You are right Rob.
<><><><><><><><><><><><><><><><><><><><>
David A. Chapa
NetBackup Consultant
DataStaff, Inc.
http://www.consulting.datastaff.com
847 413 1144
---------------------------------------
NBU-LSERV AT datastaff DOT com - Adv. Scripting
http://www.xbpadm-commands.com
-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Rob Worman
Sent: Thursday, October 18, 2001 12:02 PM
To: Kratunis, Anthony; EBU (E-mail)
Subject: RE: [Veritas-bu] Fragment size settings
I think not. AFAIK the only checkpoint restart ability NetBackup can
provide is through the use of multiple streams backing up a single
backup class.
But if I'm wrong and you're right, Holy Hannah we should all be using
fragmentation! :-)
rob
--- "Kratunis, Anthony" <akratunis AT tiaa-cref DOT org> wrote:
> I seem to recall another benefit for fragments. If a backup segment
> fails,
> only that segment needs to be re-tried. So if a 10G file system is
> broken
> into 2G segments, and error is generated during the 9th G, only the
> last 2g
> are retried.
>
> Also, I thought the fragmentation was not used at all on backups to
> disk
> media servers, since a disk is not sequential but random access.
> anthony
>
> -----Original Message-----
> From: Jim Horalek [mailto:jhoralek AT veritas DOT com]
> Sent: Thursday, October 18, 2001 11:59 AM
> To: 'David A. Chapa'; Marelas, Peter; EBU (E-mail)
> Subject: RE: [Veritas-bu] Fragment size settings
>
>
> Disk storage Unit default "2000"
> Media Manager(tape) "0" unlimited.
>
> Tar does require you to be positioned at the start of the
> fragement for the restore. p643 Unix p490 Nt Sysadmin Guide 3.4.
> It actually says beginning of tape.
>
> So the default values are not necessarily the best.
>
> -Jim
>
> > -----Original Message-----
> > From: David A. Chapa [mailto:david AT xbpadm-commands DOT com]
> > Sent: Thursday, October 18, 2001 6:58 AM
> > To: Marelas, Peter; 'Jim Horalek'; EBU (E-mail)
> > Subject: RE: [Veritas-bu] Fragment size settings
> >
> >
> > Yes. That's the way it has been even back when I was with
> > OpenVision as one
> > of their consultants.
> >
> > What it does is lay down image fragment markers on the tape. when
> the
> > restore is performed, netBackup knows which image fragment
> > the file exists
> > in based on its database, so it can seek to the appropriate
> > image fragment,
> > then it begins reading the image fragment looking for the
> > file in question.
> >
> > As far as NBU doing seeking, it was my understanding that the
> > default was
> > 2048, does that mean EOT or unlimited? Or does that mean
> > 2GB? I know we
> > had that as a limit back when 2GB was a hard OS limit, but
> > what does it mean
> > now?
> >
> > Your point is a good one Peter.
> >
> > David
> >
> > <><><><><><><><><><><><><><><><><><><><>
> > David A. Chapa
> > NetBackup Consultant
> > DataStaff, Inc.
> > http://www.consulting.datastaff.com
> > 847 413 1144
> > ---------------------------------------
> > NBU-LSERV AT datastaff DOT com - Adv. Scripting
> > http://www.xbpadm-commands.com
> >
> > -----Original Message-----
> > From: veritas-bu-admin AT mailman.eng.auburn DOT edu
> > [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of
> Marelas,
> > Peter
> > Sent: Thursday, October 18, 2001 1:11 AM
> > To: 'Jim Horalek'; EBU (E-mail)
> > Subject: RE: [Veritas-bu] Fragment size settings
> >
> >
> > Are we sure about this?
> >
> > > The smaller the fragment size the faster the restore "might" be.
> > > Netbackup will make the tape drive "seek" to the correct fragment
> > > without reading the tape between.
> >
> > Are we saying Netbackup can not locate (seek) within a tar file?
> > If so, I would expect restoring a file at the end of a
> > DLT7000 tape (35GB)
> > reading at 5MB/s with 1 large 35GB fragment (1 tar file)
> > would take just
> > under two hour.
> >
> > This doesnt sound right to me especially considering the
> > default fragment
> > size is EOT.
> >
> > Regards
> > Peter Marelas
> >
> > -----Original Message-----
> > From: Jim Horalek [mailto:jhoralek AT veritas DOT com]
> > Sent: Thursday, 18 October 2001 2:49 PM
> > To: EBU (E-mail)
> > Subject: RE: [Veritas-bu] Fragment size settings
> >
> >
> > Well if you think about it, Netbackup streams data to the
> > storage device. If the storage device is a disk you can't
> > exceed the maxfile size for the partition. Tape has no
> > maxfile size. Netbackup will stream until EOT if you let it.
> > Luckly Netbackup will span tapes. Of course a Disk unit is
> > spanned via multiple files.
> >
> > The problem is the restore. If the largest file your extracting
> > from the fragment is larger than the maxfile size for the
> > partition it isn't going to fit. This doesn't happen very often.
> > Usually restoring to an altenate OS client.
> >
> > The Maxfile size is determined by the OS (solaris,sgi,NT) also
> > whether its 32bit or 64bit and the underlying filesystem.
> >
> > The smaller the fragment size the faster the restore "might" be.
> > Netbackup will make the tape drive "seek" to the correct fragment
> > without reading the tape between.
> >
> > Smaller fragments also means more wasted space on the tape.
> >
> > Jim
> >
> >
> > > -----Original Message-----
> > > From: Cornely, David [mailto:David_Cornely AT intuit DOT com]
> > > Sent: Wednesday, October 17, 2001 6:36 PM
> > > To: 'Zufall, Ken'; 'rob AT worman DOT org'
> > > Cc: EBU (E-mail)
> > > Subject: RE: [Veritas-bu] Fragment size settings
> > >
> > >
> > > 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
>
=== message truncated ===
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