 server.

http://seer.support.veritas.com/docs/244652.htm
http://seer.support.veritas.com/docs/278837.htm

http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q152518&;


The limitation of 64K you're running into is not a hardware limitation,
nor a NetBackup limitation.  It's a OS/Driver limitation.  The default
maximum blocksize Windows allows is 64K blocksize.  If there is a way to
increase this limitation for your hardware via drivers you must check
with your hardware vendor.  The driver support for > 64K must be
implemented for both the tape drives as well as the HBA as mentioned in
the technote document.


Snip from log when trying to use 256K blocksize----
12:23:45.688 [1068.3228] <16> io_open: The tape device at index -1 has a 
maximum block size of 32768 bytes, a buffer size of 262144 cannot be used
12:23:45.688 [1068.3228] <2> get_tape_path: drive index 0, DOS name:\\. \Tape0, 
PnP name: 
\\?\scsi#sequential&ven_hp&prod_ultrium_2-scsi&rev_f43w#6&178c1b9f&0&050#{53f5630b-b6bf-11d0-94f2-00a0c91efb8b}
12:23:45.698 [1068.3228] <2> check_serial_no: serial number match for drive 
\\.\Tape0, drive index 0, drive serial number HUL4K02472, expected serial 
number HUL4K02472
---Snip

-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Spearman,
David
Sent: Wednesday, November 16, 2005 11:13 AM
To: Paul Keating; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] limitations on SIZE_DATA_BUFFERS


W2K3 can utilize 256 buffers, however we have w2k,w2k3,and various
flavors of unix and have opted for 64K throughout the enterprise,
including the master and media servers.

David Spearman
County of Henrico, Va.

-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of Paul
Keating
Sent: Wednesday, November 16, 2005 11:08 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] limitations on SIZE_DATA_BUFFERS


If I remember correctly, that windows limitation was on network buffer
size, not the tape buffer

??

I could be wrong.

Paul

> -----Original Message-----
> From: veritas-bu-admin AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of 
> Bob Stump
> Sent: November 16, 2005 10:56 AM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] limitations on SIZE_DATA_BUFFERS
> 
> 
> Thank ypu to all who answered my earlier post.
> The correct answer given to me was  256K (262144)
> 
> Here is a followup question.
> Can this value also be used in W2K and W2K3 servers?
> I seem to remember limitations in earlier versions of
> Windows/NetBackup.
> 
> 
> >>> Bob Stump 11/15/2005 4:47 PM >>>
> 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 256 KB or 128 KB.
> 
> For Digital Linear Tape (DLT) drives, the number that seems
> to give the best performance for SIZE_DATA_BUFFERS is 65536. 
> Further performance improvements can be achieved by 
> increasing the value in the NUMBER_DATA_BUFFERS file.
> 
> What is the optimum for STK 9940B?
> 
> 
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu 
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> 

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