Veritas-bu

[Veritas-bu] Slow Performance of Restore

2002-04-11 12:52:01
Subject: [Veritas-bu] Slow Performance of Restore
From: larry.kingery AT veritas DOT com (Larry Kingery)
Date: Thu, 11 Apr 2002 12:52:01 -0400 (EDT)
It's not half duplex that's so bad (though it is a good bit slower
than full).  The real problem is when the client and switch disagree
(this would probably be your 200KB/s, I've usually seen it as
150-200). 

For example, if the switch thinks it can do full, but the client will
only do half then the switch will end up sending a lot of packets
(probably TCP ACKs) when the client isn't ready.  These will of course
fail and have to be retried/retransmitted.  This is when it gets real
ugly, sending the same thing over and over only makes the problem
exponentially worse.  

To repeat what Dave said, "never, ever use auto negotiate".


Dave High writes:
> Hi Phil, 
> 
> Typically a half duplex NIC runs at between 500 - 800Kb per second depending
> on your machine and network. At 500Kbps, you are looking at about 1.8 Gig
> per hour. Sometimes Windows machines at half duplex are even slower than 500
> Kbps by the way. I have seen rates of 200 - 300 Kbps.. 
> 
> It is highly recommended that the NIC be forced to 100Mbit both at the card
> level, and at the switch level and never, ever use auto negotiate. You would
> be surprised how many times I have gone onsite to troubleshoot slow backup
> rates only to have the network guy assure me that Auto Negotiate works just
> fine, then I have to prove to them that it is stuck in Half Duplex... this
> usually takes about two days to convince them to double check and test, and
> it usually clears up the problem.  
> 
> Anyway, get the card set to 100Mbit full and retry the restore. You should
> be able to do between 2 - 4 Megs per second. Use Perfmon to look at NIC
> rates while it is running, or use the Unix Activity Monitor (Job Monitor) to
> see how fast the backup is running. You should get nearly the same speed on
> restores (depending on Multiplexing settings) as you do on backups. 
> 
> Other than that, the restore information from NBU is really limited. This
> has been a pet peeve of mine for the longest time. NBU 4.5 addresses this
> issue somewhat, but the information is still not as full as the backup
> information. 
> 
> d. 
> 
> __________
> dave high
> VERITAS Enterprise Consulting
> 702.683.7733
>  
> Unix IS user friendly, it's just VERY picky about who it chooses as friends
>  
> 
> > -----Original Message-----
> > From: Weber, Philip [mailto:Philip.Weber AT egg DOT com]
> > Sent: Thursday, April 11, 2002 5:34 AM
> > To: 'veritas-bu AT mailman.eng.auburn DOT edu'
> > Subject: [Veritas-bu] Slow Performance of Restore
> > 
> > Hi,
> > 
> > I am running a restore of an NT client, approx 110 Gb expected; over the
> > last 8 hours it has done 10 Gb which seems a tad slow.  Can anyone offer
> > any
> > hints on how I might troubleshoot this e.g. to check throughput, see how
> > much is remaining, or improve performance in the future?  I thought I had
> > seen this topic discussed recently on the list but can't find it on the
> > archives.
> > 
> > ...
> > 
> > Since I started writing this email I've discovered that the NT client has
> > it's 100 MB interface set to Half-Duplex which I guess is what is causing
> > the problem.  My other questions stand, though, is there any source of
> > information on restore progress?
> > 
> > thanks, Phil
> > 
> > PS Solaris 2.6 master & media servers with 1000 MB interfaces, L700 with
> > DLT
> > Drives.
> > 
> > Phil Weber
> > IT Infrastructure Unix Systems Engineer
> > 
> > Phone: 01384 26 4136
> > Mobile: n/a
> > 
> > 
> > 
> > 
> > This private and confidential e-mail has been sent to you by Egg.
> > The Egg group of companies includes Egg Banking plc
> > (registered no. 2999842), Egg Financial Products Ltd (registered
> > no. 3319027) and Egg Investments Ltd (registered no. 3403963) which
> > carries out investment business on behalf of Egg and is regulated
> > by the Financial Services Authority.
> > Registered in England and Wales. Registered offices: 1 Waterhouse Square,
> > 138-142 Holborn, London EC1N 2NA.
> > If you are not the intended recipient of this e-mail and have
> > received it in error, please notify the sender by replying with
> > 'received in error' as the subject and then delete it from your
> > mailbox.
> > 
> > _______________________________________________
> > Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> > http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu

-- 
Larry Kingery 
           Proofread carefully to see if you any words out.