On 2/23/10 4:34 PM, [email protected] wrote:
> On Tue, 23 Feb 2010, Rory Toma wrote:
>
>> I would like several front end servers writing to a single
>> file-system, but I would expect that, out-of-the-box I would get out
>> of order files and would have locking issues.
>
> Yes, if you use a standard filesystem you can only have one system
> writing to it at a time.
>
> If you want multiple systems to be able to write to a single
> filesystem you need to select a cluster filesystem or a network
> filesystem
>
> such a filesystem will allow multiple machines to write to different
> files on the shared filesystem at once, but they cannot write to the
> same file from different machines.
>
> all of the options have very different performance, reliability, and
> cost trade-offs. You will need to spend a lot of time thinking though
> your particular requirements and the capabilities of the different
> systems to pick one.
>
> I'm not sure exactly what you mean by 'out of order files', but if you
> are thinking that everything would end up in the same file and be in a
> different order than they were 'really' generated, then you are
> correct. The problem is that packets going over the network may not
> arrive in the same order that they were sent. Thus it is impossible
> for any system to guarantee the log entries reamin in the same order.
> the best that anything can do it to record very accurate timestamps
> and re-sort the logs after they have arrived.
>
> Very few people go down this road for logs. Almost everyone relays the
> logs to a single server and lets that server write to a filesystem
> (and if they need to eliminate this as a single point of failure, they
> make another system able to take over this filesystem if the first one
> goes down)
>
Yeah, I didn't think it was practical, but if someone had done something
unorthodox, and it worked, I thought it might be nice to hear about it.
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