[OpenAFS] Questions regarding `afsd` caching arguments (`-dcache` and `-files`)

Mark Vitale mvitale@sinenomine.net
Fri, 8 Mar 2019 19:58:14 +0000

> On Mar 8, 2019, at 2:38 PM, Ciprian Dorin Craciun <ciprian.craciun@gmail.=
com> wrote:
> On Fri, Mar 8, 2019 at 9:30 PM Mark Vitale <mvitale@sinenomine.net> wrote=
>> But now on more careful reading, I see this only applies when -dcache ha=
s not been explicitly specified.
>> (Which, to be fair, is the normal case).
> Thanks for the insight.
>>> (I'm struggling to get AFS to go over the 50MB/s, i.e. half a GigaBit,
>>> bandwidth...  My target is to saturate a full GigaBit link...)
>> Here are some helpful commands for examining the results of your configu=
ration experiments:
>> cmdebug <client> -cache
>> fs getcacheparms -excessive
> Perhaps you know:  what is the maximum bandwidth that one has achieved
> with OpenAFS?  (Not a "record" but in the sense "usually in enterprise
> deployments we see zzz MB/s".)

I think this may be a question like "how long is a piece of string?".
The answer is "it depends".  Could you be more specific about your use case=
and what you are seeing (or need to see) in terms of OpenAFS performance?

> (I think my issue is with the file-server not the cache-manager...)

It is easy to get bottlenecks on both.  One way to help characterize this
is to use some of the OpenAFS test programs and see how they perform agains=
t your fileservers:
- afscp  (tests/afscp)
- afsio  (src/venus/afsio)

There is also the test server/client pair for checking raw rx network throu=
- rxperf  (src/tools/rxperf)

Mark Vitale