On Thu, Feb 12 at 21:45, Mattias Pantzare wrote:
A read of data in the disk cache will be read from the disk cache. You
can't tell the disk to ignore its cache and read directly from the
plater.
The only way to test this is to write and the remove the power from
the disk. Not easy in software.
Not true with modern SATA drives that support NCQ, as there is a FUA
bit that can be set by the driver on NCQ reads. If the device
implements the spec, any overlapped write cache data will be flushed,
invalidated, and a fresh read done from the non-volatile media for the
FUA read command.
--eric
--
Eric D. Mudama
edmud...@mail.bounceswoosh.org
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
