How to disable hard disk write cache?

[Xin Li]

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On 9/21/14 4:52 PM, Matthias Andree wrote:
> Am 21.09.2014 um 10:42 schrieb Xin Li:
>> On 9/21/14 4:34 PM, Matthias Andree wrote:
>>> Am 16.09.2014 um 16:09 schrieb Xin Li:
>> 
>>>> Modern SATA/SAS/SCSI devices usually comes with the
>>>> capability of tagged commands, allowing the OS to know when a
>>>> write buffer is on stable storage.  With this, file systems
>>>> can easily implement the right semantics and recover from
>>>> e.g. a power outage, etc.
>> 
>>> Yes, they *can easily implement* that, but which file systems
>>> in FreeBSD *actually do* that?
>> 
>> Both UFS (with Soft Updates, which is what it's all about; I
>> haven't checked the Journalled Soft Updates case) and ZFS do that
>> for ages.
> 
> Thank you.  Is this in any of the 9.3 manpages so I could look that
> up rather than ask questions on the lists? :-)

I don't really know...  I personally see it as a vital feature for any
file systems (or otherwise they become the cat who ate our homework :)
so I doubt if it's actually being explicitly documented.

This is probably a good FAQ candidate though.

Cheers,

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