Networker

Re: [Networker] Query in Staging from adv_file

2008-08-19 21:19:52
Subject: Re: [Networker] Query in Staging from adv_file
From: Francis Swasey <Frank.Swasey AT UVM DOT EDU>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Tue, 19 Aug 2008 21:12:58 -0400
With VTL, Networker limits you to one operation at a time per virtual Tape. I've heard tales that if you are lucky enough to issue two recover commands at the exact same instant, that NetWorker can be tricked into doing two restores from the same tape at once.

With the AFTD, you can do multiple concurrent writes and either multiple restores or a stage or a clone at the same time per AFTD. In my environment, I've tested a VTL and it was a lousy performer. I wasted an entire month and had to put up with a lot of pressure from the sales people who really wanted me to spend a small fortune on their appliance when they couldn't make it perform at even one third of the I/O performance of the AFTD on a NexSAN SATABeast.

If I had to do my weekly clones with a VTL that was flat out retrieving data at 35-38MB/second to write to LTO4 tape drives that can do 120MB/second -- I'd be looking for a new job! Thankfully, on my big fileservers with the big savesets, I'm pushing the LTO4's to their limits and my clones are finished in less than 24 hours. Back when I was doing clones from LTO4 to LTO4, these same clones ran for three days. If I was doing that with that bad VTL, I don't know that I'd successfully be able to clone the data during the week before the next round of weekend fulls were written and needed cloning.

In my environment, AFTD wins.

Frank

On 8/19/08 6:16 PM, Curtis Preston wrote:
Well, that significantly decreases the value of AFTDs over VTLs in
NetWorker, now doesn't it?

________________________________________________________
Curtis Preston | VP Data Protection
GlassHouse Technologies, Inc.

T: +1 760 710 2004 | C: +1 760 419 5838 | F: +1 760 710 2009
cpreston AT glasshouse DOT com | www.glasshouse.com
<http://www.glasshouse.com/> Infrastructure :: Optimized



________________________________

From: Francis Swasey [mailto:Frank.Swasey AT uvm DOT edu] Sent: Tuesday, August 19, 2008 2:22 PM
To: EMC NetWorker discussion; Curtis Preston
Subject: Re: [Networker] Query in Staging from adv_file

Sadly, no.  The nsrstage will serialize their use of the single RO side
of the AFTD.  With multiple nsrstage processes trying to access the same
AFTD, you will get alerts that they are waiting for the AFTD.RO
device/volume.

Frank

On 8/19/08 5:10 PM, Curtis Preston wrote:
I understand that each staging process will only use one drive at a
time, but is there a way that he can get more than one staging process
reading from the same AFTD? What if he doesn't do it automatically, but kicks off several nsrstaging
processes manually?  Is that possible?  Will they then each read some
backups and stage them to tape?  (I haven't done much with nsrstage.)





--
Frank Swasey                    | http://www.uvm.edu/~fcs
Sr Systems Administrator        | Always remember: You are UNIQUE,
University of Vermont           |    just like everyone else.
 "I am not young enough to know everything." - Oscar Wilde (1854-1900)


To sign off this list, send email to listserv AT listserv.temple DOT edu and type 
"signoff networker" in the body of the email. Please write to networker-request 
AT listserv.temple DOT edu if you have any problems with this list. You can access the 
archives at http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER