After patching my box a few months back, I noticed the following messages on the console after I rebooted:
Apr 15 15:23:15 winnie md_mirror: [ID 437521 kern.info] NOTICE: md: d1: B_FAILFAST I/O disabled
Apr 15 15:23:15 winnie md_mirror: [ID 437521 kern.info] NOTICE: md: d2: B_FAILFAST I/O disabled
Apr 15 15:23:15 winnie md_mirror: [ID 437521 kern.info] NOTICE: md: d1: B_FAILFAST I/O disabled
Apr 15 15:23:15 winnie md_mirror: [ID 437521 kern.info] NOTICE: md: d2: B_FAILFAST I/O disabled
Due to the nature of the message, I grew somewhat frantic, and began feverishly scouring the Internet for answers. It didn’t take long to stumble across the following Sunsolve article. According to sunsolve, these are not errors, and the metadevices are not faulted:
“These are not errors. These are informational (NOTICE) messages telling you that the driver underlying your metadevices does not support the B_FAILFAST option and, as a result, that capability will not be active for speedier recovery. There is no way to disable these messages.”