Lots of folk use a single disk or raid-1 for the system and commit log and raid-0 for the data volumes http://wiki.apache.org/cassandra/CassandraHardware
Your money is probably better spent on more nodes with more disks and more memory. More nodes is always better. Happy to hear reasons otherwise. Cheers ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 15 Jun 2011, at 15:50, Marcos Ortiz wrote: > > > El 6/14/2011 1:43 PM, Eric Czech escribió: >> >> Thanks Aaron. I'll make sure to copy the system tables. >> >> Another thing -- do you have any suggestions on raid configurations for main >> data drives? We're looking at RAID5 and 10 and I can't seem to find a >> convincing argument one way or the other. > Well, I learned from administrating other databases (like PostgreSQL and > Oracle) that RAID 10 is the best solution for data. With RAID 5, the discs > suffer a lot for the excesive I/O and It can arrive to > data lost. You can search about the "RAID 5 Write Hole" to view this. > >> >> Thanks again for your help. >> >> On Mon, Jun 6, 2011 at 5:45 AM, aaron morton <aa...@thelastpickle.com> wrote: >> Sounds like you are OK to turn off the existing cluster first. >> >> Assuming so, deliver any hints using JMX then do a nodetool flush to write >> out all the memtables and checkpoint the commit logs. You can then copy the >> data directories. >> >> The System data directory contains the nodes token and the schema, you will >> want to copy this directory. You may also want to copy the cassandra.yaml or >> create new ones with the correct initial tokens. >> >> The nodes will sort themselves out when they start up and get new IP's, the >> important thing to them is the token. >> >> Cheers >> >> ----------------- >> Aaron Morton >> Freelance Cassandra Developer >> @aaronmorton >> http://www.thelastpickle.com >> >> On 6 Jun 2011, at 23:25, Eric Czech wrote: >> >> > Hi, I have a quick question about migrating a cluster. >> > >> > We have a cassandra cluster with 10 nodes that we'd like to move to a new >> > DC and what I was hoping to do is just copy the SSTables for each node to >> > a corresponding node in the new DC (the new cluster will also have 10 >> > nodes). Is there any reason that a straight file copy like this wouldn't >> > work? Do any system tables need to be moved as well or is there anything >> > else that needs to be done? >> > >> > Thanks! >> >> > > -- > Marcos Luís Ortíz Valmaseda > Software Engineer (UCI) > http://marcosluis2186.posterous.com > http://twitter.com/marcosluis2186 >
