Veritas-bu

[Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498 - 1 msg

2003-09-11 15:33:38
Subject: [Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498 - 1 msg
From: scott.kendall AT abbott DOT com (scott.kendall AT abbott DOT com)
Date: Thu, 11 Sep 2003 14:33:38 -0500
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I've actually heard this before as well (or maybe read it somewhere), but 
it is only when the drive becomes available...

In an MPX situation, when one job ends, if another queued job can MPX onto 
the same tape (storage unit, retention, MPX values allow it) that queued 
job will go active instead of the higher priority job.  The fact of the 
matter is, during most backup windows, there is almost always a job that 
can do this and dozens or even hundreds of jobs can complete this way 
before the tape drive actually becomes available for a higher priority 
job.

This occurs, not only with restores, which are supposedly a priority over 
backups, but also with higher priority backups.

It appears that there is a fundamental flaw in the way priorities are 
handled, but how do you do it better?  I don't know if I would want a 
drive with 5 active jobs MPX'ing to it, to go down to 4, 3, 2, 1 until it 
is 0 and becomes available (this could take some time, at which point the 
drive is working at partial capacity and queued jobs are just sitting 
there), just because a higher priority job is queued up.

Stopping (or pausing) a backup and making the drive available to be used 
for a restore and then continuing a backup later is nice, but it doesn't 
address the issue with lower priority backups going active over higher 
priority backups if the higher priority backup doesn't use the same 
storage unit or retention or doesn't have a high enough MPX value.

Leaving unallocated (from a Storage Unit's perspective) tape drives isn't 
always an option in an SSO environment with a high percentage of SAN Media 
Servers.


- Scott





"Goldfarb, Josh" <Josh.Goldfarb AT blackrock DOT com>
Sent by: veritas-bu-admin AT mailman.eng.auburn DOT edu
09/11/2003 07:12 AM

 
        To:     <veritas-bu AT mailman.eng.auburn DOT edu>
        cc: 
        Subject:        [Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498 - 1 msg


IT is my understanding that a restore is the highest priority.  If all
your drives are taken from backups it will grab the next available
drive. 


-----Original Message-----
From: veritas-bu-request AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-request AT mailman.eng.auburn DOT edu] 
Sent: Wednesday, September 10, 2003 1:02 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Veritas-bu digest, Vol 1 #2498 - 1 msg


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Today's Topics:

   1. Re: Prioritizing Restores over Backups in 4.5 (Wayne T Smith)

--__--__--

Message: 1
Date: Wed, 10 Sep 2003 09:38:34 -0400
From: Wayne T Smith <WTSmith AT maine DOT edu>
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Prioritizing Restores over Backups in 4.5

Hart, Charles wrote, in part:

> Oh.. I can't hold it in.  I'm a fairly new user to Netbackup 4.5FP#, 
> have been using TSM for a couple years, and I find this troubling.  In
the TSM world Restores Always take precedence.  If another task is using
a drive in TSM, TSM will make a drive available, then once the restore
is complete TSM will know where it left off on the prior task.
> 
> I feel like I've just traded in my Cadillac for a KIA.....

You did!  Join the club.  Nothing is perfect, though that Cadillac was 
pretty good.  ;-)

