This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
------_=_NextPart_001_01C24DD8.C4372C20
Content-Type: text/plain
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
This message, including files attached to it, may contain confidential
information that is intended only for the use of the ADDRESSEE(S) named
above. If you are not an intended recipient, you are hereby notified that
any dissemination or copying of the information contained in this message,
or the taking of any action in reliance upon the information, is strictly
prohibited. If you have received this message in error, please notify the
sender immediately and delete the message from your system. Thank you.
------_=_NextPart_001_01C24DD8.C4372C20
Content-Type: text/html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=US-ASCII">
<TITLE>Better than 2:1 on LTO???</TITLE>
<META content="MSHTML 6.00.2719.2200" name=GENERATOR></HEAD>
<BODY>
<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> </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.
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.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff
size=2>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.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </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). It backs up surprisingly (deceptively) fast,
too.</FONT></SPAN></DIV>
<DIV><SPAN class=100314214-27082002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </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. </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> <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> We added the cluster which holds about 650 Gig of
data.</FONT> <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> <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> <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> <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> </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><</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>></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. 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. If you have received this message
in error, please notify the sender immediately and delete the message from
your system. 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>
<P align=left></P></BLOCKQUOTE></BODY></HTML>
------_=_NextPart_001_01C24DD8.C4372C20--
|