fix re-open failure issue when using gluster ioengine

[fio.git] / fio.1

diff --git a/fio.1 b/fio.1
index b5ff3ccbc4633dd0cf92ad42a59efe660d64e848..c61948bb52814a2a6bac248c5db0063406225a48 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -613,8 +613,16 @@ Using Glusterfs libgfapi async interface to direct access to Glusterfs volumes w
 having to go through FUSE. This ioengine defines engine specific
 options.
 .TP
-.B hdfs
-Read and write through Hadoop (HDFS)
+.B libhdfs
+Read and write through Hadoop (HDFS).  The \fBfilename\fR option is used to
+specify host,port of the hdfs name-node to connect. This engine interprets
+offsets a little differently. In HDFS, files once created cannot be modified.
+So random writes are not possible. To imitate this, libhdfs engine expects
+bunch of small files to be created over HDFS, and engine will randomly pick a
+file out of those files based on the offset generated by fio backend. (see the
+example job file to create such files, use rw=write option). Please note, you
+might want to set necessary environment variables to work with hdfs/libhdfs
+properly.
 .RE
 .P
 .RE