Veritas-bu

[Veritas-bu] 2 tape drives issue

2003-03-14 08:09:48
Subject: [Veritas-bu] 2 tape drives issue
From: dbase77 AT yahoo DOT com (Feroz F. Basir)
Date: Fri, 14 Mar 2003 13:09:48 +0000 (GMT)
Hi,

OK, I increase my buffer size to 256K and no. of
buffer is 16. Good news is, backup took 38 minutes for
74 GB oracle datafile. Very happy. But not yet as
restore took longer though, in fact it still running
after past 1 hr mark. What am I doing wrong here? Am I
not allow to have win:win situation here? Or win:lose
situation? Do you think I can have balance situation? 

Anybody want to share their experience regarding this
issue?

Thank you in advance.

regards,
feroz 

--- "Donaldson, Mark" <Mark.Donaldson AT experianems DOT com>
wrote: > Drive compression, in Unix, is controlled by
the
> major & minor numbers
> associated with the device files.  These major &
> minor numbers, are
> therefore referenced by the filename. 
> 
> For solaris, look for the /dev/ entry for your
> drives ending in "cbn", ie:
> /dev/rmt/0cbn.  The "c" in "cbn" stands for
> "compressed".  If you use that
> name in your storage unit setup (tpconfig -l), you
> should get compression at
> the drive.
> 
> Yes, I'd definitely increase the 32K to at least 128
> & maybe 256K.  Don't
> screw with the number of buffers unless you're not
> getting sufficient
> throughput - both changes can increase memory usage
> so tweak them up slowly.
> The LTO drive wants big blocks of data for better
> throughput & compression.
> Feeding it 32K teaspoonfuls will starve it.
> 
> Using both drives will speed backup times but you
> have to plan for it in
> policy creation, storage units, pre- & post-schedule
> jobs, etc.  I backup
> nearly 350G of oracle data nightly (direct scsi, no
> network) using four
> streams to two DLT drives (7-8 MB/sec max).  It
> takes about 6.5 hours.  I
> use a NUMBER_DATA_BUFFERS of 64 and
> SIZE_DATA_BUFFERS & NET_BUFFER_SIZE of
> 262144 (256K).
> 
> HTH - Mark
> 
> -----Original Message-----
> From: Feroz F. Basir [mailto:dbase77 AT yahoo DOT com]
> Sent: Thursday, March 13, 2003 10:27 AM
> To: Donaldson, Mark;
> veritas-bu AT mailman.eng.auburn DOT edu
> 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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