[CentOS] Samba "use sendfile" configuration option set do disabled as default - why?

This is not problem of disks, this is problem of Samba (operating
systems in network are Windows XP and Windows 7 only, so this should
not be problem caused by Windows).

I am asking because of risks and disadvantages. This is same as
oplocks - it may be performance tweak, but it is potentially dangerous
(data corruption).

Thank you

2009/8/24 JohnS <jses27 at gmail.com>:
>
> On Mon, 2009-08-24 at 15:41 +0200, happymaster23 wrote:
>> Thank you for replies,
>>
>> with option "use sendfile = yes" it works great (with good speed), but
>> I am asking why is this option in CentOS disabled as default, even in
>> standard samba build it should be (according to Samba release notes)
>> enabled as default.
>>
>> So my question is, why in CentOS´s Samba build is this option as
>> default disabled. Is it experimental? Is it potentially dangerous?
>> (Something like oplocks?)
> ---------------
> Why is it disabled? You need to ask the "Samba Devel List" that. Just an
> example an i586 class machine with 4 Nics will saturate a gig E
> connection easily. Its all all about disk throughput and how many disc
> spindles you have. Maybe this will explain it to you! :-) Winblows
> related mostly.
>
> Hint use "man smb.conf"
>
>  use sendfile (S)
>             If this parameter is yes, and the sendfile() system call is
> supported by the  underlying  operating
>             system, then some SMB read calls (mainly ReadAndX and
> ReadRaw) will use the more efficient sendfile
>             system call for files that are exclusively oplocked. This
> may make more efficient use of the system
>             CPU’s  and cause Samba to be faster. Samba automatically
> turns this off for clients that use proto-
>             col levels lower than NT LM 0.12 and when it detects a
> client is Windows 9x  (using  sendfile  from
>             Linux will cause these clients to fail).
>
>             Default: use sendfile = false
>
> JohnStanley
>
>
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