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VA 7110 - Write cache

Paresh Raja
Occasional Visitor

VA 7110 - Write cache

Hello,
I was told that if you have single controller in VA7110,write cache is disabled.Do you require 2 controllers to enable write cache in VA7110.If you have only 1 controller,what happens to your write cache by default ? Is it enabled or diabled ?

Appriciate a quick reply.
Thanks in advance.
5 REPLIES
Michael Schulte zur Sur
Honored Contributor

Re: VA 7110 - Write cache

Hi,

I have been looking into the manual for the va7110 but couldn't find any reference to that. Also it wouldn't make much sense. How do you configure the controller and which one is it. I have to admit, I not much into this, but I want to learn and if possible help you.

Michael
Michael Schulte zur Sur
Honored Contributor

Re: VA 7110 - Write cache

Hi,

I have found a doc where it says something about secure mode:
http://www.hp.com/products1/storage/products/disk_arrays/midrange/da_perf_guide.pdf

Maybe this is the case with you.

Michael
Paresh Raja
Occasional Visitor

Re: VA 7110 - Write cache

Hi Michael

Thanks for your help.
I went through the document you referred and I also read command SDM manual.But nowhere it says that if you have one controller then cache is disabled by default or enabled.SDM manual says that you can use "armmgr -J" command to set resiliancy parameter.

I have following question.

1. For single controller,can you enable normal and high performance mode or you can select only Single controller mode ?

Thanks and best regards.

Paresh
Michael Schulte zur Sur
Honored Contributor

Re: VA 7110 - Write cache

Hi,

have you tried to connect a pc to the rsr-232 port with a null modem cable according to the desciption in the docs?

Michael
Ted Buis
Honored Contributor

Re: VA 7110 - Write cache

If you only have a single controller, and the write cache is not disabled, you are running a greater risk of data loss. If the array has a failure prior to the writing of the data and the write cache is not disabled, then data would be lost, but the server would think that all the data was properly written. Therefore, with a single controller write cache should be disabled by default and one should consider carefully before enabling it. If you only want a single controller, a SmartArray controller PCI card is much less expense than a VA7xxx array if you are willing to tolerate a single point of failure with a single controller.
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