[Samba] 答复: Is it fine to store the tdb files in the shared directory to solve the ctdb data synchronization problem?

[Chenyehua]

Thanks very much, Volker.

I want to synchronize three tdb files(listed as below) which is relevant to the opened file:
1) brlock.tdb
2) locking.tdb
3) smbXsrv_open_global.tdb
These three tdb files are used to realize the durable file handle feature.

As what you have said, the performance will be affected if storing these three files in the shared storage.
So can I realize the synchronization with the solutions below:
1) set these three tdb files as persistent tdb files to realize synchronization (Is this way even worse than storing in the shared storage when concerning the performance affecting?)
2) Real-time backing up the modification of the normal tdb to other ctdb nodes(just a simple guess, not test yet)
Do you have any other solutions or suggestions about this data synchronization problem?

Looking forward to your reply, thanks.
Best regards

-----邮件原件-----
发件人: vlendec at samba.org [mailto:vlendec at samba.org] 代表 Volker Lendecke
发送时间: 2016年12月2日 18:55
收件人: chenyehua 11692 (RD)
抄送: samba at lists.samba.org
主题: Re: [Samba] Is it fine to store the tdb files in the shared directory to solve the ctdb data synchronization problem?

On Fri, Dec 02, 2016 at 10:45:53AM +0000, Chenyehua via samba wrote:
>    I face a problem about the data synchronization when using the
>    ctdb. When one ctdb node fails, other ctdb nodes may not recover
>    the data of the failed node. I think it may be due to the fact
>    that ctdb stores its tdb files in the local storage. So, is it
>    fine to store the tdb files in the shared directory of the
>    backend storage? When one node fails, other nodes may recover the
>    data from the shared directory. Could this solve the ctdb data
>    synchronization problem? Are there any problems with this
>    solution?

The architecture of ctdb is such that it is supposed to lose the data that is stored on the local node in the tdb. For example information on open files is worthless if the node crashes, the files are closed by definition.

ctdb was explicitly designed to not store the tdb data on shared storage. Shared storage is not made for this workload: Heavy locking, tons of small writes all around in the file, high consistency requirements. This is nothing you want remote.

What data do you need to synchronize?

With best regards,

Volker Lendecke
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