Re: [Networker] Effect of changing block size

Hey Terry,

This is actually more of a "what if" question.  I'm not sure what
direction I'm going to be taking.  I'm just trying to figure out what
the effect would be if this was my course of action.  I've read several
times that on a win2k system you "might" be limited to 64k, so that's
were I got that "what if" block size.  I don't have the win2k system or
the FC HBA we're going to be using so I don't have those definitive
answers yet.

Thanks,

Joel

-----Original Message-----
From: lemons_terry AT emc DOT com [mailto:lemons_terry AT emc DOT com] 
Sent: Tuesday, April 08, 2003 4:17 PM
To: Joel Fisher
Cc: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: RE: [Networker] Effect of changing block size

Hi Joel

I'm not directly answering your question, but why not change the default
block size of your Windows 2000 FC HBA devices?  Is 64K a good default
for
your whole environment (disk and tape access)?

Thanks
tl

-----Original Message-----
From: Joel Fisher [mailto:jfisher AT WFUBMC DOT EDU]
Sent: Tuesday, April 08, 2003 4:07 PM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: [Networker] Effect of changing block size


Hey Guys,

 

E450/Solaris 2.6/Solstice Backup 6.1.2

STK9310/9940B drives

 

I was wondering if anyone would know what the effect of lowering the
block size for a device would be.

 

My 9940B drives currently use the default 256k block size.  I would like
to lower them to 64k so I'm compatible with a W2K SAN storage node I
have coming online in the future.  Problem is that I have several(~300)
volumes with data on them and 1000 labeled with the 256k block size.  I
don't foresee a problem with relabeling the ones without data, but I was
unsure of what might happen to the ones with data.  I'm afraid I might
get the "read 256000 bytes, expected 64000, check system device
configuration, disabling forward space record" error.  This obviously
would cause recoveries to be incredible slow.  I would think that since
the tape was labeled at 256k that it wouldn't have a problem
reading(i.e. the NSR_DEV_BLOCK_SIZE_DEVICE_NAME setting only effecting
new labels and tapes).

 

Any clarification on this would be great.  I don't think it should be a
problem, but then again I'm not quit sure.

 

Thanks,

 

Joel


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