Hi! I'm considering setting up a small (4-6 nodes) Cassandra cluster on machines that each have 3x2TB disks. There's no hardware RAID in the machine, and if there were, it could only stripe single disks together, not parts of disks.
I'm planning RF=2 (or higher). I'm pondering what the best disk configuration is. Two alternatives: 1) Make small partition on first disk for Linux installation and commit log. Use Linux' software RAID0 to stripe the remaining space on disk1 + the two remaining disks into one large XFS partition. 2) Make small partition on first disk for Linux installation and commit log. Mount rest of disk 1 as /var/cassandra1, then disk2 as /var/cassandra2 and disk3 as /var/cassandra3. Is it unwise to put the commit log on the same physical disk as some of the data? I guess it could impact write performance, but maybe it's bad from a data consistency point of view? How does Cassandra handle replacement of a bad disk in the two alternatives? With option 1) I guess there's risk of files being corrupt. With option 2) they will simply be missing after replacing the disk with a new one. With option 2) I guess I'm limiting the size of the total amount of data in the largest CF at compaction to, hmm.. the free space on the disk with most free space, correct? Comments welcome! Thanks, \EF -- Erik Forsberg <forsb...@opera.com> Developer, Opera Software - http://www.opera.com/
