The formula is on pg 163 of the 3.4 SAG.  

Basically, you need to know how many files you're going to backup and how
many copies of each you'll have (retention / frequency).  Multiply
that by the length of the pathname plus some overhead for username,
perms, etc (150 is a decent average).

So, if you were doing a cold backup of 27 raw devices once a week kept
for 8 weeks, you'd need something like:

(27 files * 8 copies * 150 bytes/(file*copy)) = 32.4 KB.

Now, if you were using a db extension, you may or may not have 27
"files", often you'd have one "file" per table.

As you can see, the amount of data you're backing up has nothing to do
with the amount of catalog space required.  It's the amount of FILES,
since that's what gets tracked.

Simon, Leonard writes:
> Question for all:
> 
> We currently have a requirement to back up a 12TB RAW sybase IQ with 27 luns
> every week
> and need to  figure out how large our NBU databases are going to grow
> with this new requirement. Does anyone have a formula, or even an idea on
> how much space will be
> required in the databases for this RAW backup?
> 
> Thanks,
> Lenny Simon
> Nielsen Media Research
> 
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-- 
Larry Kingery 
         "That rabbit's got a vicious streak. It's a killer!"