[Samba] [questions] aio settings in smb.conf and compile options

[Jeremy Allison]

On Tue, Aug 01, 2006 at 09:17:04AM +0200, Michael Gasch wrote:
> hi,
> 
> i just have some questions about specific (uncommon) compile options and 
> aio-settings in smb.conf:
> 
> Asynchronous IO Support
> =======================
> 
> "Experimental support for async IO has been added to smbd for
> certain platforms.  To enable this new feature, Samba must be
> compiled to include the --with-aio-support configure option.
> In addition, the "aio read size" and "aio write size" to non-zero
> values.  See the smb.conf(5) man page for more details on these
> settings.
> 
> unfortunately i can´t find any documentation about this although it has 
> been in the code since a while."

Compile with --with-aio-support to enable this. Look in the source
code smbd/aio.c. I haven't documented the parameters yet (thanks
for the reminder, I'll try and get this done soon). They are :

aio read size = <bytes>
aio write size = <bytes>
aio write behind = <true|false>

Any reads/writes over <bytes> will be done via aio. It hasn't
been turned on fully yet as some Linux's fake aio support using
pthreads which makes smbd *slower* :-(. Kernel support for aio
is still a little flakey - I need to spend some more time testing
it. The biggest disappointment is that there seems to be no way
to get Windows clients to pipeline more than one read or write
on the wire. They simply stick with a request/response pair.
smbclient will pipeline reads/writes though. Not sure about
cifsfs - Stevef, any comments (or I'll just go look in the 
code :-).

aio write behind was an attempt to see if we could fool Windows
clients into pipelining. If set true, smbd *lies* about writes
being done (and assumes the aio will always succeed) and returns
early "success" to the client. Don't set this if you have *any*
interest in your data :-).

> Compile Options - what means/provides (more detailed please) ... ?
> ==================================================================
> --with-cluster-support
> --with-automount

Volker knows more about these.

> BIG THX!!!!!!
> 
> btw: what happened to john? is he still an active member of the samba 
> team, ´cause i did not see any posts on the list for example?!?!

John is now working at AMD, who keep him rather busy on his day
job :-). He still wants to keep active but it's easier said than
done :-).

Jeremy.