copies of these files are getting slower and slower

[Andreas Schneider]

On Wednesday, 26 April 2017 17:00:54 CEST vl--- via samba-technical wrote:
> On Wed, Apr 26, 2017 at 07:37:06AM -0700, Richard Sharpe via samba-technical 
wrote:
> > On Wed, Apr 26, 2017 at 1:18 AM, Liuxuan via samba-technical
> > 
> > <samba-technical at lists.samba.org> wrote:
> > > Hi,everyone:
> > > 
> > > Recently,I meet a performance problem ,when I use Samba 4.2.11 to copy
> > > files from windows to linux. copies of these files are getting slower
> > > and slower quickly. But when I set the “case sensitive = yes” in
> > > smb.conf, it works very well. Can anyone help me? How should I deal
> > > with this problem when I use case “sensitive = yes”?
> > > 
> > > The protocol is SMB2_10 and file size is 105KB.
> > 
> > This is a well known issue. Since Samba is trying to provide the same
> > semantics as Windows, eg Case Preserving, Case Insensitive, when you
> > try to create a file, it:
> > 
> > 1. stat's the name as presented to check for existence, but if that fails,
> > 2. It has to search the directory for case-equivalent names.
> > 
> > Only if 2 fails can it go ahead and create a new problem.
> > 
> > This is an O(N^2) problem.
> > 
> > By telling Samba that the file system is case sensitive you skip step
> > 2. However, there be dragons unless you actually have a file system,
> > like XFS or ZFS that can do case-insensitive lookups ...
> 
> In addition: In case the original poster is working for an OEM with
> control over the file system, the OEM should take a look at the
> getrealfilename VFS operation that can hook into case-insensitive
> indexing operations inside a case-sensitive file system. This was
> created for GPFS, which can do an efficient case-insensitive search
> with a special ioctl.

We also have a section in the wiki:

https://wiki.samba.org/index.php/
Performance_Tuning#Directories_with_a_Large_Number_of_Files

-- 
Andreas Schneider                   GPG-ID: CC014E3D
Samba Team                             asn at samba.org
www.samba.org