[CentOS] LSI/3ware 9750-4i and multipath I/O
Ross Walker
rswwalker at gmail.com
Fri Jan 13 23:56:40 UTC 2012
On Jan 13, 2012, at 6:51 PM, John R Pierce <pierce at hogranch.com> 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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