Re: hot spare / log shipping work on

Manfred Spraul wrote:

> Gaetano Mendola wrote:
> 
>>
>>         a1) If exist check that is a 16MB file ( the request can
>> ~                arrive during the copy ),
> 
> 
> I think this will fail under windows: "copy" first sets the file size 
> and then transfers the data. I wouldn't rule out that some Unices use 
> the same implementation.

I'm doing this work as "proof of concept", after made it working on
my platform we can even write them in C.



>> ~            a2) If the file not exist this mean that is not yet 
>> recycled and
>> ~                is a partial file present on the partial directory,
>> ~                check if the "alive" file is older then 2 minutes.
>> ~                   a21) If the file is older than 2 minutes I assume 
>> that
>> ~                        the master is dead:
> 
> 
> I'd concentrate on cold failover: the user (or the OS) must call a 
> script to cause a fail-over. The tricky thing are the various partial 
> connection losses between master and spare: perhaps the alive file is 
> not updated anymore due to a net split, but the master is still alive. 
> Unless you are really careful both master and spare could run.

I agree but as I said I'm doing it as "proof of concept", we can even change
later the way to discovery that master is dead.

I'm facing however to the following problems:

1) Discovery the actual WAL fileI'm supposing is the last modified file inside the        pg_xlog directory. If this is
notthe good method        may I know how I can know it ?
 

2) During the recovery phase postmaster ask me for file that will never be   there like:  00000001.history.Actualy if
thefile does not exist and contain the string history        instead to wait for him I exit with 1 exit code
 
Is this right for you ?



Regards
Gaetano Mendola