Our use for storage unit groups is for failover in the possiblity that a
media server goes down.  The only backups we have that go direct to a
standard storage unit is the few servers reachable through our
firewalls.  The permissions are only setup for a single destination for
backups.

Since ITC must use drives on the same media server, regardless of group
or standard stu, then this warning would apply to any use of ITC.  It's
not storage group specific.  Any ITC backup has the possiblity of being
reduced to "slowest device performance" rates.  

This warning is confusing and unnecessary in my opinion but I do thank
you for your information.  Thanks, also, to Scott Kendell, for the
eTrack info.  Does seem like a bug.  I didn't try to fix it before
because I thought it might be an artifact of the mixed server versions I
had for a very long time.  I'm all consistent now.

-M

-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Girish
Jorapurkar
Sent: Friday, April 24, 2009 8:02 AM
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Subject: Re: [Veritas-bu] Inline Tape Copy vs Storage Unit Groups (and
otherITC wierdness)


Storage unit group is, typically, used for load-balancing jobs across
mutliple STUs - possibly residing/attached to different Media servers.

Inline-tape-copy creates multiple copies at 'backup time' by writing
each copy to a different media from STU(s) attached to same Media
server. Essentially, it receives a tar stream from a client to the media
server and, then, hands out a copy to each media on the server. There
are couple of points to note: (a) it will use as many drives (if tape is
used) as copies being created, (b) all copies get created in-sync; so
the backup speed for all copies is determined by the slowest one in the
set.

So, when ITC is pointed to STU group, the load-balancing will take
backseat since each copy needs a STU (in the group) from a common Media
server. And, that may result into undesired performance implications.
The warning just highlights that it is not a best practice to do so.

Depending on what version of NetBackup you have and your business
requirements, you may want to look into disk-staging/duplication (6.0),
Storage Lifecycle Policy (6.5.x) to create multiple copies.

/Girish



----- Original Message ----
From: "Donaldson, Mark" <Mark.Donaldson AT Staples DOT com>
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Sent: Thursday, April 23, 2009 1:18:36 PM
Subject: [Veritas-bu] Inline Tape Copy vs Storage Unit Groups (and other
ITC wierdness)

If I create a policy that uses inline-tape-copy to make an offsite copy,
I see two pieces of wierdness that I don't understand.  

The first is that if I select a storage unit group for my destination,
the tape pool, tape owner, etc. grays out.  It's not like my tape pools
are tied to a specific server, they're all setup for *ANY* server so
that shouldn't be an issue.

A work-around seems to be to use a regular STU at first, set-up
everything, then go back and change it to a STU-Group.  When you do
that, it warns, in a pop-up box, "Warning. Selecting storage unit groups
for multiple copies can severely impact performance."

Anybody know the why's and wherefores of these things?

-M
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_______________________________________________
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