Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Fri, Feb 10, 2006 at 11:37:30AM -0600, Nate Reed wrote: > > > > I must have lost track of the discussion. :) I didn't suggest running > > > MySql Cluster on a single node. Clearly, one has to choose between 1) > > > MySql clustering on multiple nodes and 2) using DRBD active/passive with > > > mysql running on a single node. Not both. > > > > and IIRC MySQL-Cluster has to keep the whole database in RAM ? > > I have to confess I am guilty of commenting about the original question while > being ignorant of some of the issues involved. Since I haven't used MySql > clustering before, I don't know anything about how it's implemented. I also > made an assumption about its use: replication of the database on multiple > nodes. There must be some kind of central coordination of access to the > mysql cluster, but I doubt it would be so inefficient as to require the > entire database to kept in RAM, any more than DRBD is required to keep an > entire filesystem in RAM.... > > Nate I have not used MySQL cluster either, and its a while since I looked into it. at http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-faq.html it says: How much RAM do I need? Is it possible to use disk memory at all? Currently, Cluster is in-memory only. This means that all table data (including indexes) is stored in RAM. Therefore, if your data takes up 1GB of space and you want to replicate it once in the cluster, you need 2GB of memory to do so. This in addition to the memory required by the operating system and any applications running on the cluster computers. You can use the following formula for obtaining a rough estimate of how much RAM is needed for each data node in the cluster: (SizeofDatabase × NumberOfReplicas × 1.1 ) / NumberOfDataNodes but, at http://dev.mysql.com/doc/refman/5.1/en/mysql-5-1-cluster-roadmap.html it says: Support for disk-based records: Records on disk will be supported. Indexed fields including the primary key hash index must still be stored in RAM but all other fields can be on disk. So that information may be out-of date now. dunno. Regards, Paddy -- Perl 6 will give you the big knob. -- Larry Wall