Re: write cache (win/Storage)
- From: Arno Wagner <me@xxxxxxxxxxx>
- Date: 18 Jul 2008 08:35:58 GMT
Previously Ingo <Ingo@xxxxxxxxx> wrote:
According to technet the option to "enable write cache" in the policies
window (w2k3) always has an impact on the setting of the underlying
storage, no matter if it's a single dumb sata disk or a high-end
storage-subsystem with integrated RAID-controller.
I do understand that this setting always implies windows OS caching.
Or is it a driver's setting?
All tests I did confirmed that behaviour regarding IBM DS4700 storage.
When you tick the option the IBM storage manager shows an altered
setting as well. So obviously SCSI commands trigger the setting on the DS.
If hard disk caching is disabled, performance drops to 15% (SATA, duh).
Now I want to DISABLE windows OS caching completely, but leave caching
on for the underlying storage.
Would that sound reasonable (and possible)?
Not really. UNless you do not trust your OS. For Windows, this
may still be a reasonable idea, as the technology is not up
to the standards of other OSes.
As to whether it is possible, you can only disable OS buffering.
I thinkt his wirks by marking the device as "removable".
You will still get application buffering. What you do not want to
disable is caching. Caching only influences read access, by
delivering already read stuff from memory (MS here again
confuses the terminologuy: There is no write caching. It is
either read caching or write buffering).
Arno
.
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