From: Mikael Ronström Date: July 1 2004 12:59pm Subject: Various answers to questions on the list List-Archive: http://lists.mysql.com/cluster/68 Message-Id: <8A8FD8D6-CB5E-11D8-A693-000A959312A2@mysql.com> MIME-Version: 1.0 (Apple Message framework v618) Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Hi all, Adding some answers and comments to a number of questions discussed on=20= the cluster list. Q1) Regarding the question of having 1 mysql server on each web server=20= with storage nodes in a central location. Answer: This is one possible configuration set-up which makes sense. Currently=20= there is one limitation that there can be a maximum of 63 nodes in the cluster. So if you have 1 management server,=20= 4 DB nodes that provides the possibility to have 58 MySQL servers in the cluster. This limitation is simply a compile time constant so is fairly simple=20 to update. The drawback of upgrading it is that there are some loops that become longer and also the DB nodes will have=20= more work in checking for incoming messages due to the increased number of TCP/IP connections. Essentially=20= this is a question of how many servers to support before adding a new tier in the architecture. Q2) Regarding suitable Hardware The recommended HW is recommended since it is a clustered main memory=20 database. The minimum HW needed is much smaller. I am developing on a Mac with 1 GB of memory and I can=20 run 4 storage nodes on this machine. Of course the database size becomes very limited then. For production usage it is very important to ensure that the machine doesn't start swapping. For high availability purposes the=20 process needs to send heartbeats every second or so. If the machine runs out of memory and starts swapping there are=20= no bounds on the time for heartbeats. We had a customer running a backup program every night that used a large=20 amount of memory and this caused node failures sometimes. They were running with about 1 GB of memory for the=20= storage node process and 2 GB memory in the machine and still got problems due to other processes consuming=20= large amounts of memory. It is thus important to run production machines in a controlled=20 environment if desiring a high availability system. As a side note one can mention that node failures are merely a glitch in MySQL=20 Cluster. So what we have recommended in the past as minimum HW is 512 MByte of=20 memory. 2 GB with 800MB database size should work out fine both for testing and=20= production. For a high availability set-up without single point of failures one=20 should also consider having dual Ethernet networks. There are lots of device drivers available that handles this. Q3) Various questions on platforms We are currently working on supporting all Unix-variants for MySQL=20 Cluster and have started work on Windows. In the development team we are using RH Linux, Mac OS X 10.3, Solaris 7 so=20 they get exercised regularly during the development process. The other OS's are handled at builds of new 4.1=20 and 5.0 releases. So please report any problems and solutions to those so that we can integrate those fixes in the source=20 code. Currently MySQL Cluster is only available from bitKeeper. It is not=20 included in the source code release of MySQL 4.1.2. If you experience problems also check the MySQL manual for a=20 description of the files containing logs of error and warning messages of various kinds. Some general comments: 1) In the past I have experienced problems at times with hostnames. On=20= some installations one should only use the hostname and not the full path, on other installations the opposite have been=20 the case where only full path in the hostname was ok. The storage nodes and MySQL servers call gethostname to get the IP-address=20= given the hostname provided in the config file. 2) Please check the MySQL manual regularly for updates on names of=20 files, changes to configuration files and so forth. We are currently working hard to make it easier to get up to speed quickly=20 with MySQL Cluster and thus some things are changing regularly. A new chapter has been added to the MySQL manual on MySQL=20 Cluster which should contain more and more answers to common questions. Rgrds Mikael Mikael Ronstr=F6m, Senior Software Architect MySQL AB, www.mysql.com Clustering: http://www.infoworld.com/article/04/04/14/HNmysqlcluster_1.html http://www.eweek.com/article2/0,1759,1567546,00.asp