Veritas-bu

[Veritas-bu] Better than 2:1 on LTO???

2002-08-27 10:48:12
Subject: [Veritas-bu] Better than 2:1 on LTO???
From: Mark.Donaldson AT experianems DOT com (Donaldson, Mark)
Date: Tue, 27 Aug 2002 08:48:12 -0600
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Sure.
 
2:1 is a general number - an average intended more for marketing than
reality.  If you have lots of preallocated data files (blocks full of zeros)
then compressability is pretty good.  Text files compress very well, too
(like your flat file dumps).  Binary files (like executables), jpeg pics,
mp3, and full database blocks don't compress worth anything.
 
Experiment with gzip or compress.  They both use Lempel-Ziv variants for
compression like most tape drives.  Copy a couple representative files to
someplace and compress them.   Compare with the pre-compressed size and
you'll see a huge variations depending on contents.
 
I just stuffed a 2TB database onto ~400G of tape because it was 85% zero
blocks (only 15% real data).  It backs up surprisingly (deceptively) fast,
too.
 
HTH,
-Mark

-----Original Message-----
From: Marx, Keath [mailto:kmarx AT trigon DOT com]
Sent: Tuesday, August 27, 2002 6:59 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Better than 2:1 on LTO???



Greetings All,

I just started backing up a large clustered file server.  Up until this
point we had been backing up system state on AD controllers and exchange2k
servers and the exchange databases.  The most that has fit on a tape up to
this point has been about 180 Gig according to Netbackup.  We added the
cluster which holds about 650 Gig of data.  According to Netbackup, we have
as much as 264 Gig of data on a single tape.  The data on this machine
varies from home directories with the normal stuff stored to departmental
shares with anything and everything.  I do know there are a quite a few
access MDBs and plenty of large SQL flat file dumps.  I have tested restores
of random directories so it looks like I am getting good backups.

Is it feasible that I am getting better than 2:1 on some of this data?  

BM__MailAutoSigThanks.

_____________________________________

<  <mailto:kmarx AT trigon DOT com> kmarx AT trigon DOT com>

Tel: 804-354-3282 / Fax 804-354-7839

Cell Phone 804-513-1431

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<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2>Sure.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff size=2>2:1 
is 
a general number - an average intended more for marketing than reality.&nbsp; 
If 
you have lots of preallocated data files (blocks full of zeros) then 
compressability is pretty good.&nbsp; Text files compress very well, too (like 
your flat file dumps).&nbsp; Binary files (like executables), jpeg pics, mp3, 
and full database blocks don't compress worth anything.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2>Experiment with gzip or compress.&nbsp; They both use Lempel-Ziv 
variants 
for compression like most tape drives.&nbsp; Copy a couple representative files 
to someplace and compress them.&nbsp;&nbsp; Compare with the pre-compressed 
size 
and you'll see a huge variations depending on contents.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff size=2>I 
just 
stuffed a 2TB database onto ~400G of tape because it was 85% zero blocks (only 
15% real data).&nbsp; It backs up surprisingly (deceptively)&nbsp;fast, 
too.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2>HTH,</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff 
size=2>-Mark</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> Marx, Keath 
  [mailto:kmarx AT trigon DOT com]<BR><B>Sent:</B> Tuesday, August 27, 2002 
6:59 
  AM<BR><B>To:</B> veritas-bu AT mailman.eng.auburn DOT edu<BR><B>Subject:</B> 
  [Veritas-bu] Better than 2:1 on LTO???<BR><BR></FONT></DIV>
  <P align=left><FONT face=Arial size=2>Greetings All,</FONT></P>
  <P align=left><FONT face=Arial size=2>I just started backing up a large 
  clustered file server.&nbsp;</FONT> <FONT face=Arial size=2>Up until this 
  point we had been backing up system state on AD controllers and exchange2k 
  servers and t</FONT><FONT face=Arial size=2>he exchange 
  databases.</FONT>&nbsp;<FONT face=Arial size=2> The most that has fit on a 
  tape up to this point has been about 180 Gig according to</FONT> <FONT 
  face=Arial size=2>Netbackup</FONT><FONT face=Arial size=2>.</FONT><FONT 
  face=Arial size=2>&nbsp; We added the cluster which holds about 650 Gig of 
  data.</FONT>&nbsp;<FONT face=Arial size=2></FONT> <FONT face=Arial 
  size=2>A</FONT><FONT face=Arial size=2>ccording</FONT> <FONT face=Arial 
  size=2>to Netbackup, we have as much as 264 Gig of data on a single 
  tape.</FONT>&nbsp;<FONT face=Arial size=2> The data on this machine 
  vari</FONT><FONT face=Arial size=2>es from home directories with the normal 
  stuff stored to departmental shares with anything and 
  everything.</FONT>&nbsp;<FONT face=Arial size=2> I do know there are a quite 
a 
  few access MDBs an</FONT><FONT face=Arial size=2>d plenty of large SQL flat 
  file dumps.</FONT>&nbsp;<FONT face=Arial size=2> I have tested restores of 
  random di</FONT><FONT face=Arial size=2>rectories so it looks like I am 
  getting</FONT> <FONT face=Arial size=2>good backups.</FONT></P>
  <P align=left><FONT face=Arial size=2>Is it feasible that I am getting better 
  than 2:1 on some of this data?</FONT><FONT face=Arial size=2>&nbsp;</FONT> 
</P>
  <P align=left><A name=_MailAutoSig><FONT face=Arial 
  size=2>Thanks.</FONT></A></P>
  <P align=left><FONT face=Tahoma 
  size=1>_____________________________________</FONT></P>
  <P align=left><FONT face=Tahoma color=#0000ff size=1>&lt;</FONT><A 
  href="mailto:kmarx AT trigon DOT com"><U></U><U><FONT face=Tahoma 
color=#0000ff 
  size=1>kmarx AT trigon DOT com</FONT></U></A><FONT face=Tahoma color=#0000ff 
  size=1>&gt;</FONT></P>
  <P align=left><FONT face=Tahoma color=#000000 size=1>Tel: 804-354-3282 / Fax 
  804-354-7839</FONT></P>
  <P align=left><FONT face=Tahoma color=#000000 size=1>Cell Phone 
  804-513-1431</FONT></P>
  <P align=left><FONT face="Comic Sans MS" color=#000000 size=1>This message, 
  including files attached to it, may contain confidential information that is 
  intended only for the use of the ADDRESSEE(S) named above.&nbsp; If you are 
  not an intended recipient, you are hereby notified that any dissemination or 
  copying of the i</FONT><FONT face="Comic Sans MS" color=#000000 
  size=1>n</FONT><FONT face="Comic Sans MS" color=#000000 size=1>formation 
  contained in this message, or the taking of any action in reliance upon the 
  information, is strictly prohibited.&nbsp; If you have received this message 
  in error, please notify the sender immediately and delete the message from 
  your system.&nbsp; Thank yo</FONT><FONT face="Comic Sans MS" color=#000000 
  size=1>u</FONT><FONT face="Comic Sans MS" color=#000000 size=1>.</FONT></P>
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