Re: [9fans] Help with two small shared file servers

[John Floren <john@jfloren.net>]

On Wed, Aug 17, 2011 at 2:00 PM, Bakul Shah <bakul@bitblocks.com> wrote:
> On Wed, 17 Aug 2011 13:09:47 +0300 =?UTF-8?B?QXJhbSBIxIN2xINybmVhbnU=?= <aram.h@mgk.ro>  wrote:
>> Hello,
>>
>> I'm looking for advice on how to build a small network of two file
>> servers. I'm hoping most servers to be Plan9, clients are Windows and
>> Mac OS X.
>>
>> I have 2 houses separated by about 40ms of network latency. I want to
>> set some servers in each location and have all data accessible from
>> anywhere. I'll have about 2TB of data at each location, one location
>> will probably scale up.
>        ...
>> Is 9p suitable for this? How will the 40ms latency affect 9p
>> operation? (I have 100Mbit).
>
> With a strict request/response protocol you will get no more
> than 64KB once every 80ms so your throughput at best will be
> 6.55Mbps or about 15 times slower than using HTTP/FTP on
> 100Mbps link for large files.  [John, what was the link speed
> for the tests in your thesis?]
>

10 Mbps was the bottleneck--I had a 100 Mbit switch connected to one
side of the Linux gateway and a 10 Mbit hub on the other. I know a 10
Mbit hub is not modern networking equipment, but the only traffic on
it was the tests, and I also figured that 1. You're not likely to do
much better on a cross-country net link anyway, and 2. The HTTP tests
would suffer just as badly :)

If you'd like to Dare to Be Stupid, you can download my source and run
both servers with streaming enabled, then make some sort of
client-side caching filesystem which can stream from the remote (40 ms
away) server on behalf of applications, avoiding the necessity of
re-coding all your applications to understand streaming.

Or just serve your files over SMB, NFS, or HTTP.

I guess I didn't check, but if you *have* 2 TB of data but don't plan
to routinely *access* that much of it at any given time, you can
probably get away with using 9P.

I do not think there is any way a fossil+venti or kenfs file server
serving 9P will outperform your Solaris server. Not with our current
software. The way I use it, Plan 9 and 9P are "fast enough", but for
serious data transfer over such a high-latency link they won't cut it.
Plan 9 + HTTP would be a reasonable option if you just want to share
movies and music between your houses, I suppose.


John