[tahoe-dev] the provisioning tool in tahoe

[Brian Warner]

> On Thu, Dec 8, 2011 at 8:24 PM, Brian Warner <warner at lothar.com> wrote:

>> I'll incorporate your patch when I do that code-surgery.

Take a look at:

 https://github.com/warner/tahoe-lafs/tree/deprovisioning

in the misc/operations_helpers/provisioning/ directory. Run "run.py" in
that directory, and it should pop open a browser with both tools. I've
removed the tools from their old place (and updated the tests).

Jimmy: if you could review that and let me know if that works for you,
I'll land it on trunk later this week.

> cool, I was also wondering if the MTBF needs some updating as well,
> the current value seems to be based of an old google publication which
> I couldn't find (if anyone can share it, it would be great).

I think this is what I based it on:

 http://storagemojo.com/2007/02/19/googles-disk-failure-experience/
 http://www.usenix.org/event/fast07/tech/full_papers/pinheiro/pinheiro_html/
 http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.163.4740

> I think having a few 'standard' MTBF's that manufacturers appear to be
> selling drives at might be worth putting in as user selectable values
> as well.

Yeah! It's a pity that there are so few useful statistics and studies
out there. Very few of the players who could do the research have an
incentive to be honest about the results :).

> BTW I'm finding the provisioning tool to be fairly useful outside of
> tahoe for estimating sizes and costs for a storage system :P

Great!

One thing I'd keep in mind, the "average space consumed per user" in a
real deployment is (hopefully!) likely to be much much less than the
space given to each user. My Dropbox client tells me that I'm only using
13% of my 2.0GB quota, and they're absolutely depending upon most users
being like me: if everyone used their full quota, they'd go out of
business even faster :). So measuring real-world usage, given a certain
user demographic and use patterns, is pretty important for real
provisioning work.


thanks!
 -Brian