[Gluster-users] How-to start gluster when only one node is up ?

Remi Serrano rserrano at pros.com
Fri Oct 30 12:01:38 UTC 2015 

Thank you Mauro.

Rémi

-----Message d'origine-----
De : Mauro Mozzarelli [mailto:mauro at ezplanet.net] 
Envoyé : vendredi 30 octobre 2015 12:58
À : Atin Mukherjee <atin.mukherjee83 at gmail.com>
Cc : Remi Serrano <rserrano at pros.com>; gluster-users at gluster.org
Objet : Re: [Gluster-users] How-to start gluster when only one node is up ?

Hi,

Atin keeps giving the same answer: "it is by design"

I keep saying "the design is wrong and it should be changed to cater for standby servers"

In the meantime this is the workaround I am using:
When the single node starts I stop and start the volume, and then it becomes mountable. On CentOS 6 and CentOS 7 it works with release up to 3.7.4. Release 3.7.5 is broken so I reverted back to 3.7.4.

In my experience glusterfs releases are a bit of a hit and miss. Often something stops working with newer releases, then after a few more releases it works again or there is a workaround ... Not quite the stability one would want for commercial use, and thus at the moment I can risk using it only for my home servers, hence the cluster with a node always ON and the second as STANDBY.

MOUNT=/home
LABEL="GlusterFS:"
if grep -qs $MOUNT /proc/mounts; then
    echo "$LABEL $MOUNT is mounted";
    gluster volume start gv_home 2>/dev/null else
    echo "$LABEL $MOUNT is NOT mounted";
    echo "$LABEL Restarting gluster volume ..."
    yes|gluster volume stop gv_home > /dev/null
    gluster volume start gv_home
    mount -t glusterfs sirius-ib:/gv_home $MOUNT;
    if grep -qs $MOUNT /proc/mounts; then
        echo "$LABEL $MOUNT is mounted";
        gluster volume start gv_home 2>/dev/null
    else
        echo "$LABEL failure to mount $MOUNT";
    fi
fi

I hope this helps.
Mauro

On Fri, October 30, 2015 11:48, Atin Mukherjee wrote:
> -Atin
> Sent from one plus one
> On Oct 30, 2015 4:35 PM, "Remi Serrano" <rserrano at pros.com> wrote:
>>
>> Hello,
>>
>>
>>
>> I setup a gluster file cluster with 2 nodes. It works fine.
>>
>> But, when I shut down the 2 nodes, and startup only one node, I 
>> cannot
> mount the share :
>>
>>
>>
>> [root at xxx ~]#  mount -t glusterfs 10.32.0.11:/gv0 /glusterLocalShare
>>
>> Mount failed. Please check the log file for more details.
>>
>>
>>
>> Log says :
>>
>> [2015-10-30 10:33:26.147003] I [MSGID: 100030] 
>> [glusterfsd.c:2318:main]
> 0-/usr/sbin/glusterfs: Started running /usr/sbin/glusterfs version 
> 3.7.5
> (args: /usr/sbin/glusterfs -127.0.0.1 --volfile-id=/gv0
> /glusterLocalShare)
>>
>> [2015-10-30 10:33:26.171964] I [MSGID: 101190]
> [event-epoll.c:632:event_dispatch_epoll_worker] 0-epoll: Started 
> thread with index 1
>>
>> [2015-10-30 10:33:26.185685] I [MSGID: 101190]
> [event-epoll.c:632:event_dispatch_epoll_worker] 0-epoll: Started 
> thread with index 2
>>
>> [2015-10-30 10:33:26.186972] I [MSGID: 114020] [client.c:2118:notify]
> 0-gv0-client-0: parent translators are ready, attempting connect on 
> transport
>>
>> [2015-10-30 10:33:26.191823] I [MSGID: 114020] [client.c:2118:notify]
> 0-gv0-client-1: parent translators are ready, attempting connect on 
> transport
>>
>> [2015-10-30 10:33:26.192209] E [MSGID: 114058]
> [client-handshake.c:1524:client_query_portmap_cbk] 0-gv0-client-0: 
> failed to get the port number for remote subvolume. Please ume status' 
> on server to see if brick process is running.
>>
>> [2015-10-30 10:33:26.192339] I [MSGID: 114018]
> [client.c:2042:client_rpc_notify] 0-gv0-client-0: disconnected from 
> gv0-client-0. Client process will keep trying to connect t brick's 
> port is available
>>
>>
>>
>> And when I check the volumes I get:
>>
>> [root at xxx ~]# gluster volume status
>>
>> Status of volume: gv0
>>
>> Gluster process                             TCP Port  RDMA Port  Online
> Pid
>>
>>
> ----------------------------------------------------------------------
> --------
>>
>> Brick 10.32.0.11:/glusterBrick1/gv0         N/A       N/A        N
> N/A
>>
>> NFS Server on localhost                     N/A       N/A        N
> N/A
>>
>> NFS Server on localhost                     N/A       N/A        N
> N/A
>>
>>
>>
>> Task Status of Volume gv0
>>
>>
> ----------------------------------------------------------------------
> --------
>>
>> There are no active volume tasks
>>
>>
>>
>> If I start th second node, all is OK.
>>
>>
>>
>> Is this normal ?
> This behaviour is by design. In a multi node cluster when GlusterD 
> comes up it doesn't start the bricks until it receives the 
> configuration from its one of the friends to ensure that stale 
> information is not been referred.
> In your case since the other node is down bricks are not started and 
> hence mount fails.
> As a workaround, we recommend to add a dummy node to the cluster to 
> avoid this issue.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Rémi
>>
>>
>>
>>
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--
Mauro Mozzarelli
Phone: +44 7941 727378
eMail: mauro at ezplanet.net

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