Ric Wheeler wrote:
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.
Thank you very much for the information!
How can I check that I have a validated, working barrier with my
particular kernel version etc.?
(Do I just assume that since it's not SCSI, it doesn't work?)
I find it, hmm... stupefying? horrendous? completely brain dead? I
don't know.. that noone warns users about this. I bet there's a
million people out there, happily using MD (probably installed and
initialized it with Fedora Core / anaconda) and thinking their data is
safe, while in fact it is anything but. Damn, this is not a good
situation..
(Any suggestions for a good place to fix this? Better really really
really late than never...)
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