Veritas-bu

[Veritas-bu] Max Fragment size

2004-02-17 11:53:49
Subject: [Veritas-bu] Max Fragment size
From: Mark.Donaldson AT experianems DOT com (Donaldson, Mark)
Date: Tue, 17 Feb 2004 09:53:49 -0700
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Each fragment is separately tracked in the catalog so having chunks too
small makes for larger catalogs.  I think there's some header information
on-tape per fragment, too, so backup sizes might increase a bit.
 
Still, I think fragments are a big improvement to restore times are are well
worth it.  2 to 4 Gig seems to be a common suggested size.
 
-M

-----Original Message-----
From: Dave Markham [mailto:dave.markham AT icl DOT net]
Sent: Tuesday, February 17, 2004 4:50 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Max Fragment size


I have seen in a few docs about setting this max fragment size to say 2 gig
or anything less than the max file size your OS can handle. How I understand
it is that this will then improve restore times as it can skip along these 2
gig chunks until it finds the section it needs and then begin a read through
of that chunk to find the files needed and start restore.
 
My question is 1. Am I right in my thinking? and 2. What would be the
downside to this? If it improves restore times what reason is there to not
set it?
 
Thanks
 
Environments:-
 
Netbackup 3.2, Solaris 8 Using SUN L1000 4 DLT 7000 tape units
 
Netbackup 4.5 FP6 Solaris 8 Using SUN L25 and LTO drive
 
Dave


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<DIV><SPAN class=311195216-17022004><FONT face=Arial color=#0000ff size=2>Each 
fragment is separately tracked in the catalog so having chunks too small makes 
for larger catalogs.&nbsp; I think there's some header information on-tape per 
fragment, too, so backup sizes might increase a bit.</FONT></SPAN></DIV>
<DIV><SPAN class=311195216-17022004><FONT face=Arial color=#0000ff 
size=2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=311195216-17022004><FONT face=Arial color=#0000ff 
size=2>Still, 
I think fragments are a big improvement to restore times are are well worth 
it.&nbsp; 2 to 4 Gig seems to be a common suggested size.</FONT></SPAN></DIV>
<DIV><SPAN class=311195216-17022004><FONT face=Arial color=#0000ff 
size=2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=311195216-17022004><FONT face=Arial color=#0000ff 
size=2>-M</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
  <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma 
  size=2>-----Original Message-----<BR><B>From:</B> Dave Markham 
  [mailto:dave.markham AT icl DOT net]<BR><B>Sent:</B> Tuesday, February 17, 
2004 4:50 
  AM<BR><B>To:</B> veritas-bu AT mailman.eng.auburn DOT edu<BR><B>Subject:</B> 
  [Veritas-bu] Max Fragment size<BR><BR></FONT></DIV>
  <DIV><FONT face=Arial size=2>I have seen in a few docs about setting this max 
  fragment size to say 2 gig or anything less than the max file size your OS 
can 
  handle. How I understand it is that this will then improve restore times as 
it 
  can skip along these 2 gig chunks until it finds the section it needs and 
then 
  begin a read through of that chunk to find the files needed and start 
  restore.</FONT></DIV>
  <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>My question is 1. Am I right in my thinking? and 
  2. What would be the downside to this? If it improves restore times what 
  reason is there to not set it?</FONT></DIV>
  <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Thanks</FONT></DIV>
  <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Environments:-</FONT></DIV>
  <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Netbackup 3.2, Solaris 8 Using SUN L1000 4 DLT 
  7000 tape units</FONT></DIV>
  <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Netbackup 4.5 FP6 Solaris 8 Using SUN L25 and 
LTO 
  drive</FONT></DIV>
  <DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
  <DIV><FONT face=Arial size=2>Dave</FONT></DIV></BLOCKQUOTE></BODY></HTML>

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