# SST-Problem, memory question **URL:** \ **Category:** Percona XtraDB Cluster 5.x\ **Created:** [September 13, 2012, 6:06am UTC](https://forums.percona.com/t/sst-problem-memory-question/2472 "2012-09-13T06:06:03Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![rwunderer](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/rwunderer/32/8934_2.png) [@rwunderer](https://forums.percona.com/u/rwunderer)\ **Post date:** [September 13, 2012, 6:06am UTC](https://forums.percona.com/t/sst-problem-memory-question/2472/1 "2012-09-13T06:06:03Z")
Hi. I am currently doing a trial setup of Percona Cluster and I am facing three problems, with the third one one probably caused by the other two. The setup is: OS: CentOs 6.2 Cluster: Percona-XtraDB-Cluster-5.5.27-23.6.356, installed from tarball The HW is 3 servers with Intel i7-920 Quad-Core w/ Hyperthreading (8 logical CPUs) and 24GB of RAM. MySQL configuration resides in /etc/mysql/my.cnf, the root user has a private configuration file in /root/.my.cnf The size of the database on disk is about 1.3TB The intended intial setup is: clusterdb1: slave of production server clusterdb2, clusterdb3: cluster members without special purpose The cluster gets started on all servers by root issuing /etc/init.d/mysql.server with the MySQL server configured to run a user “mysql”. The problems I am facing are: 1. SST does not work - it crashes when applying the logs because wsrep\_sst\_xtrabackup gets called with /root/.my.cnf as the configuration file. 2. innodb\_buffer\_pool\_size is currently set to 14GB (on dedicated servers with 24GB of RAM), still clusterdb1 keeps on crashing with out-of-memory error after running for about 15hours. 3. custerdb1 gets restarted immediately by mysqld\_safe and should definitely be able to do an IST, however that fails with [Warning] WSREP: Failed to prepare for incremental state transfer: Local state seqno is undefined: 1 (Operation not permitted) at galera/src/replicator\_str.cpp:prepare\_for\_IST():449. IST will be unavailable. After that clusterdb1 starts an SST (which will fail because of --defaults-file=/root/.my.cnf) So my questions are: 1. how to configure the my.cnf file used by PXC for SST? Why does it choose /root/.my.cnf? 2. what is the recommended memory setting for Percona Xtradb Cluster? How much memory has to be reserved for “cluster purposes”? (non-cluster MySQL works fine with 18GB of buffer\_pool on these machines) 3. Why doesn’t IST work? exactly what operation is not permitted? If the answer to 3. requires a more detailed log I will post that however I suspect that this is problably related to 1. (as SST fails with “operation not permitted” because the mysql user cannot read /root/.my.cnf). Regards, Robert. ---
**Author:** ![rwunderer](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/rwunderer/32/8934_2.png) [@rwunderer](https://forums.percona.com/u/rwunderer)\ **Post date:** [September 14, 2012, 1:47am UTC](https://forums.percona.com/t/sst-problem-memory-question/2472/2 "2012-09-14T01:47:33Z")
Ok, answering 3. myself: IST obviously does not work because the server in question crashed. When stopping one server and starting it again a clean and fast IST is done. The most pressing question for me is still the one about /root/.my.cnf being used as config file for SST. From other threads in this forum I gather that it works for some people. Is PXC supposed to be run as root? Robert. ---
**Author:** ![rwunderer](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/rwunderer/32/8934_2.png) [@rwunderer](https://forums.percona.com/u/rwunderer)\ **Post date:** [September 21, 2012, 12:02pm UTC](https://forums.percona.com/t/sst-problem-memory-question/2472/3 "2012-09-21T12:02:24Z")
I found the reason for the excessive memory use / memory leak: when using Percona XtraDB Cluster as a slave you have to enable bin\_log and set log\_slave\_updates=1. If binlog is not enabled the server will start to accumulate memory until it gets killed by the OOM killer. Either this is a bug or I have missed something very fundamental about the workings of Percona Cluster / Galera replication. Robert.