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

[Michael Gasch]

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

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?!?!
--
Michael Gasch
Max Planck Institute for Evolutionary Anthropology
Department of Human Evolution (IT Staff)
Deutscher Platz 6
D-04103 Leipzig
Germany

Phone: 49 (0)341 - 3550 137
49 (0)341 - 3550 374

Fax: 49 (0)341 - 3550 399

[Volker Lendecke]

Post by Michael Gasch
--with-cluster-support

That's an option to later enable all cluster features that
we're working on. If you are interested in the current (VERY
experimental) state of affairs look at the vl-messaging
temporary svn branch.

The idea is that with a clustered file system like GFS,
OCFS, GPFS or some others you will be able to share the same
file space transparently from all cluster nodes and have
locking working properly. Right now we are discussing and
designing ways to make the experimental support for that
robust so that we don't depend on a single point of failure.

Volker
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[Jeremy Allison]

Post by Michael Gasch
hi,
i just have some questions about specific (uncommon) compile options and
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 :-).

Post by Michael Gasch
Compile Options - what means/provides (more detailed please) ... ?
==================================================================
--with-cluster-support
--with-automount

Volker knows more about these.

Post by Michael Gasch
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.

[Michael Gasch]

thx to jeremy and volker for your quick and detailed response (as usual)...

if someone has any explanation for "--with-automount" i would appreciate
this as well :)

i'm just trying to explore samba features i recognized but often can't
interpret there meaning.

@jeremy
looks like you took over john's part since you seem to be more present
on the list than before :-D (could be too much imagition, though)


cheerz

[simo]

IIRC --with-automount should automount the home directory when a user
steps in.

Simo.

Post by Michael Gasch
thx to jeremy and volker for your quick and detailed response (as usual)...
if someone has any explanation for "--with-automount" i would appreciate
this as well :)
i'm just trying to explore samba features i recognized but often can't
interpret there meaning.
@jeremy
looks like you took over john's part since you seem to be more present
on the list than before :-D (could be too much imagition, though)
cheerz

[Volker Lendecke]

Post by simo
IIRC --with-automount should automount the home directory when a user
steps in.

I'm afraid, this is not what it does. man smb.conf says

%N the name of your NIS home directory server. This
is obtained from your NIS auto.map entry. If you
have not compiled Samba with the --with-automount
option then this value will be the same as %.

Looking at the code it also needs the undocumented parameter
'nis home map' to be true.

Volker
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[simo]

Post by Volker Lendecke

Post by simo
IIRC --with-automount should automount the home directory when a user
steps in.

I'm afraid, this is not what it does. man smb.conf says
%N the name of your NIS home directory server. This
is obtained from your NIS auto.map entry. If you
have not compiled Samba with the --with-automount
option then this value will be the same as %.
Looking at the code it also needs the undocumented parameter
'nis home map' to be true.

Right,
reading the code it also looks up where your NIS home directory is using
yp calls when %p is used.

This configure option name is really misleading imo.
Simo.

[Jeremy Allison]

Post by Michael Gasch
@jeremy
looks like you took over john's part since you seem to be more present
on the list than before :-D (could be too much imagition, though)

Nah, no one can replace John :-). I'm just trying to keep answering
questions as usual (modulo working for a living :-).

Jeremy.