What I can tell you about fragment size is this:
The Veritas consultant that just audited our environment said the Fragment
size for all storage units should be set to 2048.

-----Original Message-----
From: Zufall, Ken [mailto:Ken.Zufall AT ps.bellhowell DOT com]
Sent: Wednesday, October 17, 2001 12:12 PM
To: 'rob AT worman DOT org'; Zufall, Ken
Cc: EBU (E-mail)
Subject: RE: [Veritas-bu] Fragment size settings


I've run into this problem before using Alexandria.  Format was cpio,
fragment size was 2.5GB or thereabout on Solaris 2.5.  When trying to
extract single files from the fragment I was unable to because of the size.

Ken Zufall
Work: 330.202.4113
Cell: 330.465.8113
Pager: 888.896.3272
E-page: 4403037243.8963272 AT pagenet DOT net
<mailto:4403037243.8963272 AT pagenet DOT net> 

                -----Original Message-----
                From:   Rob Worman [mailto:rworman AT yahoo DOT com]
                Sent:   Wednesday, October 17, 2001 2:49 PM
                To:     Zufall, Ken
                Cc:     EBU (E-mail)
                Subject:        Re: [Veritas-bu] Fragment size settings

                Are you saying that a Solaris version that doesn't support
largefiles 
                (ignoring the fact that that vintage of Solaris is no longer
supported 
                by NBU > 3.2...) would not be able to extract files from a
tape that 
                contains a 10 GB tar file?  I can't disprove this fact, but
I can doubt 
                it.  ;-)

                rob

                Zufall, Ken wrote:

                >Fragmentation shouldn't be a problem.  Not sure about NBU,
but other
                >applications I've worked with won't cut a file in the
middle of a fragment,
                >it will continue to end of current file.  So, if you've
already backed up
                >1.5GB and the next file is .7MB, your fragment size will be
2.2GB.  Not
                >using fragmentation will cause problems however, because
some systems
                >(Solaris 2.5 for sure, think they finally fixed in 2.7?)
won't allow file
                >sizes over 2GB in size.  So a 10GB tar file would be
unmanageable in this
                >instance.
                >
                >Ken Zufall
                >Work: 330.202.4113
                >Cell: 330.465.8113
                >Pager: 888.896.3272
                >E-page: 4403037243.8963272 AT pagenet DOT net
                ><mailto:4403037243.8963272 AT pagenet DOT net> 
                >
                >               -----Original Message-----
                >               From:   Rob Worman
[mailto:rworman AT yahoo DOT com]
                >               Sent:   Wednesday, October 17, 2001 11:56 AM
                >               To:     EBU (E-mail)
                >               Subject:        Re: [Veritas-bu] Fragment
size settings
                >
                >               and I know of one price you pay for the use
of fragment
                >size: 
                >               complication of a "non-NBU" tape restore,
i.e. reading from
                >a NetBackup 
                >               tape using only tar.
                >
                >               Without fragmentation, a single 10GB backup
image = a single
                >10GB tar 
                >               file. But with a fragment size of 2000, that
10GB backup
                >image is now 5 
                >               separate tar files.
                >
                >               Unlike the use of multiplexing, fragmenting
is not
                >necessarily a 
                >               "showstopper" when considering this aspect
of NetBackup's DR
                >
                >               capabilities, but if you really want to be
prepared for
                >tar-only 
                >               NetBackup restores, you MUST understand the
effect
                >fragmentation has on 
                >               your media contents. (and you'd be smart to
write a script
                >to automate 
                >               all the tar commands...)
                >
                >               HTH
                >               rob
                >
                >
                >               Kyle Adamski wrote:
                >
                >               > The theory behind the fragment size
setting on the storage
                >unit is to 
                >               > break the larger tar images into smaller
fragments. This
                >allows 
                >               > restores to speed up because in between
the fragments is a
                >tape mark 
                >               > (identifying what is on the fragment) that
will allow NBU
                >to scan the 
                >               > tape faster for what it is looking for vs
reading the
                >entire image. We 
                >               > use them and have them set at 2G....I have
never tested
                >the speed of 
                >               > restores with and without them....I have
just accepted
                >them in 
                >               > principle and assumed that they worked as
advertised. If
                >you have them 
                >               > set at 0(unlimited) there will be no
fragmentation.
                >               >
                >               > Hope that helps.
                >               >
                >               > Kyle A. Adamski
                >               >
                >               > kylea AT firstlogic DOT com
                >               >
                >               > 608.788.8154 x3093
                >               >
                >               > -----Original Message-----
                >               > From: Brochart, Fabrice
[mailto:BrochF AT europe.stortek DOT com]
                >               > Sent: Wednesday, October 17, 2001 9:23 AM
                >               > To: 'Sixbury, Dan'; EBU (E-mail)
                >               > Subject: RE: [Veritas-bu] Fragment size
settings
                >               >
                >               > Hi ,
                >               >
                >               > I read somewhere that restore is more
faster with fragment
                >size 
                >               > (depend on size (depend on backup :) ))
                >               >
                >               > And some customers tells me the same
things but I've never
                >verified.
                >               >
                >               > HTH
                >               >
                >               > F@brice
                >               >
                >               > -----Message d'origine-----
                >               > De : Sixbury, Dan
[mailto:sixbury AT celeritas DOT com ]
                >               > Envoyé : mercredi 17 octobre 2001 16:00
                >               > À : EBU (E-mail)
                >               > Objet : [Veritas-bu] Fragment size
settings
                >               >
                >               > Has anyone seen any benefits for using
fragment size on
                >the storage units,
                >               > or have reasons to not use fragment sizes?
I think the
                >default is
                >               > unlimited, but I noticed that we had some
storage units
                >that were set to
                >               > 2000 while others had the default of
unlimited.
                >               >
                >               > Thanks,
                >               > Dan
                >               >
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                >
                >
                >
                >
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