samba - Sep 2016 - Confused about ctdb options: dbdir and dbdir-persistent

Hi all
http://linux.die.net/man/1/ctdbd. In this page, it says “This directory is local
for each node and should not be stored on the shared cluster filesystem”. But
why?  Thanks for reply.

--dbdir=<directory>
This is the directory on local storage where ctdbd keeps the local copy of the
TDB databases. This directory is local for each node and should not be stored on
the shared cluster filesystem.

--dbdir-persistent=<directory>
This is the directory on local storage where ctdbd keeps the local copy of the
persistent TDB databases. This directory is local for each node and should not
be stored on the shared cluster filesystem.

Weidong
-------------------------------------------------------------------------------------------------------------------------------------
本邮件及其附件含有杭州华三通信技术有限公司的保密信息，仅限于发送给上面地址中列出
的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、
或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本
邮件！
This e-mail and its attachments contain confidential information from H3C, which
is
intended only for the person or entity whose address is listed above. Any use of
the
information contained herein in any way (including, but not limited to, total or
partial
disclosure, reproduction, or dissemination) by persons other than the intended
recipient(s) is prohibited. If you receive this e-mail in error, please notify
the sender
by phone or email immediately and delete it!

On Wed, 14 Sep 2016 10:21:39 +0000, Weidong via samba
<samba at lists.samba.org> wrote:
> http://linux.die.net/man/1/ctdbd. In this page, it says “This
> directory is local for each node and should not be stored on the
> shared cluster filesystem”. But why?  Thanks for reply.
I believe that the answer is performance.  This is mentioned here:

  https://wiki.samba.org/index.php/Clustered_Samba#Clustered_Samba_Prototypes

Instead, CTDB manages record distribution and replication between local
databases stored on each node.  For most SMB workloads it does this
very efficiently.

peace & happiness,
martin