Created attachment 123111 [details] dm-snapshot-barriers-not-supported
The snapshot target does not handle I/O barriers correctly so it should refuse to process them. Otherwise code that relies on them working could lead to data corruption.
The mapping functions always pass reads through to the underlying devices immediately, but writes may get delayed.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2006-0132.html