Veritas-bu

[Veritas-bu] Master / Media Servers Explained Please

2005-10-31 10:51:35
Subject: [Veritas-bu] Master / Media Servers Explained Please
From: GreenbergKA AT aetna DOT com (Greenberg, Katherine A)
Date: Mon, 31 Oct 2005 10:51:35 -0500
So, you're setting the storage units to be able to use every drive in
the library, regardless of how many drives there are and then
configuring your policies on a *how many data streams per policy* basis?
I guess if you're library is small that isn't a problem. But when you
start getting upwards of 15 + drives in a single library, even
contemplating configuring them to be able to see all the drives at one
time from one host is asking for performance degradation... unless
you're using multiple HBAs to see the tape.

Any reference I've made to NetBackup and limiting tape drives is not due
to concern about having the same drive used by 2 different servers, but
rather the performance impact of having a single server running too many
tape drives at once. There is only so much I/O you can push thru a
single HBA before you experience diminishing returns.

~Kate



-----Original Message-----
From: Jeff Lightner [mailto:jlightner AT water DOT com] 
Sent: Monday, October 31, 2005 10:42 AM
To: Greenberg, Katherine A; WEAVER, Simon;
veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Master / Media Servers Explained Please


FYI:  We actually define all of our Media Server "storage units" to see
all the drives like the Master server "storage unit" does.   Netbackup
will not try to use the same drive on two different servers in the same
Master/Media environment.   If you had two different Masters that could
be an issue I suppose.   

We limit the number of drives used by the Policy definition rather than
by restricting the number of drives an individual host could potentially
use.   If your backup only has 1 stream it will only use 1 drive no
matter how many the host has available.  

-----Original Message-----
From: Greenberg, Katherine A [mailto:GreenbergKA AT aetna DOT com] 
Sent: Monday, October 31, 2005 10:15 AM
To: WEAVER, Simon; Jeff Lightner; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Master / Media Servers Explained Please

I'm saying from a Performance perspective, you do NOT want a single host
using 25 tape drives at a time. You did state 25 drives, right? To get
the best possible results you would want to throw a couple of Media
servers into your environment to enable you to take advantage of the
drives you're putting in. If you only want to have one server, you won't
need that many drives. 

My .02!

~Kate

-----Original Message-----
From: WEAVER, Simon [mailto:simon.weaver AT astrium.eads DOT net] 
Sent: Monday, October 31, 2005 10:06 AM
To: Greenberg, Katherine A; Jeff Lightner;
veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Master / Media Servers Explained Please



Hi Kate
Ideally, I wanted to have 1 master server, configured to use the robotic
library and use as many drives as possible, leaving spares for restores
/ catalogue backups ect.

So if I have 1 master server with multiple jobs, will it not use all the
available drives? I thought that is what Multiplexing & Max concorrent
jobs was all about?

Simon



-----Original Message-----
From: Greenberg, Katherine A [mailto:GreenbergKA AT aetna DOT com] 
Sent: 31 October 2005 14:40
To: Jeff Lightner; WEAVER, Simon; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Master / Media Servers Explained Please


One more thing... you also don't want to have 25 tape drives all being
used by the same host at the same time, unless you've got 3 or 4 HBAs in
the system. By adding Media servers, you can utilize all the tape drives
at once and limit the number of drives each host is using at the Storage
Unit level.

And Jeff, pre-6.0, there are SSO parameters you can add to vm.conf to
make one host be the SSO scan host all the time (SSO_SCAN_ABLITY). With
6.0, all device allocation is handled on one host (the EMM server, I
think it's
called) so that problem goes away.

~Kate



-----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 Jeff
Lightner
Sent: Monday, October 31, 2005 9:29 AM
To: WEAVER, Simon; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Master / Media Servers Explained Please


MASTER SERVER 
A server that controls all other servers and clients and has most of
your catalogs. Most people also use it as the robotic control host as
well.  It has direct write access to the tape drives and most client
backups go through it via LAN.

MEDIA SERVER
A server that has direct write access to the tape drives.  The main
reason we have them here is because we have SAN and large database
servers.   By configuring them as Media Servers we avoid using LAN to do
backups.   Also it allows for direct restore.   They also contain some
catalog information for the backups done on them.   You could have LAN
clients backed up on media servers to take advantage of additional CPU
and I/O backplane but we don't.

The main PRO to MEDIA SERVERS is as indicated above.  You can backup and
restore using drives via SAN so that you don't impact your LAN.  Also by
using CPU and backplane of a separate server you do get some performance
improvement.

The CONs to MEDIA SERVERS:
1) The SCAN HOST floats so to get it back the way you want you have to
down the drive on all of them then up it on the one that you want first
then up it on all others.  This can be scripted so is not a huge problem
- just an annoyance.
2) As noted they do have some catalog information so you have to be
careful not to retire without migrating its catalogs if you need access
in future (especially if you have any LAN clients using them rather than
the MASTER SERVER).

Also I gather from comments on this thread that you don't have to do
full MEDIA SERVER any more for the purpose for which we use them (just
to back themselves up - no LAN clients).  If you intend to do the same
make sure you get the cheaper license for that purpose.

-----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 WEAVER,
Simon
Sent: Monday, October 31, 2005 7:44 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Master / Media Servers Explained Please


Hi Everyone
Presently, firefighting NBU 5.x and 3.4 Master Servers with various
backup issues which I will not bore you all about yet :-)

I have just discovered a site that I work with has approx 10 MEDIA
SERVERS and many master servers.

I am presently using 2 master servers and am being told that I will need
to implement Many media servers asap.

But my concerns are costs and what benefit the media servers will give
me. I will be implementing a 25 drive 700 TL system in the near future,
and wanted to make a fault tolerant Master Server to perform the job,
but can anyone give me any pros / cons as I feel uneasy about having
many 2003 Media Servers on board. Also, costs are going to be an issue,
so if anyone has any reasons or limitations as to why 1 master server
could not backup / restore many clients, please do let me know

Thanks everyone for any input :-)

Simon 



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disseminate or otherwise deal with it. Please notify the sender by
return email. The views of the author may not necessarily constitute the
views of EADS Astrium Limited. Nothing in this email shall bind EADS
Astrium Limited in any contract or obligation.

EADS Astrium Limited, Registered in England and Wales No. 2449259
Registered Office: Gunnels Wood Road, Stevenage, Hertfordshire, SG1 2AS,
England