Disable read/write caching to disk?

[Eric Anderson]

Bjoern Koenig wrote:
> Bjoern Koenig wrote:
> 
>> Eric Anderson wrote:
>>
>>> Is it possible to disable all read and write caching to a disk?
>>
>>
>> You can disable write the cache by adding the line
>>
>>   hw.ata.wc="0"
> 
> 
> I assumed that you use ATA. If you use SCSI devices then read at least 
> the manpages da(4) and camcontrol(8).

Thanks.. I've just read (quickly) both man pages.  It seems as though 
you are suggesting disabling the physical disk caching, which should not 
make a difference in my case.  The disk would report whatever it needs 
to report to either host, and those should be in sync.

When I mount the filesystem on host B ro, it shows me the filesystem as 
of the time that I mounted it ro.  Any subsequent changes on host A 
(which has it mounted rw) are not seem on host B unless I unmount and 
mount again on host B.  This seems like a FreeBSD feature and not a 
general scsi feature.

Eric




-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
A lost ounce of gold may be found, a lost moment of time never.
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