Molle Bestefich wrote:
NeilBrown wrote:
Change ENOTSUPP to EOPNOTSUPP
Because that is what you get if a BIO_RW_BARRIER isn't supported !
Dumb question, hope someone can answer it :).
Does this mean that any version of MD up till now won't know that SATA
disks does not support barriers, and therefore won't flush SATA disks
and therefore I need to disable the disks's write cache if I want to
be 100% sure that raid arrays are not corrupted?
Or am I way off :-).
You are absolutely right - if you do not have a validated, working
barrier for your low level devices (or a high end, battery backed array
or JBOD), you should disable the write cache on your RAIDed partitions
and on your normal file systems ;-)
There is working support for SCSI (or libata S-ATA) barrier operations
in mainline, but they conflict with queue enable targets which ends up
leaving queuing on and disabling the barriers.
ric
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