Write cache

Hi

Is there any way to use an MD RAID in write through mode? I
appreciate that there is a performance impact but this is important
from a security prospective....

The likelihood is that I would use RAID0 (I know this sounds like a
contradiction to the above, but the =91drives=92 are probably hardware
RAIDs). But may use standard RAID6.

I cannot see any way to disable write cache in MD, but I am hopefully
I am simply missing something obvious.

I appreciate any feedback....

Thanks, Mark
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Re: Write cache

On Thu, 2 Dec 2010 15:58:51 +0000 mark delfman com>
wrote:

> Hi
>=20
> Is there any way to use an MD RAID in write through mode? I
> appreciate that there is a performance impact but this is important
> from a security prospective....

MD RAID does work in write-through mode. I have occasionally thought a=
bout
adding a write-back mode which would make sense now that we have a sens=
ible
flushing infrastructure in Linux. But I haven't implemented it.

>=20
> The likelihood is that I would use RAID0 (I know this sounds like a
> contradiction to the above, but the =91drives=92 are probably hardwar=
e
> RAIDs). But may use standard RAID6.

RAID0 doesn't do any caching at all.

>=20
> I cannot see any way to disable write cache in MD, but I am hopefully
> I am simply missing something obvious.

Why do you think these is a write-behind cache in MD ??

NeilBrown



>=20
> I appreciate any feedback....
>=20
> Thanks, Mark
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> To unsubscribe from this list: send the line "unsubscribe linux-raid"=
in
> the body of a message to majordomo@vger.kernel.org
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Re: Write cache

Hi Neil,

Actually I made a silly presumption simply because MD is so fast
compared to most of the hardware raids I am testing =96 so I simple
presumed it was using write cache without really investigating it well
enough

Thank you for the feedback!



On Fri, Dec 3, 2010 at 1:27 AM, Neil Brown wrote:
> On Thu, 2 Dec 2010 15:58:51 +0000 mark delfman l.com>
> wrote:
>
>> Hi
>>
>> Is there any way to use an MD RAID in write through mode? =A0I
>> appreciate that there is a performance impact but this is important
>> from a security prospective....
>
> MD RAID does work in write-through mode. =A0I have occasionally thoug=
ht about
> adding a write-back mode which would make sense now that we have a se=
nsible
> flushing infrastructure in Linux. =A0But I haven't implemented it.
>
>>
>> The likelihood is that I would use RAID0 (I know this sounds like a
>> contradiction to the above, but the =91drives=92 are probably hardwa=
re
>> RAIDs). =A0But may use standard RAID6.
>
> RAID0 doesn't do any caching at all.
>
>>
>> I cannot see any way to disable write cache in MD, but I am hopefull=
y
>> I am simply missing something obvious.
>
> Why do you think these is a write-behind cache in MD ??
>
> NeilBrown
>
>
>
>>
>> I appreciate any feedback....
>>
>> Thanks, Mark
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-raid=
" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html
>
>
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To unsubscribe from this list: send the line "unsubscribe linux-raid" i=
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