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It's all guesswork. Seriously, I don't think you'll ever get a solid
recommendation until NB keeps more usage data. Vendors can tell you =
number
of "full pass writes" a tape is rated for and that sort of thing, but =
how do
I translate that into NetBackup's max mounts? In NB, a mount for write =
is a
mount for write, whether it writes 1MB or 100GB. =20
=20
NB usually does a pretty good job of filling up tapes and if you have =
lots
of clients running at the same time with multiplexing, etc. it's likely =
your
drives will mount a tape and write it through to the end. But what if =
the
data flow tapers off? Shoe-shining is going to stress the cartridge a =
lot
more than streaming. And perhaps you later mount that tape for a few =
small
backups...you see how difficult it is to keep track of this ;) I think =
NB
*could* keep this data...(psst, Veritas guys, this would be a cool =
feature)
=20
We use 125 mounts for LTO (which is also what we used for DLT). Maybe =
I
could get more mounts. I suspect I could. But the value of the data =
is
nearly infinite in comparison to the cost of the tape, so this decision =
is
easy. On the one hand, maybe I spend too much for tapes. On the other
hand, I'd rather do that than lose some critical enterprise data ("But =
boss,
I saved $50!") Even with multiple in-line copies, off-siting for DR, =
etc. I
still feel that way ;) Gaaaa - I hate this issue because I can't stand
throwing away tapes that might still be serviceable but how do you =
know...
=20
Some of the STK drives (99xx) use 300 max mounts. IBM's 3590s use a =
higher
number as well. =20
=20
Out of curiosity, what do you use for number of hours to clean? I use =
300.
I haven't noticed any correlation between the (few) media problems =
we've had
and cleaning hours.
=20
I like your idea of using "old tapes" for development or non-critical =
data.
I hadn't thought of that. =20
=20
-----Original Message-----
From: Mark Eisenhardt [mailto:Mark_Eisenhardt AT stoneybrookfl DOT com]
Sent: Wednesday, December 04, 2002 5:26 PM
To: White, Steve; 'Jonas Bl=E5berg'; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Max number of mounts for an LTO tape?
Just thought I'd throw my 2 cents in on this because I've never heard =
of any
rule of thumb on the number of mounts/usage
for tapes.=20
I've seen some other backup software that sets the default to 360. ie
Omniback
For Netbackup we set our production pool to 120 mounts (Business =
Critical
Data)
The development pool is set to 360 mounts (Non-Critical Businesss Data)
Also we have been on Veritas NBU for 1 1/2 years and have yet to exceed =
50
uses per tape, and no tape failures, so it will be a while before we =
can
establish an SOP for this.
=20
Mark
-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of White, =
Steve
Sent: Wednesday, December 04, 2002 10:05 AM
To: 'Jonas Bl=E5berg'; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Max number of mounts for an LTO tape?
We use 500 mounts and thus far don't seem to have an excessive amount =
of
tape failures.
-----Original Message-----
From: Jonas Bl=E5berg [mailto:jonas.blaberg AT cellnetwork DOT com]
Sent: Wednesday, December 04, 2002 4:25 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Max number of mounts for an LTO tape?
Hello!=20
About how high should the max number of mounts be configured for LTO =
tapes?
Of course there is no rule saying tapes are destroyed after exactly X
mounts/unmounts, but I want to know someone else's opinion regarding =
this.
/jonas=20
Jonas Bl=E5berg=20
Cell Network Sverige AB=20
Kruthusgatan 17,6=20
S-411 04 G=F6teborg=20
jonas.blaberg AT cellnetwork DOT com=20
office: +46-(0)31-739 84 54=20
mobile: +46-(0)709-95 00 68=20
------------------------------------------------------------------------=
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This email is confidential and may be legally privileged.
It is intended solely for the addressee. Access to this email by anyone
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If you are not the intended recipient, any disclosure, copying, =
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or any action omitted or taken in reliance on it, is prohibited and may =
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<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff size=2>It's
all guesswork. Seriously, I don't think you'll ever get a solid
recommendation until NB keeps more usage data. </FONT></SPAN><SPAN
class=753462103-05122002><FONT face=Arial color=#0000ff size=2>Vendors can tell
you number of "full pass writes" a tape is rated for and that sort of thing,
but
how do I translate that into NetBackup's max mounts? </FONT></SPAN><SPAN
class=753462103-05122002><FONT face=Arial color=#0000ff size=2>In NB, a mount
for write is a mount for write, whether it writes 1MB or 100GB.
