[Asterisk-Users] drive space for voice mail

[Steven Critchfield]

On Fri, 2004-12-03 at 11:05 +1100, Adam Hart wrote:
> Christopher L. Wade wrote:
> 
> > Matthew Boehm wrote:
> > 
> >> Can you say 'overkill' ?  *smiles*
> >>
> >> I just recorded a 2min voicemail and the resulting file on the server was
> >> slightly over 200KB in size.
> >> We are only storing 1 format of soundfiles, WAV49.
> >>
> >> A 160GB drive is approx 1,677,721,160 KB.
> >>
> >> At the rate above you would be able to store almost 28,000 hours of
> >> voicemail messages.
> >>
> >> Someone wanna check my math?
> > 
> > 
> > Unless my recent math [280,000 hours] was wrong, thats ~ 31 years of 
> > voicemail :)
> > 
> 
> Better get 200GB just to be safe :p

Only downside is while you may be scratching your heads making sure the
numbers presented are properly computed, I didn't see anyone verify the
numbers being used.

First your number above is off by a bunch. 160*1024*1024 only has 2 1's,
or just 167,772,160 kb.

Second, how many bytes available depends on the manufacturer. Seagate's
sales lit actually specify 10^9, or exactly 1,000,000,000. Same for
Maxtor. Same for WD. I'm giving up searching for any that define a gb as
2^30 like we would expect and the number above actually is based on.

So 160gb is only 160,000,000,000 bytes or 149gb of gb=2^30. 

If you consider the WAV49 header to be nearly nothing in the total space
of the file, WAV49 or MS-GSM coding puts 40ms of audio per 65 bytes or
1625 bytes per second.

Now, so barring any filesystem questions, the raw capacity could only
hold 27,350 hours.
(160,000,000,000)/1625 bytes per second /60 seconds per minute /60
minutes per hour = 27,350 hours.

Don't forget you lose space when you format the drive. Also remember
that under ext2/3 that you are likely to have 4k blocks. While at it
isn't much to lose 2-3k of space for each file when you are talking
about many k of space per file, it adds up after a while.

So in the end, expect that a 160gb drive is only likely to store 27,000
hours of WAV49 recordings if it is the only thing the drive is being
used for.
-- 
Steven Critchfield <critch at basesys.com>