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Do "unconfigured" drives use Smart Array cache?

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Do "unconfigured" drives use Smart Array cache?

Dear colleagues,

could you please help me with Smart Array configuration? My mistake was to start configuring smart array after installing OS and a lot of software. Our server has 6 identical SAS 15K drives, attached to a P408i-p controller. I have created a RAID5 array from 5 of them, and the remaining one is displayed as "unconfigured". This "unconfigured" drive is a boot device, and it is also used for software installation. My question is - does it have to be assigned to a single-drive "RAID0" to be able to use the controller cache? Or is it using the cache anyway? And if it is required to assign it to an array, is there any way to do it without data loss?

Thanks in advance!

Best wishes,


Re: Do "unconfigured" drives use Smart Array cache?

Update: local support has clarified, that a drive must be assigned to an array to use the cache. The remaining question is how to do the transition without data loss.


Re: Do "unconfigured" drives use Smart Array cache?

Hi dvolkind ,

Unconfigured drives do not use cache. If the boot drive on which the OS is installed, the drive needs to be assigned. Please make sure you have a valid backup of all your data before performing the action.

Srinath Raju



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Re: Do "unconfigured" drives use Smart Array cache?

Your controller works in "mixed mode", so you can use logical RAID drives or the physical drives directly as you did.


The cache is bypassed for the physical disk access.

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Re: Do "unconfigured" drives use Smart Array cache?

Thank you, Torsten and Srinath! I decided not to take risk migrating the OS, but at least now I know how it works.