Given a HDFS slave node setup of 3 disks per node, should I have 3
filesystems (one file system per disk) in my dfs.data.dir listing, or
should I have a single filesystem on a JBOD setup of 3 disks? Googling
this problem suggests using "JBOD" instead of RAID 0, but I'm talking
about two different kinds of JBOD: one managed by OS (mdadm) or firmware
with a single filesystem, and the other managed by the DataNode (with
multiple filesystems).
I already have a preference to providing multiple filesystems in the
dfs.data.dir listing since theoretically the DataNode should properly
handle where it would place its blocks (instead of abstracting this to
the OS or firmware). When a drive dies, I could also theoretically swap
in a new drive without worrying about crashing an entire JBOD array
(technically I only lose the blocks on the failing disk, not risking
filesystem level corruption). In some ways, I may already know the
answer to my question, I'm just looking for anyone's experience with
this datacenter-wide decision, or if they have a preference of one
method over another.
I'm trying to go along the lines as what is being done in this post:
http://old.nabble.com/forum/ViewPost.jtp?post=21423861&framed=y
