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Dan
Asked: 2016-09-01 11:39:19 +0800 CST

GlusterFS - Weird Replication Issue

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I have a weird issue regarding glusterfs,

So ive setup a very simple replication volume accross two nodes using this command 

sudo gluster  volume create cloudStorage replica 2 transport tcp  machine1:/data  machine2:/data force

Ive then started the volume and mounted it on my two hosts (machine3, machine4) in /etc/fstab, this also works fine.

If I then create a folder on machine3 it will appear instantly on machine4 as available and is in the filesystem of machine2

If I then create a folder on machine4 it will appear on machine3's mount. But if i check machine1 the newly created folder doesn't appear. It eventually will appear on machine1's filesystem but is already available to machine3 to use and browse ? (machine1 can't browse to the newly created folder)

I plan to implement CTDB and im worried about a recovery file lock issue if gluster isn't replicating as it should be.

Im aware that this question may be abit vague so what I think im asking is

A) Why is replicating a single folder creation taking so long ?
B) Why does it take so long in one direction only ?
C) How can I improve the performance

A little background on the setup

The servers are

  • 2 ESXi
  • 2 Ubuntu 14.04 (glusterfs nodes)
  • 2 Ubuntu 16.04 (gluster client nodes)

They are linked between two ports in a draytek 2860N they are in the same building and the must be about 2 meters of cabling between the two ESXi hosts if that.

This image may help describe the problem

This May Help

ubuntu glusterfs

1 Answers

  1. Gluster doesn't replicate so much as allow each client to write to every relevant gluster node at the same time. This fan-out method of connectivity is what makes it so fast, but it is imperative that every client be able to connect to every gluster node.

    There is a method of server-to-server replication, but it's for back-end processes and for correcting replication problems caused by clients that weren't connected to all gluster nodes.

    Make sure that all clients have a stable connection to all storage nodes. If you have problems still, ort that doesn't help, please elaborate and I'll provide additional help.

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