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Bob,

I ran with 256KB blocksize on Win2K with 9840A/B and 9940B for years, and
did many many restores with no problems.

As others say, it probably depends on the HBA driver. I think we had Emulex
LP8000.

But the number one rule is - after you've changed the blocksize, thoroughly
test that you can still restore - from backups written both before and afte=
r
the change.

Regards,
Dean

On 11/17/05, Bob Stump <stumpb AT michigan DOT gov> wrote:
>
> 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 specifie=
d
> 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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Bob,<br>
<br>
I ran with 256KB blocksize on Win2K with 9840A/B and 9940B for years, and d=
id many many restores with no problems.<br>
<br>
As others say, it probably depends on the HBA driver. I think we had Emulex=
 LP8000.<br>
<br>
But the number one rule is - after you've changed the blocksize,
thoroughly test that you can still restore - from backups written both
before and after the change.<br>
<br>
Regards,<br>
Dean<br><br><div><span class=3D"gmail_quote">On 11/17/05, <b class=3D"gmail=
_sendername">Bob Stump</b> &lt;<a href=3D"mailto:stumpb AT michigan DOT 
gov">stump=
b AT michigan DOT gov</a>&gt; wrote:</span><blockquote class=3D"gmail_quote" 
style=
=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; p=
adding-left: 1ex;">
Thank ypu to all who answered my earlier post.<br>The correct answer given =
to me was&nbsp;&nbsp;256K (262144)<br><br>Here is a followup question.<br>C=
an this value also be used in W2K and W2K3 servers?<br>I seem to remember l=
imitations in earlier versions of Windows/NetBackup.
<br><br><br>&gt;&gt;&gt; Bob Stump 11/15/2005 4:47 PM &gt;&gt;&gt;<br>Becau=
se
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.<br=
><br>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.<br><br>What is the optimum for STK 9940B?<br><br>=
<br>_______________________________________________<br>Veritas-bu maillist&=
nbsp;&nbsp;-&nbsp;&nbsp;<a href=3D"mailto:Veritas-bu AT mailman.eng.auburn DOT 
edu=
">Veritas-bu AT mailman.eng.auburn DOT edu
</a><br><a href=3D"http://mailman.eng.auburn.edu/mailman/listinfo/veritas-b=
u">http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu</a><br></block=
quote></div><br>

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