Veritas-bu

[Veritas-bu] 2 tape drives issue

2003-03-13 13:17:20
Subject: [Veritas-bu] 2 tape drives issue
From: mhickey AT glasshousetech DOT com (Mark Hickey)
Date: Thu, 13 Mar 2003 13:17:20 -0500
You are probably getting killed by having compression checked.  This makes 
netbackup run a compression algorithm over the data, which is then sent to tape 
(which in most cases tries to compress it again!).
 
Since you are not backing up network clients you are doing the software 
compression (which is in most cases superfluous because of the hardware 
compression) on the backup server.  Since compression is memory intensive, it 
also contends with backup for memory as well as CPU cycles.
 
 

        -----Original Message----- 
        From: Feroz F. Basir [mailto:dbase77 AT yahoo DOT com] 
        Sent: Thu 3/13/2003 12:27 PM 
        To: Donaldson, Mark; veritas-bu AT mailman.eng.auburn DOT edu 
        Cc: 
        Subject: RE: [Veritas-bu] 2 tape drives issue
        
        

        Hi,
        
        Thank you for replying. How do I go about turn on the
        LTO drive compression, as these drives are attach to
        L25 tape library at the back. Any command I can use? I
        also going to uncheck the netbackup compression see
        how it goes tonite. Regarding the buffer setting, I'm
        using the default which I think 32K. Do you think this
        buffer setting cause the extra time? I attached the
        tape library to our SUN box and ONLY backup data from
        the SUN. No network backup or so ever. I'm very
        suprise about the time that I have here.
        
        What negative impact can I get if I use bigger buffer
        size? And if I use both drives at the same how's the
        writing work? Does it write at the same time or one
        after another?
        
        I'll let you know the outcome tomorrow morning.
        
        Thank you.
        
        regards,
        feroz
        
         --- "Donaldson, Mark"
        <Mark.Donaldson AT experianems DOT com> wrote: > Don't use
        the Netbackup client compression.  It's
        > software based and causes
        > a high client load, slowing the backups.  Your LTO
        > drive is capable of
        > hardware compression, use that.
        >
        > LTO is good for about 15 MB/sec native, perhaps
        > 25-30MB streaming rates if
        > you can get the data to it fast enough & the data is
        > decently compressible.
        > So 74G at 15 MB/sec is only 84 minutes so you're
        > really underperforming.
        >
        > Check your buffer sizes.  For my LTO drives, I'm
        > using 256K buffers & it
        > makes a big performance difference.  Check this
        > whitepaper for a description
        > buffer sizes & counts.  Make sure to set the buffers
        > for both client & media
        > server.
        > http://seer.support.veritas.com/docs/183702.htm  If
        > your system is
        > Windows, check out this instead:
        > http://seer.support.veritas.com/docs/244652.htm
        >
        > Also consider the path from client to media server.
        > If it's standard
        > ethernet, it's only capable of about 10MB/sec, and
        > your drive will be
        > underutilized.  Consider Gigabit ethernet if
        > possible.
        >
        > That should be enough to start with - post back any
        > results you get.
        > -M
        >
        > -----Original Message-----
        > From: Feroz F. Basir [mailto:dbase77 AT yahoo DOT com]
        > Sent: Thursday, March 13, 2003 9:54 AM
        > To: Donaldson, Mark;
        > veritas-bu AT mailman.eng.auburn DOT edu
        > Subject: RE: [Veritas-bu] 2 tape drives issue
        >
        >
        > Hi,
        >
        > LTO drive.
        >
        > regards,
        > feroz
        >
        >  --- "Donaldson, Mark"
        > <Mark.Donaldson AT experianems DOT com> wrote: > What kind
        > of
        > drive (DLT, LTO, etc.) in the L25?
        > > -M
        > >
        > > -----Original Message-----
        > > From: Feroz F. Basir [mailto:dbase77 AT yahoo DOT com]
        > > Sent: Thursday, March 13, 2003 4:15 AM
        > > To: veritas-bu AT mailman.eng.auburn DOT edu
        > > Subject: RE: [Veritas-bu] 2 tape drives issue
        > >
        > >
        > > Hi,
        > >
        > > Thank you to all who replied to my problem. I got
        > it
        > > to work to use both tape drives at the same time
        > > using
        > > 2 different policies.
        > >
        > > Backup took about 5 hrs to finish for 74 GB data
        > on
        > > 1
        > > tape. I wonder myself if I can improve the time
        > > here.
        > > I only backup oracle data files. Plus select to
        > > compress. Is this normal behaviour. I'm using NB
        > 4.5
        > > business server on SUN storedge L25 tape library
        > > with
        > > 2 drives.
        > >
        > > Thank you again.
        > >
        > > regards,
        > > feroz
        > >
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