[volunteergrid2-l] upload speeds

[erpo41 at gmail.com]

On Thu, Apr 12, 2012 at 9:00 PM, Shawn Willden <shawn at willden.org> wrote:

> On Thu, Apr 12, 2012 at 8:09 PM, erpo41 at gmail.com <erpo41 at gmail.com>wrote:
>
>>
>>>> *I don't think it's my upstream connection since I have about 1000Kbps
>> upstream capacity and I'm not using it for anything else.
>> *I don't think it's everyone else's downstream connection because those
>> are typically way faster than 200Kbps.
>>
>
> Do you mean Kbps or KBps (bits or bytes)?  If your upstream is 1000 Kbps
> or 1 Mbps, then your max upload speed would be about 100 KBps, so I'm
> assuming you must mean KBps.
>

I mean 200,000 bits per second.


> Terminology quibble out of the way, the Tahoe uploader is somewhat stupid,
> as I understand it, and effectively limits your upload speed to that of the
> slowest node, and then limits it some more due to inter-message waiting
> delays.
>

That might explain it. Based on the error messages I've seen so far, I
suspect that the tahoe CLI goes through the WUI doing one PUT request at a
time. That PUT request shouldn't return until the file is totally uploaded
including all erasure coding data to all servers, so it would make sense
that the slowest node would place a lower limit on the transfer time.


> I'm currently sustaining about 3.3 Mbps upload rate (measured at the NIC)
> which translates to net upload speeds (reported by Tahoe) of around 230
> KBps.  Since I'm using N=19, K=11, my expansion factor is 1.72, which turns
> 230 KBps into 396 KBps, which is 3164 Kbps.
>

My 200Kbps is measured at the NIC also. How do I pull stats out of tahoe
directly?


> That's far below my maximum upstream speed (~50 Mbps),
>

Braggart. :)


> but if I can sustain 200 KBps, I can upload 17 GB per day, which is
> perfectly adequate for my needs.
>

Hey, 200Kbps meets my needs just fine; it's more bandwidth to offsite
backup than I had before I joined the grid. But if I can get more I'd like
it.


> My bigger problem is that with N=19 and only 20 nodes accepting shares
> even when everything is up, my uploads tend to get stopped a lot.
>
>
This is why I picked N=15, H=10, K=5. So far, no issues in that area.

Thanks,
Eric
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