Veritas-bu

[Veritas-bu] Frequency based versus calendar based

2006-06-13 15:48:58
Subject: [Veritas-bu] Frequency based versus calendar based
From: wts at maine.edu (Wayne T Smith)
Date: Tue, 13 Jun 2006 15:48:58 -0400
Calendar-based scheduling was better once I got to a certain level of 
understanding. 

Pros:

A good benefit was being able to add a client to a policy and, like 
magic, a full backup is done that evening, even though 98% of my fulls 
are done on a weekend.

Like many, I have a weekly full backup with one retention, and a less 
frequent, full backup that is retained longer.  This meant that each 
weekend I'd have some of one kind of backup and some of another.  Since 
I have one retention level per tape, this meant  I'd frequently have a 
slow, long retention backup "hogging" a tape drive when other backups 
were playing nicely at my multiplexing limit.  On bad days, I'd have 2 
or 3 of these slow backups start on different tapes, really putting a 
crimp into the works (I only have 5 drives and they are busy 90+% of the 
time).  Calendar-based scheduling has allowed me to minimize this.  Now, 
all my (monthly) long-retention backups are done during the first week 
of the month.  I may want to watch that first week, but in general the 
calendar-based schedules run without any babysitting.

Also, for those clients that allow it, the "allow retry after run day" 
really helps NetBackup keep backups going so I don't have to babysit so 
much.  In my experience, I have more complete backups with this setting 
and that means better ability to restore.

Add a periodic "endangered filesets" report (courtesy of someone on this 
mailing list) and I now consider NetBackup (v5.1MP5) worthy of its 
"Enterprise" title, something I would not have said before (this report 
and calendar-based scheduling)!

Some have complained about before and after midnight being different 
days, with problems or unexpected results with a window that spans 
midnight.  Frequency-based schedules share some of these problems, so 
some time ago I just split up my workload so some backups are kicked off 
before midnight and some after.    Setup well, I get few 196s (backup 
didn't start in window), and most of them are not at midnight, but at 4 
or 5 in the morning when something strange happened to delay everything.

Cons:

Relative to frequency-based scheduling, calendar-based schedules have no 
cons.   If I hadn't started with frequency-based schedules in NetBackup, 
I'd say frequency-based is weird and goofy.  What? You mean I pick a 
4-day frequency for weekly backups?  Now that is goofy.  ;-)

cheers, wayne

Hindle, Greg wrote, in part,  on 6/13/2006 2:36 PM:
>
> What are the pros and cons of each?
>
>
> We have switched from calendar base to frequency based but there are 
> rumblings about switching back. I need more info to keep this from 
> happening. I have copies down ideas from the current discussion but 
> thought their has to be more reason why frequency based is better than 
> calendar based? Right?
>
>
> Greg
>
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