[EMAIL PROTECTED] schrieb:
What about IDE drives (PATA, SATA). Currently only the sd driver implements
enabling/disabling the write cache?
They typically have write caches enabled by default; and some
don't take ckindly to disabling the write cache or do not allow
it at all.
But you could at least try. enabling/disabling the write cache and flushing
the cache are both described in the ATA/ATAPI standard (at least ATA/ATAPI-5
onwards).
Currently the IDE driver does (by default) exactly the opposite: it always
turns on the write cache regardless of how you set up the drive:
http://cvs.opensolaris.org/source/xref/on/usr/src/uts/intel/io/dktp/controller/ata/ata_disk.c#ata_write_cache
But disabling the write cache on ATA drives makes only sense if you support
command queueing (TCQ/NCQ). Otherwise write performance of these drives is
plain bad.
Daniel
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