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On 05/10/2013 12:46 PM, Merlin Moncure
wrote:
Well we have dual redundant power supplies on separate UPS so could something go wrong yes, but a tornado couldOn Fri, May 10, 2013 at 11:34 AM, Evan D. Hoffman <evandhoffman@xxxxxxxxx> wrote:I'd expect to use a RAID controller with either BBU or NVRAM cache to handle that, and that the server itself would be on UPS for a production DB. That said, a standby replica DB on conventional disk is definitely a good idea in any case.Sadly, NVRAM cache doesn't help (unless the raid controller is managing drive writes down to the flash level and no such products exist that I am aware of). The problem is that provide guarantees the raid controller still needs to be able to tell the device to flush down to physical storage. While flash drives can be configured to do that (basically write-through mode), it's pretty silly to do so as it will ruin performance and quickly destroy the drive. Trusting UPS is up to you, but if your ups does, someone knocks the power cable, etc you have data loss. With on-drive capacitor you only get data loss via physical damage or corruption on the drive. merlin come along and destroy the building also. --
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