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List:       linux-dump-users
Subject:    Re: [Dump-users] Solved: Problems spanning tapes with dump (summary)
From:       Tom Haws <trh () timberline ! ca>
Date:       2003-11-21 19:36:43
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Mike Castle wrote:

>On Fri, Nov 21, 2003 at 10:29:33AM -0800, Tom Haws wrote:
>  
>
>>detected by dump, it calls the script, which does an rsh back to the 
>>host with the tapedrive, rewinds the tape there (causing our autochanger 
>>in sequential mode to load the next tape), sleeps a couple of minutes, 
>>then exits with a return code of zero.  This allows dump to resume, 
>>without trying to contact anyone, and all is fine.
>>    
>>
>
>
>A 'sleep 2 minutes' approach always scares me.  No matter how long you make
>the delay, sometime there is going to be a case where it's not long enough
>and things will crash.
>
>Would a better solution be to make use of mt status on the drive
>periodically and when it's done changing the tape, exit?   By making the
>call to mt status something like every 10 seconds, you might actually
>return in less than 2 minutes in most cases, and increase throughput!  :->
>
>Obviously you'd want to put limits on how many times you run mt status so
>you can detect that things went really bad.
>
>mrc
>
Yeah, I know what you mean with a sleep.  One day, it just won't be 
enough.  One good thing is that the "mt -t rewoffl" does not return 
until the tape is rewound and the next one is loaded (the autochanger 
hardware must not release the command until it obeys the sequential mode 
programming in it?), and my sleep comes after that, so it's kind of like 
insurance.

I like your idea of doing some checking, and I might incorporate that in 
the future, but for now, I'm just so relieved to get a backup that I 
don't want to touch it!

-Tom

-- 
_______________________________________________________________________
Tom Haws               Manager, Systems Administration
trh@timberline.ca      Timberline Forest Inventory Consultants
Tel: (250) 562-2628    1579 9th Ave, Prince George, B.C. Canada V2L 3R8
Fax: (250) 562-6942    http://www.timberline.ca
_______________________________________________________________________





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