Re: MirrorMode VS load balancing

[Hideo NAKAMITSU <nomo@bluecoara.net>]

Hi, Brett,

On Tue, 30 Jun 2009 19:58:07 +1000
Brett Maxfield <brett.maxfield@gmail.com> wrote:

> Yes simple is a good thing, but you have to decide for yourself what risk and downtime is acceptable, how long to recover and how many writes is acceptable to lose.
> 
> E.g. Is a one daily backup acceptable for recovery (and you lose changes since then), or do you need every single write to the hour/minute ?
> 
> The more continously/frequently you write to both nodes, the more likely are sync errors, and also less recoverability of  your bdb logs in the event of catastrophic power failure or inproper shutdown.
> 
> I dont think anyone can decide this for you.. You need to evaluate your level of risk and what loss / downtime is acceptable to you / your employer / your customers etc.,

Thanks for your impression.

actually, I was thinking it's very difficult to answer YES or NO.
even if there are few writes, it may cause database corruption at the worst case.

it's not 100% safe, but in most cases, must be 99.99% safe.
but in case of failure, it's important to monitor every nodes, and 
if the difference is found, administrator must fix it by hands from
backup or such.

anyway, it was good opportunity to know not only me
but also your thoughts.

Regards,