r271: update this document, too

diff --git a/README b/README
index da86a39..a53024a 100644 (file)
--- a/README
+++ b/README
@@ -68,6 +68,8 @@ This configuration file is expected to be found at
        readonly = false
        multifile = false
        copyonwrite = false
+       prerun = dd if=/dev/zero of=%s bs=1k count=500
+       postrun = rm -f %s
 [otherexport]
        exportname = /export/nbd/experiment
        port = 12346