[Samba] Configuring aio_pthread

[Jeremy Allison]

On Wed, Sep 10, 2014 at 09:30:24AM -0500, Andrew Walker wrote:
> I'm trying to learn more about samba by experimenting with samba on
> FreeNAS. This involves a certain amount of reading how default smb4.conf
> parameters are set in FreeNAS and then reading the manpages for those
> parameters.

Exactly what Samba version is being shipped ?

> Async I/O is implemented in samba in freenas via the aio_pthread VFS
> module. The manpage for vfs_aio_pthread states:
> "the smb.conf parameters aio read size and aio write size must also be set
> appropriately for this module to be active"
> These parameters (aio read size and aio write size) are not set by default
> in the smb.conf. The manpage implies that this would render the
> vfs_aio_pthread module inactive. I have a few questions in this direction.
> 
> 1) Is my understanding of the manpage correct?

Yes.

> 2) Is there a quick and easy way of determining async I/O is being
> performed via CIFS?

No :-).

> 3) Are the any good rules of thumb for determining proper aio read and
> write sizes?

If you want aio, just set sizes to 1 (make all I/O aio).

FYI. In latest Samba versions 4.1.x, pthread aio is automatically
built-in by default. You don't need to use aio_pthread any more.

> For reference, a typical share is set up as follows:
> 
> [Users]
>     path = /mnt/Tank/Users
>     printable = no
>     veto files = /.snap/.windows/.zfs/
>     writeable = yes
>     browseable = yes
>     recycle:repository = .recycle/%U
>     recycle:keeptree = yes
>     recycle:versions = yes
>     recycle:touch = yes
>     recycle:directory_mode = 0777
>     recycle:subdir_mode = 0700
>     vfs objects = zfsacl streams_xattr aio_pthread
>     hide dot files = yes
>     guest ok = no
>     nfs4:mode = special
>     nfs4:acedup = merge
>     nfs4:chown = yes
>     zfsacl:acesort = dontcare
> 
> Any pointers would be much appreciated.
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