Add documentation for verify_backlog and verify_backlog_batch

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 19304aefc87d92bc6fd17a3fd28f6768c79f8550..d320ab3852dbc69942f69ddde8bbacd0aab127ce 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -899,6 +899,22 @@ verify_async=int   Fio will normally verify IO inline from the submitting
 verify_async_cpus=str  Tell fio to set the given CPU affinity on the
                async IO verification threads. See cpus_allowed for the
                format used.
+
+verify_backlog=int     Fio will normally verify the written contents of a
+               job that utilizes verify once that job has completed. In
+               other words, everything is written then everything is read
+               back and verified. You may want to verify continually
+               instead for a variety of reasons. Fio stores the meta data
+               associated with an IO block in memory, so for large
+               verify workloads, quite a bit of memory would be used up
+               holding this meta data. If this option is enabled, fio
+               will verify the previously written blocks before continuing
+               to write new ones.
+
+verify_backlog_batch=int       Control how many blocks fio will verify
+               if verify_backlog is set. If not set, will default to
+               the value of verify_backlog (meaning the entire queue
+               is read back and verified).
                
 stonewall      Wait for preceeding jobs in the job file to exit, before
                starting this one. Can be used to insert serialization