JBOD and system keyspaces

[Stuart Bishop <st...@stuartbishop.net>]

Hi.

I'm setting up a new cluster (DSE 4.7), and interested in failure
modes of JBOD setups. My main concern is the likelihood of needing to
rebuild an entire node whenever a single drive goes wobbly. After I
have replaced a failed or failing disk, how likely is it that it
contained critical information and the node unable to restart and
rejoin the cluster?

My current thinking is that the commitlog_directory and
savedcaches_directory should be on my OS RAID0 partition (just a pair
of small disks), with my data_file_directories pointing to my large
drives and not using RAID. Is this a good idea or a terrible one?

My alternative is to pay the capacity and write bandwidth penalties
and go RAID5, with the advantage that drives can be swapped out by
data center engineers without needing to shut the node down and
without lowered redundancy for several hours while the repair
completes.

-- 
Stuart Bishop <st...@stuartbishop.net>
http://www.stuartbishop.net/