about active/active clustered nfs with ctdb
Martin Schwenke
martin at meltin.net
Wed Jan 27 09:46:13 UTC 2021
Hi,
On Fri, 22 Jan 2021 15:55:54 +0800 (CST), 风无名 via samba-technical
<samba-technical at lists.samba.org> wrote:
> I want to build a nfs cluster:
>
> 1) the nfs cluster consists of three nodes(linux servers)
>
> 2) each node has logined an iscsi lun, i.e.
>
> node_1 -> lun_1
>
> node_2 -> lun_2
>
> node_3 -> lun_3
>
> 3) make xfs file system on each lun
>
> 4) export each xfs file system via NFS
>
> node_1 -> lun_1-> /share-1
>
> node_2 -> lun_2-> /share-2
>
> node_3 -> lun_3-> /share-3
>
> 5) ctdb distributes public ips to the nodes
>
>
>
>
> if one node is failed, ctdb redistributes its public ip to another living node.
>
> and the shell scripts executed by ctdb on the node, will mount the file system, restart nfs service etc.
>
> if the failed node restarts, similar steps execute.
>
>
>
>
> I have written some shell scripts to implement the above process.
>
> I hope that during the lun/service moving process,
>
> the file io on the mount points of the corresponding lun is blocked for one or two minutes and succeeds after the moving process completed.
>
>
>
>
> My test result is:
>
> scenario 1: one node failed, another takes over its service
>
> the file io on the mount point will be blocked almost everytime
>
>
>
>
> scenario 2: failed node restarts
>
> the file io on the mount point sometimes is blocked, sometimes the io(open, write) will encounter some error.
>
>
>
>
> could I achieve my goal just through modifying/rewriting the shell script?
>
> or must I modify the kernel nfs or ctdb?
Are you using CTDB's 70.iscsi event script for this and adding the
extra scripts that it suggests?
Unfortunately, although I am one of the CTDB developers, I don't think
I have ever tested this script so I am not sure how reliable it is. :-(
I'm CC:ing Ronnie, who originally wrote this event script, to see if he
has any advice for you... if he can remember this at all... :-)
peace & happiness,
martin
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