Re: LSI/3ware 9750-4i and multipath I/O

[Ross Walker <rswwalker@xxxxxxxxx>]

On Jan 13, 2012, at 6:51 PM, John R Pierce <pierce@xxxxxxxxxxxx> wrote:

> On 01/13/12 3:46 PM, Ross Walker wrote:
>> You will need to publish these disks as straight through individual disks with write-through cache and use software RAID if the controllers can't communicate with each other.
> 
> write-through cache is not even good enough.     if a given block is 
> written through one of them, it will land on the disk, but it won't 
> update the other controller cache, so the other controller could have 
> stale data in its cache and if another read takes that path, it will get 
> the old data, and things go downhill from there quickly.

And read-through too, bascially disable caching on the controllers.

-Ross

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