ADSM-L

Re: Question about LanFreeBackup

2006-10-17 15:02:15
Subject: Re: Question about LanFreeBackup
From: "Prather, Wanda" <Wanda.Prather AT JHUAPL DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 17 Oct 2006 15:01:13 -0400
Here's something quantifiable:
 
LTO2 drives run at 35-40MB/sec.
LTO3 drives run at 65-70MB/sec.
GigE will support maybe 70 MB/sec, if there isn't too much congestion.
 
So backing up over the SAN instead of Ethernet to an LTO2 drive will still give 
you - 35-40MB/sec.
 
If your problem is Ethernet congestion, you may come out cheaper to buy a 2nd 
NIC for your client and TSM server, and creating a "backup net" network 
segment, that trying to implement Lan-Free, 'cause the Lan-Free may not gain 
any speed for you.
 
(Remember that when Lan-Free clients first became available, many people were 
still backing up over 100MB Ethernet.)
 
 

________________________________

From: ADSM: Dist Stor Manager on behalf of Charles A Hart
Sent: Tue 10/17/2006 9:21 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Question about LanFreeBackup



David,

Was your 4-5 times faster going direct to a Physical Tape Drive?  I ask as
we are moving to all Virtual Tape we are finding the LAN Free backups to
any of the VTL Heads (Dilligent / Falcon Store etc) become the bottleneck.
 I can see a stream to a 3592 or maybe an LTO3 drive do better than a VTL
based LanFree.

I wish someone would make a VTL Head on a Unix box, there's just not the
I/O capacity in these Intel/AMD based linux VTL heads....

Regards,

Charles Hart
UHT - Data Protection





David E Ehresman <deehre01 AT LOUISVILLE DOT EDU>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
10/16/2006 01:15 PM
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


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ADSM-L AT VM.MARIST DOT EDU
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Subject
Re: [ADSM-L] Question about LanFreeBackup






My experience has been different.  Lan Free backups of our Oracle
databases run 4 to 5 times faster than over our lan.  Systems with lots
of small files to backup did not show much improvement going lan free.

David Ehresman

>>> Mark Stapleton <mark.s AT EVOLVINGSOL DOT COM> 10/16/2006 2:01 PM >>>
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
Of
Anker Lerret
>> Remember that LAN-free backups are often no faster
>> than 100MB/1GB Ethernet LAN-based backups. (In a few
>> cases they will actually be slower.)
>
>Mark, can you say some more about that?  We're hoping to start doing
>LAN-free and I was hoping that we could see some nice improvements in
>large backups that go straight to tape.  Are you just talking about
the
>case where the LAN is relatively uncongested and the SAN is
overloaded?
>Or is there something else I'm missing?

I can't say that I've got quantifiable data; I speak from real-world
experience. SAN-based data transfer from disk to tape has been, in the
best of situations, only slightly faster than similar LAN-based data
transfer. As I said earlier, the only advantages I've ever seen to
LAN-free backups have been
1. where the LAN is too congested (or poorly configured) to guantee
reasonable backup speeds
2. the disk storage pool is too small to handle large file backups.
3. you want to guarantee that an entire node's backups go directly to
tape

--
Mark Stapleton (mark.s AT evolvingsol DOT com)
Senior TSM engineer



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