Re: [Networker] [NetWorker] setting block size

Hi Teresa

I've read the whole thread that followed your initial posting.  The only
additional (and, I hope useful) thought I have is to mention that idea of
'levels'.

An often-used concept in networks is the idea of 'levels', where the most
basic communication is done at the lowest layer (the 'physical' layer);
riding on top of the physical layer are the six other network layers, each
building on what has been provided by the lower levels.  It's useful to
think of a network design as a seven-layer cake.

Let's try the cake analogy to your problem.  There are many layers to this
block size issue.  At the top of the cake is NetWorker.  Legato has, through
testing, determined the optimal block size for each output device it
supports.  These optimal block size values are provided in a table that is
present in every NetWorker storage node system.  The same block size values
are used in this NetWorker table no matter what operating system NetWorker
is running on.  For instance, the NetWorker optimal block size value for the
DLT 7000 is 128 KB.  So, whether you write to a DLT 7000 using NetWorker
running on Windows 2000, Linux, Solaris, HP-UX or any other
NetWorker-supported platform, NetWorker will always format the output data
in 128 KB chunks.

But NetWorker does not write to the output device directly; here is where
the other layers in the cake come in.  I can't quote all the levels, but the
data-to-be-written will pass from NetWorker down through one or more file
system drivers [not used for tape devices], operating system drivers, host
bus adapter drivers (I know I'm missing some) until the data is actually
delivered to the output device.  Any one of these other levels could have
its own maximum block size that would limit the block size written.  I
believe that is what you are seeing; something other than NetWorker is
limiting the maximum block size in your Windows environment.  Other postings
in this thread have put you on the correct path.

So, remember the layers!  IMHO, you should use NetWorker's default block
size, and then figure out why some of your platforms are limiting that block
size.

All, please correct me if I err.

Hope this helps.

tl

Terry Lemons
CLARiiON Applications Integration Engineering
        EMC²            
where information lives

4400 Computer Drive, MS D239
Westboro MA 01580
Phone: 508 898 7312
Email: Lemons_Terry AT emc DOT com

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