docs: add a note about RAID-0 Adds a note that a single RAID-0 device with multiple disks is not preferable to specifying multiple fs directories across multiple disks.
Change-Id: Ibb17fae9459be04211bd0a7db6eca8e94e443f71 Reviewed-on: http://gerrit.cloudera.org:8080/11580 Reviewed-by: Adar Dembo <[email protected]> Tested-by: Kudu Jenkins Project: http://git-wip-us.apache.org/repos/asf/kudu/repo Commit: http://git-wip-us.apache.org/repos/asf/kudu/commit/fb79f8fc Tree: http://git-wip-us.apache.org/repos/asf/kudu/tree/fb79f8fc Diff: http://git-wip-us.apache.org/repos/asf/kudu/diff/fb79f8fc Branch: refs/heads/master Commit: fb79f8fccf6c6000f2569afb7fa2e41b02fdfe00 Parents: 75472c8 Author: Andrew Wong <[email protected]> Authored: Thu Oct 4 12:40:44 2018 -0700 Committer: Andrew Wong <[email protected]> Committed: Thu Oct 4 22:58:49 2018 +0000 ---------------------------------------------------------------------- docs/configuration.adoc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/kudu/blob/fb79f8fc/docs/configuration.adoc ---------------------------------------------------------------------- diff --git a/docs/configuration.adoc b/docs/configuration.adoc index 6a0a7f0..ebc1636 100644 --- a/docs/configuration.adoc +++ b/docs/configuration.adoc @@ -74,7 +74,11 @@ 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`. +blocks will be placed in the directory specified by `--fs_wal_dir`. Note that +while a single data directory backed by a RAID-0 array will outperform a single +data directory backed by a single storage device, it is better to let Kudu +manage its own striping over multiple devices rather than delegating the +striping to a RAID-0 array. 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