</FONT></SPAN></DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff size=2>NB
usually does a pretty good job of filling up tapes and if you have lots of
clients running at the same time with multiplexing, etc. it's likely your
drives
will mount a tape and write it through to the end. But what if the data
flow tapers off? Shoe-shining is going to stress the cartridge a lot more
than streaming. And perhaps you later mount that tape for a few small
backups...you see how difficult it is to keep track of this ;) I think NB
*could* keep this data...(psst, Veritas guys, this would be a cool
feature)</FONT></SPAN></DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN><SPAN class=753462103-05122002><FONT face=Arial
color=#0000ff size=2></FONT></SPAN><SPAN class=753462103-05122002><FONT
face=Arial color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff size=2>We
use
125 mounts for LTO (which is also what we used for DLT). Maybe I could
get
more mounts. I suspect I could. </FONT></SPAN><SPAN
class=753462103-05122002><FONT face=Arial color=#0000ff size=2>But the value of
the data is nearly infinite in comparison to the cost of the tape, so this
decision is easy. On the one hand, maybe I spend too much for
tapes.
On the other hand, I'd rather do that than lose some critical enterprise data
("But boss, I saved $50!") Even with multiple in-line copies, off-siting
for DR, etc. I still feel that way ;) Gaaaa - I hate this issue because I
can't stand throwing away tapes that might still be serviceable but how do you
know...</FONT></SPAN></DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff size=2>Some
of the STK drives (99xx) use 300 max mounts. IBM's 3590s use a higher
number as well. </FONT></SPAN></DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff size=2>Out
of
curiosity, what do you use for number of hours to clean? I use 300.
I haven't noticed any correlation between the (few) media problems we've had
and
cleaning hours.</FONT></SPAN></DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff size=2>I
like
your idea of using "old tapes" for development or non-critical data. I hadn't
thought of that. </FONT></SPAN></DIV>
<DIV><SPAN class=753462103-05122002><FONT face=Arial color=#0000ff
size=2></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> Mark Eisenhardt
[mailto:Mark_Eisenhardt AT stoneybrookfl DOT com]<BR><B>Sent:</B> Wednesday,
December
04, 2002 5:26 PM<BR><B>To:</B> White, Steve; 'Jonas Blåberg';
veritas-bu AT mailman.eng.auburn DOT edu<BR><B>Subject:</B> RE: [Veritas-bu]
Max
number of mounts for an LTO tape?<BR><BR></FONT></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff
size=2>Just
thought I'd throw my 2 cents in on this because I've never heard of any rule
of thumb on the number of mounts/usage</FONT></SPAN></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff size=2>for
tapes. </FONT></SPAN></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff
size=2>I've
seen some other backup software that sets the default to 360. ie
Omniback</FONT></SPAN></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff size=2>For
Netbackup we set our production pool to 120 mounts (Business Critical
Data)</FONT></SPAN></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff size=2>The
development pool is set to 360 mounts (Non-Critical Businesss
Data)</FONT></SPAN></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff
size=2>Also
we have been on Veritas NBU for 1 1/2 years and have yet to exceed 50 uses
per
tape, and no tape failures, so it will be a while before we can establish an
SOP for this.</FONT></SPAN></DIV>
<DIV><SPAN class=930301301-05122002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=930301301-05122002><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>
veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]<B>On Behalf Of
</B>White,
Steve<BR><B>Sent:</B> Wednesday, December 04, 2002 10:05 AM<BR><B>To:</B>
'Jonas Blåberg'; veritas-bu AT mailman.eng.auburn DOT
edu<BR><B>Subject:</B> RE:
[Veritas-bu] Max number of mounts for an LTO tape?<BR><BR></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=592590215-04122002>We
use 500 mounts and thus far don't seem to have an excessive amount of tape
failures.</SPAN></FONT></DIV>
<BLOCKQUOTE>
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> Jonas Blåberg
[mailto:jonas.blaberg AT cellnetwork DOT com]<BR><B>Sent:</B> Wednesday,
December
04, 2002 4:25 AM<BR><B>To:</B>
veritas-bu AT mailman.eng.auburn DOT edu<BR><B>Subject:</B> [Veritas-bu]
Max
number of mounts for an LTO tape?<BR><BR></FONT></DIV><!-- Converted from
text/rtf format -->
<P><FONT face=Arial size=2>Hello!</FONT> </P>
<P><FONT face=Arial size=2>About how high should the max number of mounts
be configured for LTO tapes? Of course there is no rule saying tapes are
destroyed after exactly X mounts/unmounts, but I want to know someone
else's opinion regarding this.</FONT></P>
<P><FONT face=Arial size=2>/jonas</FONT> </P><BR>
<P><FONT face=Arial size=2>Jonas Blåberg</FONT> <BR><FONT face=Arial
size=2> Cell Network Sverige AB</FONT> <BR><FONT face=Arial
size=2> Kruthusgatan 17,6</FONT> <BR><FONT face=Arial size=2>
S-411 04 Göteborg</FONT> <BR><FONT face=Arial
size=2>jonas.blaberg AT cellnetwork DOT com</FONT> <BR><FONT face=Arial
size=2>office: +46-(0)31-739 84 54</FONT> <BR><FONT face=Arial
size=2>mobile: +46-(0)709-95 00 68</FONT> </P><BR></BLOCKQUOTE>
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