error out if ENOSPC during file layout

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index d8586723a281ae8418687fd2561a3f4b6ecaee26..386fd12aa7b14b80405a4df2851b3c0f7e967fd0 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1677,10 +1677,28 @@ Buffers and memory
        This will be ignored if :option:`pre_read` is also specified for the
        same job.
 
-.. option:: sync=bool
+.. option:: sync=str
+
+       Whether, and what type, of synchronous I/O to use for writes.  The allowed
+       values are:
+
+               **none**
+                       Do not use synchronous IO, the default.
+
+               **0**
+                       Same as **none**.
+
+               **sync**
+                       Use synchronous file IO. For the majority of I/O engines,
+                       this means using O_SYNC.
+
+               **1**
+                       Same as **sync**.
+
+               **dsync**
+                       Use synchronous data IO. For the majority of I/O engines,
+                       this means using O_DSYNC.
 
-       Use synchronous I/O for buffered writes. For the majority of I/O engines,
-       this means using O_SYNC. Default: false.
 
 .. option:: iomem=str, mem=str
 
@@ -2474,7 +2492,8 @@ I/O depth
        can increase latencies. The benefit is that fio can manage submission rates
        independently of the device completion rates. This avoids skewed latency
        reporting if I/O gets backed up on the device side (the coordinated omission
-       problem).
+       problem). Note that this option cannot reliably be used with async IO
+       engines.
 
 
 I/O rate