[Dovecot] SSD drives are really fast running Dovecot

[Brandon Davidson]

Stan,

On 1/14/11 7:09 PM, "Stan Hoeppner" <stan at hardwarefreak.com> wrote:
> 
> The average size of an email worldwide today is less than 4KB, less than one
> typical filesystem block.
> 
> 28TB / 4KB = 28,000,000,000,000 bytes / 4096 bytes = 6,835,937,500 =
> 6.8 billion emails / 5,000 users =
> 1,367,188 emails per user
> 
> 6.8 billion emails is "not much anymore" for a 5,000 seat org?

You obviously don't live in the same world I do. Have you ever been part of
a grant approval process and seen what kinds of files are exchanged, and
with what frequency? Complied with retention and archival policies? Dealt
with folks who won't (or can't) delete an message once they've received it?

Blithely applying some inexplicable figure you've pulled out of
who-knows-where and extrapolating from that hardly constitutes prudent
planning. We based our requirement on real numbers observed in our
environment, expected growth, and our budget cycle. How do you plan? More
blind averaging?

> How much did that 252TB NetApp cost the university?  $300k?  $700k?  Just a
> drop
> in the bucket right?  Do you think that was a smart purchasing decision, given
> your state's $3.8 Billion deficit?

You're close, if a bit high with one of your guesses. Netapp is good to
Education. Not that it matters - you know very little about the financial
state of my institution or how capital expenditures work within my
department's funding model.

I suppose I shouldn't be surprised though, you seem to be very skilled at
taking a little bit of information and making a convincing-sounding argument
about it... regardless of how much you actually know.

> For comparison, as of Feb 2009, the entire digital online content of the
> Library
> of Congress was only 74TB.  And you just purchased 252TB just for email for a
> 5,000 head count subsection of a small state university's population?

I work for central IS, so this is the first stage of a consolidated service
offering that we anticipate may encompass all of our staff and faculty. We
bought what we could with what we had, anticipating that usage will grow
over time as individual units migrate off their existing infrastructure.
Again, you're guessing and casting aspersions.

This is enterprise storage; I'm not sure that you know what this actually
means either. With Netapp you generally lose on the order of 35-45% due to
right-sizing, RAID, spares, and aggregate/volume/snapshot reserves. What's
left will be carved up into LUNs and presented to the hosts.

1/3 of the available capacity is passive 3rd-site disaster-recovery. The
remaining 2 sites each host both an active and a passive copy of each mail
store; we design to be able to sustain a site outage without loss of
service. Each site has extra space for several years of growth, database
restores, and archival / records retention reserves.

That's how 16TB of active mail can end up requiring 252TB of raw disk. Doing
things right can be expensive, but it's usually cheaper in the long run than
doing it wrong. It's like looking into a whole other world for you, isn't
it? No Newegg parts here...

-Brad