Directory configurations
Every Kudu node requires the specification of directory flags.
The --fs_wal_dir
configuration indicates
where Kudu will place its write-ahead logs.
The
--fs_metadata_dir
configuration indicates
where Kudu will place metadata for each tablet. It is recommended, although not necessary,
that these directories be placed on a high-performance drives with high bandwidth and low
latency, e.g. solid-state drives. If --fs_metadata_dir
is not specified, metadata will be placed in the directory
specified by --fs_wal_dir
.
Since a Kudu node cannot tolerate the loss of its WAL or metadata directories, you might want to mirror the drives containing these directories in order to make recovering from a drive failure easier. However, mirroring may increase the latency of Kudu writes.
The --fs_data_dirs
configuration indicates where Kudu will write its
data blocks. This is a comma-separated list of directories; if multiple values are
specified, data will be striped across the directories. If not specified, data blocks
will be placed in the directory specified by --fs_wal_dir
.
Additionally, --fs_wal_dir
and --fs_metadata_dir
may
be the same as one of the directories listed in --fs_data_dirs
,
but must not be sub-directories of any of them.