You are mixing different statements/procedures together.
The SIZE/NUMBER_DATA_BUFFERS is only done on media servers. It is for
writing data to tape. It defines a memory block/region and creates a
collection area for data. When that collection area is full, it gets set to
the tape drive via the OS driver. The data collection area does not care
what is in it.
The Block sizes are set at the network level. On the client side, it
dictates how the network gets the data to the media server. On the media
server side, you can set NET_BUFFER_SZ to determine how big the collection
unit is (in memory) for storing the network packets.
I have never seen issues with restoring data after tuning a media server.
It may cause issues on older hardware/versions, but I have never seen an
issue with NB4.5 and up on LTO-2 and 3.
As far as a definitive answer on where to find tuning info: It ain't there.
Experience is the best teacher.
Bobby Williams
2205 Peterson Drive
Chattanooga, Tennessee 37421
423-296-8200
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of
Wilkinson,
Alex
Sent: Friday, October 12, 2007 4:33 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Mixing block sizes on LTO Media ... Is it bad ?
Hi all,
We are looking at tuning SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS to keep
our LTO{2,3} drives streaming, however, an interesting question has come up
within our storage group.
Since we interleave blocks from various hosts (grouped by "windows", "unix",
"Exchange", "Oracle", "Sharepoint", etc etc) and the block size will
potentially differ when we implement the "SIZE_DATA_BUFFERS" tuning
parameter, will this cause issues when it comes to doing restores (reading
the tapes) ? i.e. some blocks on the tape will be 64KB and other blocks will
be 256KB.
What are the implications of the aforementioned and is it bad practice ? And
is there and authoritative method to deal with mixed block sizes written to
tape ?
-aW
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