Veritas-bu

[Veritas-bu] Yet another bpstart/bpend script question

2007-01-23 05:01:39
Subject: [Veritas-bu] Yet another bpstart/bpend script question
From: Philip.Weber at egg.com (Weber, Philip)
Date: Tue, 23 Jan 2007 10:01:39 -0000
I spent some time on this a year or two ago for backing up Oracle
without using the NetBackup Agent.  I found

1.  Do the "start of backup" work on the first stream that runs, which
isn't necessarily STREAM_NUMBER=1.  Set a flag to indicate it's
complete.  You'll have to do some checking to prevent two "first"
streams locking each other out.
2.  1st stream that runs should create lock files for all the expected
streams, using STREAM_COUNT, which each subsequent stream removes when
complete.  Otherwise, in a busy environment, some streams could complete
and none be running, the database get started back up, before some of
the streams have even begun.

There may be other things to address, I still get the occasional failure
but they have been infrequent enough not to merit any further work on
this yet.

Hope this helps,
Phil

> -----Original Message-----
> From: veritas-bu-bounces at mailman.eng.auburn.edu 
> [mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf 
> Of Ellis, Jason
> Sent: 19 January 2007 16:49
> To: Ed Wilts
> Cc: veritas-bu at mailman.eng.auburn.edu
> Subject: Re: [Veritas-bu] Yet another bpstart/bpend script question
> 
> 
> Actually I plan to create .lock files for each stream as they call the
> bpstart_notify script. For example:
> 
> Stream 1 starts and creates the stream_1.lock file.
> 
> Stream 2 starts and creates the stream_2.lock file.
> 
> Stream 3 starts and creates the stream_3.lock file.
> 
> Later:
> 
> Stream 2 completes and deletes its .lock file, but the bpend_notify
> script still finds the .lock file for stream 1 and 3.
> 
> Stream 1 completes and deletes its .lock file, but the bpend_notify
> script still finds the .lock file for stream 3.
> 
> Finally stream 3 completes and deletes its .lock file. The 
> bpend_notify
> script, not finding any more .lock files, runs the final tasks and
> completes.
> 
> In theory this should work.
> 
> Jason Ellis
> Technical Consultant, Data Protection Team
> IndyMac Bank, La Mirada Datacenter
> Phone: (714) 520-3414
> Mobile: (714) 889-8734
> 
> -----Original Message-----
> From: Ed Wilts [mailto:ewilts at ewilts.org] 
> Sent: Thursday, January 18, 2007 7:42 PM
> To: Ellis, Jason
> Cc: veritas-bu at mailman.eng.auburn.edu
> Subject: Re: [Veritas-bu] Yet another bpstart/bpend script question
> 
> On 1/18/2007 6:25 PM, Ellis, Jason wrote:
> > I really need to capture the STREAM_NUMBER if possible to help
> mitigate 
> > a job with multiple data streams. My idea is to use lock files to 
> > prevent the bpstart_notify from running once one stream has already 
> > started, and the bpend_notify script from kicking off until 
> the last 
> > stream has completed.
> 
> This is a lost cause so save yourself some work.  There is no 
> guarantee 
> that the last stream won't complete before an earlier stream 
> and unless 
> you disallow retries completely, the task gets harder and harders.
> 
> What are you going to do if stream 1 starts, gets partially 
> done, has a 
> tape error, and retries?  What are you going to do if the last stream 
> finishes early?  What are you going to do if the last stream dies 
> completely and can't finish?
> 
> The problem is much harder than it looks...
> 
>       .../Ed
> 
> -- 
> Ed Wilts, Mounds View, MN, USA
> mailto:ewilts at ewilts.org
> 
> 
> 
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> 

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