Re: Raid 10 chunksize

On Wed, Apr 1, 2009 at 10:48 AM, Stef Telford <stef@ummon.com> wrote:
> Scott Marlowe wrote:
>> On Wed, Apr 1, 2009 at 10:15 AM, Stef Telford <stef@ummon.com> wrote:
>>
>>>     I do agree that the benefit is probably from write-caching, but I
>>> think that this is a 'win' as long as you have a UPS or BBU adaptor,
>>> and really, in a prod environment, not having a UPS is .. well. Crazy ?
>>>
>>
>> You do know that UPSes can fail, right?  En masse sometimes even.
>>
> Hello Scott,
>    Well, the only time the UPS has failed in my memory, was during the
> great Eastern Seaboard power outage of 2003. Lots of fond memories
> running around Toronto with a gas can looking for oil for generator
> power. This said though, anything could happen, the co-lo could be taken
> out by a meteor and then sync on or off makes no difference.

Meteor strike is far less likely than a power surge taking out a UPS.
I saw a whole data center go black when a power conditioner blew out,
taking out the other three power conditioners, both industrial UPSes
and the switch for the diesel generator.  And I have friends who have
seen the same type of thing before as well.  The data is the most
expensive part of any server.