Folks,

Thanks a lot for your comments and advises. Ed, especially thank you for 
your detailed info! Very useful.

regards,

Darek


Ed Wilts wrote:
> On Fri, Mar 28, 2008 at 8:03 AM, Dariusz Klar <Dariusz.Klar AT sun DOT com 
> <mailto:Dariusz.Klar AT sun DOT com>> wrote:
>
>     I know the general rules, but... Another challenge for me is to
>     estimate
>     disk space for NetBackup catalog where total amount of data under
>     NetBackup protection is 3.6 PB (peta bytes) with ability to grow
>     to 8.5
>     PB in the future.
>
>
> Yes, size matters.  but if that 3.6PB consists of 10k tiff files (and 
> I would feel your pain!), your catalog would be significantly larger 
> than if it consists of 100GB Oracle tables.
>  
>
>     The difference between 1% and 2% of total amount of protected data for
>     catalog does matter. The difference vary from 36 TB to 85 TB in
>     case of
>     1% difference. I need to be more precise. If I will say to my customer
>     that they have to buy 255 TB (3% of total amount of data in the
>     future)
>     for NetBackup catalog, I have to be 100% sure what I'm talking about.
>
>     I called Symantec and with that big data volume they are not 100% sure
>     about space size for NetBackup catalog.
>
>
> Data volume does not matter - the number of unique filenames does.  I 
> could design the application to put 100 files in 100 directories and 
> end up with a much larger catalog than if I put those 10,000 files in 
> a single directory.
>
> If the data is all transitory and your retentions are long, the 
> catalog will be much larger than if the data was fairly stagnant or 
> retentions short.  My Exchange environment is about 3TB or so and my 
> catalog for that is about 2.2MB - that's under 0.01%.  I have about 
> the same amount of disk space in an environment that has host-based 
> mirror sets, longer retentions, more transitory data, and small 
> files.  The catalog for that is 25GB - 1,000 times larger for the same 
> amount of disk space.  Even that is only 0.8% of allocated disk 
> space.  I have a 27TB application that requires 147GB of catalog space 
> - about 0.5% - and it too has lots of little files.
>
> My total catalog size is under 600GB and we have about a 340GB of 
> allocated disk space (that's SAN based and doesn't count the servers 
> with local disk space or volumes that have host-based mirrors).  
> That's about 0.2% of allocated space, nowhere near the 1-3% that 
> you've been looking at.  Again, how you use and back up your data will 
> have a very significant impact on your catalog size.
>
> If your customer can tell you exactly how they're going to use the 
> disk space and what their backup policies and retentions are going to 
> be, then you can be more accurate in calculating a catalog size.  If 
> they can't, you're not going to have enough information to make a 
> useful prediction.
>


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