cheers, wayne



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<br><font size=2 face="Arial">I've actually heard this before as well (or maybe 
read it somewhere), but it is only when the drive becomes available...</font>
<br>
<br><font size=2 face="Arial">In an MPX situation, when one job ends, if 
another queued job can MPX onto the same tape (storage unit, retention, MPX 
values allow it) that queued job will go active instead of the higher priority 
job. &nbsp;The fact of the matter is, during most backup windows, there is 
almost always a job that can do this and dozens or even hundreds of jobs can 
complete this way before the tape drive actually becomes available for a higher 
priority job.</font>
<br>
<br><font size=2 face="Arial">This occurs, not only with restores, which are 
supposedly a priority over backups, but also with higher priority 
backups.</font>
<br>
<br><font size=2 face="Arial">It appears that there is a fundamental flaw in 
the way priorities are handled, but how do you do it better? &nbsp;I don't know 
if I would want a drive with 5 active jobs MPX'ing to it, to go down to 4, 3, 
2, 1 until it is 0 and becomes available (this could take some time, at which 
point the drive is working at partial capacity and queued jobs are just sitting 
there), just because a higher priority job is queued up.</font>
<br>
<br><font size=2 face="Arial">Stopping (or pausing) a backup and making the 
drive available to be used for a restore and then continuing a backup later is 
nice, but it doesn't address the issue with lower priority backups going active 
over higher priority backups if the higher priority backup doesn't use the same 
storage unit or retention or doesn't have a high enough MPX value.</font>
<br>
<br><font size=2 face="Arial">Leaving unallocated (from a Storage Unit's 
perspective) tape drives isn't always an option in an SSO environment with a 
high percentage of SAN Media Servers.</font>
<br>
<br>
<br><font size=2 face="Arial">- Scott</font>
<br>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td>
<td><font size=1 face="sans-serif"><b>&quot;Goldfarb, Josh&quot; 
&lt;Josh.Goldfarb AT blackrock DOT com&gt;</b></font>
<br><font size=1 face="sans-serif">Sent by: veritas-bu-admin AT 
mailman.eng.auburn DOT edu</font>
<p><font size=1 face="sans-serif">09/11/2003 07:12 AM</font>
<br>
<td><font size=1 face="Arial">&nbsp; &nbsp; &nbsp; &nbsp; </font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; To: &nbsp; 
&nbsp; &nbsp; &nbsp;&lt;veritas-bu AT mailman.eng.auburn DOT edu&gt;</font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; cc: &nbsp; 
&nbsp; &nbsp; &nbsp;</font>
<br><font size=1 face="sans-serif">&nbsp; &nbsp; &nbsp; &nbsp; Subject: &nbsp; 
&nbsp; &nbsp; &nbsp;[Veritas-bu] RE: Veritas-bu digest, Vol 1 #2498 - 1 
msg</font></table>
<br>
<br>
<br><font size=2 face="Courier New">IT is my understanding that a restore is 
the highest priority. &nbsp;If all<br>
your drives are taken from backups it will grab the next available<br>
drive. <br>
<br>
<br>
-----Original Message-----<br>
From: veritas-bu-request AT mailman.eng.auburn DOT edu<br>
[mailto:veritas-bu-request AT mailman.eng.auburn DOT edu] <br>
Sent: Wednesday, September 10, 2003 1:02 PM<br>
To: veritas-bu AT mailman.eng.auburn DOT edu<br>
Subject: Veritas-bu digest, Vol 1 #2498 - 1 msg<br>
<br>
<br>
Send Veritas-bu mailing list submissions to<br>
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When replying, please edit your Subject line so it is more specific than<br>
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<br>
<br>
Today's Topics:<br>
<br>
 &nbsp; 1. Re: Prioritizing Restores over Backups in 4.5 (Wayne T Smith)<br>
<br>
--__--__--<br>
<br>
Message: 1<br>
Date: Wed, 10 Sep 2003 09:38:34 -0400<br>
From: Wayne T Smith &lt;WTSmith AT maine DOT edu&gt;<br>
To: veritas-bu AT mailman.eng.auburn DOT edu<br>
Subject: Re: [Veritas-bu] Prioritizing Restores over Backups in 4.5<br>
<br>
Hart, Charles wrote, in part:<br>
<br>
&gt; Oh.. I can't hold it in. &nbsp;I'm a fairly new user to Netbackup 4.5FP#, 
<br>
&gt; have been using TSM for a couple years, and I find this troubling. 
&nbsp;In<br>
the TSM world Restores Always take precedence. &nbsp;If another task is 
using<br>
a drive in TSM, TSM will make a drive available, then once the restore<br>
is complete TSM will know where it left off on the prior task.<br>
&gt; <br>
&gt; I feel like I've just traded in my Cadillac for a KIA.....<br>
<br>
You did! &nbsp;Join the club. &nbsp;Nothing is perfect, though that Cadillac 
was <br>
pretty good. &nbsp;;-)<br>
<br>
cheers, wayne<br>
<br>
<br>
<br>
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