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

JohnS jses27 at gmail.com
Mon Aug 24 14:58:47 UTC 2009

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


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