Veritas-bu

Re: [Veritas-bu] How do you report on utilization?

2008-07-30 20:37:08
Subject: Re: [Veritas-bu] How do you report on utilization?
From: "Ed Wilts" <ewilts AT ewilts DOT org>
To: "Brian J. Greenberg" <bjgreenberg AT gmail DOT com>
Date: Wed, 30 Jul 2008 19:16:37 -0500
On Wed, Jul 30, 2008 at 5:16 PM, Brian J. Greenberg <bjgreenberg AT gmail DOT com> wrote:
For all of you doing heavy reporting on NBU, I've discovered an inconsistency about how NBU reports job information between bpdbjobs and bpimagelist.


I'm told by Symantec that the reasons for the discrepencies between bpdbjobs and bpimagelist numbers for NDMP based backups seems to be in the fact that NDMP is doing block based calculations and providing block sizes back to bpdbjobs and somehow bpimagelist is getting correct file based calculations when the job is complete. 

Regardless as to why this occurs, the fact of the matter is that the numbers are different and they shouldn't be,

I'm not sure they shouldn't be different.  If you're backing up different stuff with NDMP vs non-NDMP, shouldn't you be charging differently?  How about if you use FlashBackups?  Do you want to charge back for the empty blocks you're now backing up?  If you're not charging the customer, should you be eating the cost?  What if you're doing de-dupe to disk?  Should the customer be paying for what they're actually backing up or for what they're actually consuming on disk?  And then if customer A deletes a file and now customer B pays the full shot, is that fair?  Is it fair to charge both of them for the same backup disk block?  What if you had 1,000 customers all paying for backing up the same copies of Windows and are de-duping that?  Should you charge each one of them?

Chargeback is an ugly, ugly problem and the technology you use shouldn't really have an impact on how you're charging back, but of course it does. 

If you're backing up 3 4K blocks for a 9K file, do you want to charge the customer for 12K or 9K?  After all, they're really consuming 12K on disk.  Do you charge them for the disk blocks or the space they're actually using?  If you're only charging them for the space they're using, you're losing money - the customer paying for 9K isn't paying enough, since you can't bill the other 3K to somebody else.

Simply put, there is no right answer here.  All answers suck for different reasons.   You can spend more time justifying the chargeback algorithms and trying to figure out how to do the chargeback than it's worth.  I've seen one case where we spent a ton of time working on internal chargebacks but it made absolutely no difference in the end as to how the money was spent.  If we needed more capacity, we had to buy it anyway.  We turned chargeback off.
 
especially when considering that most organizations and service providers are charging back and/or generating revenue from the data that most reporting engines seems to be collecting from bpdbjobs and not bpimagelist.

Most organizations don't actually charge back to that level of detail.  And the reason they don't is because all chargeback algorithms suck.
.../Ed

Ed Wilts, RHCE, BCFP, BCSD, SCSP, SCSE
ewilts AT ewilts DOT org
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