# not able to desync and flush tables with read lock

**URL:** <https://forums.percona.com/t/not-able-to-desync-and-flush-tables-with-read-lock/5469>\
**Category:** Percona XtraDB Cluster 5.x\
**Created:** [March 9, 2017, 4:39pm UTC](https://forums.percona.com/t/not-able-to-desync-and-flush-tables-with-read-lock/5469 "2017-03-09T16:39:14Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![akang](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@akang](https://forums.percona.com/u/akang)\
**Post date:** [March 9, 2017, 4:39pm UTC](https://forums.percona.com/t/not-able-to-desync-and-flush-tables-with-read-lock/5469/1 "2017-03-09T16:39:14Z")

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Hi,

I have a cluster of 3 nodes and when i try to desync and flush tables with read lock in order to get a backup of the node for a slave, I get a few errors.

When I run the following commands in the command line on one of the nodes:

global wsrep\_desync=ON; flush tables with read lock;

I get the following error from the command line:

ERROR 1213 (40001): wsrep desync failed for FTWRL

In my error log, I see these error msgs:

2017-03-09 16:33:57 18704 [Note] WSREP: Member 0.0 (loaddb-56-node1) desyncs itself from group  
2017-03-09 16:33:57 18704 [Note] WSREP: Shifting SYNCED → DONOR/DESYNCED (TO: 11504643)  
2017-03-09 16:34:08 18704 [Warning] WSREP: Member 0.0 (loaddb-56-node1) requested state transfer from ‘self-desync’, but it is impossible to select State Transfer donor: Resource temporarily unavailable  
2017-03-09 16:34:08 18704 [ERROR] WSREP: Node desync failed.: 11 (Resource temporarily unavailable) at galera/src/replicator\_smm.cpp:desync():1680  
2017-03-09 16:34:08 18704 [Warning] WSREP: FTWRL desync failed 3 for schema: (null), query: flush tables with read lock

Also, when I run the following commands after running the commands listed above:

unlock tables; set global wsrep\_desync=OFF;

the error log show that it is shifting from donor/desynced to synced but when I type “show status like ‘wsrep%’”, it shows that the node is still donor/desynced.

2017-03-09 16:36:30 18704 [Note] WSREP: Member 0.0 (loaddb-56-node1) resyncs itself to group  
2017-03-09 16:36:30 18704 [Note] WSREP: Shifting DONOR/DESYNCED → JOINED (TO: 11504643)  
2017-03-09 16:36:30 18704 [Note] WSREP: Member 0.0 (loaddb-56-node1) synced with group.

The nodes in the cluster use Ubuntu 14.04.4 LTS and Percona xtradb cluster version 5.6.32-25.17-1.trusty.

Lastly, in order to sync the node back into the cluster, I need to force kill the mysql process and then let it SST.

Any help/feedback is appreciated.

Best,

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<div class="post-metadata">

**Author:** ![przemek](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/przemek/32/3_2.png) [@przemek](https://forums.percona.com/u/przemek)\
**Post date:** [March 22, 2017, 8:15am UTC](https://forums.percona.com/t/not-able-to-desync-and-flush-tables-with-read-lock/5469/2 "2017-03-22T08:15:21Z")

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Hi,

First of all, in the latest PXC versions, a FTWRL does implicitly turn on desync mode, so no need to set the desync mode explicitly any more.  
Secondly, I can see that apparently this buggy behavior is back:

> **[Bug #1370532 “Setting wsrep\_desync=1 after FTWRL blocks a node” : Bugs :...](https://bugs.launchpad.net/percona-xtradb-cluster/+bug/1370532)**
>
> Tested the problem below on PXC 5.5.37, 5.6.20 and Maria Cluster 10.0.13.
> 
> percona33 mysql\> flush tables with read lock;
> Query OK, 0 rows affected (0.00 sec)
> \-- err log on the same node:
> 2014-09-17 12:46:25 16422 \[Note\] WSREP: Provider paused at...

maybe you’ve hit some side effect of this problem. Any way, doing this sequence:  
flush tables with read lock; set global wsrep\_desync=1;  
puts a node in permanent Donor/Desynced mode, where only killing mysql can unblock it.