Hi
NetWorker uses an internal table that defines the optimum block size for
each output device. That optimum value was determined by Legato from
performing a number of performance tests, I believe.
If NSR_DEV_BLOCK_SIZE_MSG=YES is used*, NetWorker will display the block
size table when nsrmmd is started; use this to see the optimum settings.
As others have noted in this mailing list, using the same volume in multiple
systems can be a problem if those systems do not use identical block sizes
when accessing the device. The most common problem seems to be found when
sharing volumes between some Windows and some UNIX environments, in that
some Windows FC HBAs have a default block size that is smaller than their
UNIX counterparts. I believe that Windows registry settings can be used to
adjust that block size, to allow Windows and UNIX to use the same block
size. I believe that NetWorker uses the same optimum block size table on
all platforms; therefore, NetWorker shouldn't be adjusted, only the
operating system /HBA settings beneath it.
Hope this helps.
tl
Terry Lemons
CLARiiON Application Solutions Engineering
EMC²
where information lives
4400 Computer Drive, MS D239
Westboro MA 01580
Phone: 508 898 7312
Email: Lemons_Terry AT emc DOT com
*see the "Device Parameter Environmental Variables" section in Chapter 5 of
the NetWorker Administrator's Guide for information on how to set NetWorker
environmental variables.
-----Original Message-----
From: Willeat, Todd [mailto:TWilleat AT MHP.SMHS DOT COM]
Sent: Monday, October 07, 2002 8:48 PM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: [Networker] Block size change?
Hi all,
I have a question about setting the block size and didn't see this when I
searched the archives...
We have one server and one storage node (both 6.1.1 running on Win2K).
Currently, both machine are configured to allow 96K blocks. Each machine has
an Exabyte library with Mammoth-2 drives connected to Adaptec SCSI cards.
My question is: Would it beneficial to change to a larger block size?
According to Exabyte, the M2 can handle up to a 240K block. Since NetWorker
requires the block size to be a multiple of 32K, this would leave me with a
maximum possible block size of 224K.
So, should I leave well enough alone, or should I make a change?
Thanks for any opinions!
_______________________________________
/ Todd A. Willeat \
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