[Dovecot] SSD drives are really fast running Dovecot

[Stan Hoeppner]

Brandon Davidson put forth on 1/14/2011 10:59 PM:

> You obviously don't live in the same world I do. Have you ever been part of

Not currently, no, thankfully.

> a grant approval process and seen what kinds of files are exchanged, and

I've never worked in the public sector, only private, so I've not dealt with the
grant process, but I'm not totally ignorant of them either.  I've assisted a
couple of colleagues in the past with grant proposals.  And yes, they can, and
often do, suck.

> 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?

I have, unfortunately, had to deal with regulatory compliance and some of the
less than sane communications retention policies.

> Blithely applying some inexplicable figure you've pulled out of
> who-knows-where and extrapolating from that hardly constitutes prudent
> planning. 

Statistics are guidelines.  As I'm not planning anything in this thread, I don't
see how such non existent planning could be categorized as prudent or not.  What
I did do is simply make the case that 252TB seems bleeping outrageously high for
5k users, whether that entails email alone or every other kind of storage those
5k users need.  If my math is correct, that's about 50GB/user, including your
snapshot LUNs, etc.

> We based our requirement on real numbers observed in our
> environment, expected growth, and our budget cycle. 

You forgot to mention the 35-45% (mentioned below) gross storage loss due to
inefficiencies in your chosen hardware vendor's platform/architecture.  Over a
third and almost half of the drive cost is entangled here is it not?

> How do you plan? More
> blind averaging?

Ouija board.

> You're close, if a bit high with one of your guesses. Netapp is good to
> Education. 

Vendors with the largest profit margins (read: over priced) built into their
products are those most willing and able to give big discounts to select customers.

> 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.

That's true.  I know nothing about the financial state of your institution.  I
didn't claim to.  I simply know Oregon was/is facing a $3.8B deficit.  Your
institution is part of the state government budget.  Thus, your institution's
spending is part of that budget/deficit.  That's simply fact.  No?

> 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.

I know this:  252TB is bleeping ridiculously large for 5K seats at _any_
university, public or private, regardless of how much is wasted for "data
management".  Also, 34%-45% consumption of raw for any internal array
functions/management is bleeping ridiculous.  Is that your definition of
"enterprise"?  Massive required waste of raw capacity?

> 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.

Guessing?  Originally you stated that 252TB for email only, or specifically
Exchange.  You said nothing of a mass storage consolidation project:

Brad Davidson put forth on 1/14/2011 6:25 PM:

> We just bought 252TB of raw disk for about 5k users. Given, this is
> going in to Exchange on Netapp


Casting aspersions?  aspersion:

a : a false or misleading charge meant to harm someone's reputation <cast
aspersions on her integrity>

What false or misleading charge did I make with the intention to harm your
reputation Brad?  I've merely made a technical argument for sane email retention
policies, and against the need for 252TB for 5K users' email.  I don't recall
casting any 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.

If your definition of "enterprise storage" is losing 34-45% of raw capacity for
housekeeping chores, then I'll stick with my definition, and with Nexsan for my
"enterprise" storage needs.

You didn't mention deduplication once yet.  With Nexsan's DeDupe SG I cut my
regulatory dictated on disk storage requirements in half, and Nexsan disk costs
half as much as NetApp, for the same SATA disks.  With Nexsan, my overall
storage costs are less than half of a NetApp, for basically the same capability.
 The only "downside" is that I can't get all of the functionality in a single
head controller--however in many ways this is actually an advantage.  My total
costs are still far lower than going with an FAS, CLARiiON, or HNAS+HCP.  All
software is integrated with no additional licensing costs.  I have no
restrictions on the number of SAN or CFS/CIFS hosts I can connect to a LUN or an
exported filesystem.

Don't get me wrong--NetApp, EMC, and HDS all make great products with nice
capabilities.  However, you _really_ pay through the nose for it, and keep
paying for it as you needs grow.  With Nexsan I pay once and only once,
unless/until I need more disks.  No additional fees to unlock any capabilities
already in the box.  No restrictions.

> 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.

Ok, so this 252TB of disk is actually spread out over multiple buildings with
multiple FAS controllers, one in each building?  And this 252TB isn't just for
mail (and its safeguard data) as you previously stated?

> 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...

There are many ways to "do things right".  And I'd humbly suggest ballooning
16TB of mail (again ridiculously large) into 252TB of raw disk (you're still
confusing us as to what is actually what in that 252TB) is not one of them.
That's a 16x increase.  Do you have deduplication and compression installed,
enabled, and scheduled?

-- 
Stan