Veritas-bu

[Veritas-bu] RE: [NBUADV-L]: compression and DLT 7000

2001-02-19 08:15:36
Subject: [Veritas-bu] RE: [NBUADV-L]: compression and DLT 7000
From: David A. Chapa david AT datastaff DOT com
Date: Mon, 19 Feb 2001 05:15:36 -0800 (PST)
Clifford:

After talking with my client over the weekend and 
finding out what they were backing up, I found that 
they were some db files.  These files had a lot 
of 'white space' or otherwise called sparse files that 
when backed up will compress much more than the 
advertised drive spec.

David

Quoting Dustin Scharf <dusty AT veritas DOT com>:

> Absolutely.  For example, at a previous job we 
rutinely (sp?) got 15:1
> compression from a an application using a cobol 
database... tons of white
> (blank) space in the files.  we would get well over 
300GB of data on a
> single DLT tape.  Conversely, try backing up a bunch 
of zip files or
> already
> compressed files... you won't get near the 70GB.
> 
> Dustin
> 
> Dustin Scharf
> Veritas Education Services
> dusty AT veritas DOT com
> 
> 
> -----Original Message-----
> From: Stephen Dvorak [mailto:sdvorak AT veritas DOT com]
> Sent: Friday, February 16, 2001 3:40 PM
> To: 'David A. Chapa'; clifford thurber;
> veritas-bu AT mailman.eng.auburn DOT edu
> Cc: nbu-lserv AT datastaff DOT com
> Subject: RE: [NBUADV-L]: compression and DLT 7000
> 
> 
> The 70GB limit on DLT 7000 drives is assuming 2:1 
compression.  The drive
> is
> capable of producing greater compression rates than 
this.  Thus, if the
> data
> is highly compressable, the drive should be able to 
get better than 2:1.
> Steve
> 
> -----Original Message-----
> From: David A. Chapa [mailto:david AT datastaff DOT com]
> Sent: Friday, February 16, 2001 2:33 PM
> To: clifford thurber; veritas-
bu AT mailman.eng.auburn DOT edu
> Cc: nbu-lserv AT datastaff DOT com
> Subject: RE: [NBUADV-L]: compression and DLT 7000
> 
> 
> I've seen the same thing at another customer's 
site...the Veritas SE that
> was onsite before me said that it may be due to some 
HIGHLY compressable
> data...I'm not sure I know what that means since I 
haven't had an
> opportunity to research it further.
> 
> David
> 
> <><><><><><><><><><><><><><><><><><><><>
> David A. Chapa
> Consulting Manager
> DataStaff, Inc.
> 847 413 1144
> http://www.consulting.datastaff.com
> ---------------------------------------
> NBU-LSERV AT datastaff DOT com - Adv. Scripting
> 
> -----Original Message-----
> From: owner-nbu-lserv AT datastaff DOT com
> [mailto:owner-nbu-lserv AT datastaff DOT com]On Behalf Of 
clifford thurber
> Sent: Friday, February 16, 2001 2:05 PM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Cc: nbu-lserv AT datastaff DOT com
> Subject: [NBUADV-L]: compression and DLT 7000
> 
> 
> Hello,
> We are using Netbackup 3.2 on Solaris 7 with Quantam 
DLT 7000 Drives. We
> have the following line in our st.conf file
> DLT7k-data =    
1,0x36,0,0x9639,4,0x84,0x83,0x0,0x85,3;
> Which I believe denotes that we have 70GB of storage 
in  compressed mode. I
> also believe that this is the theoretical limiton DLT 
7000's using
> compression. The confusing part is that when I run 
the media list report I
> see tapes that are 87GB, 129GB and 111GB. Can someone 
tell me how this is
> even possible? Veritas was not able to give me an 
answer to this? Thanks in
> advance I will summarize.
> Clifford
> 
> ------------------------------------------------------
-
> NBU-LSERV AT datastaff DOT com - Advanced NetBackup Scripting
> http://www.consulting.datastaff.com/adv_script_site
> 
> 
> ------------------------------------------------------
-
> NBU-LSERV AT datastaff DOT com - Advanced NetBackup Scripting
> http://www.consulting.datastaff.com/adv_script_site
> ------------------------------------------------------
-
> NBU-LSERV AT datastaff DOT com - Advanced NetBackup Scripting
> http://www.consulting.datastaff.com/adv_script_site
> _______________________________________________
> Veritas-bu maillist  -  Veritas-
bu AT mailman.eng.auburn DOT edu
> 
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bu
> 



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
David A. Chapa
Consulting Manager
DataStaff, Inc.
847 413 1144



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