[Dovecot] Best filesystem?
Stan Hoeppner
stan at hardwarefreak.com
Tue Feb 1 05:27:43 EET 2011
Frank Cusack put forth on 1/31/2011 3:13 PM:
> On 1/30/11 5:07 PM -0600 Stan Hoeppner wrote:
>> To be clear, for any subscribers who haven't followed all of the various
>> filesystem and data security threads, with any modern *nix system, you
>> WILL lose data when power fails.
>
> No, you won't, at least not necessarily.
>
> I know I'm replying with just about the same content multiple times
> but there are multiple messages where you are spreading this
> misinformation.
>
> It is possible to configure a file system to not suffer from data
> loss on power loss, and for mail stores that is generally the
> desired behavior.
Maybe not every time, but it should surely motivate OPs to look at their power
continuity solution(s).
Even using fsync et al, you can still lose data with power loss. It all depends
on what is in flight where, on which bus or cable, and whether the pulses made
it to the platters. fsync is a best effort. It can't guarantee all the
hardware was able to play its part correctly before the electrons stopped
flowing to the disk head actuator or spindle motor.
This is common sense. Anyone with the slightest knowledge of electricity and
background in electronics, and working with computers for any amount of time,
should realize this.
There is no 100% guarantee. This is one reason why the massive power backup
industry exists. The other is obviously avoiding downtime.
--
Stan
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