>> I put the mysql datadir in /u/mysql and is ok.
>> but what about mysql.log, mysql.sock and mysql.pid
?
>> they must be in the shared disk or each node have
>> their own copy in /var/lib/mysq ?
> They should _not_ be on the shared disk. Some of
> them, such as mysql.pid, may even be used to
> check the status of the mysql resource.
>
> Dejan
Dejan, would please elaborate why the ".log", ".sock",
".pid" should not be on the shared disk ?
My reasoning is that if the shared (data) disk is
down, what difference does it make that the RA returns
an error saying it can not access the ".pid" file or
that the RA returns an error saying it can not acces
the data files ?
An argument in favor of having the ".pid" and ".log"
(the ".sock" being the exception as it is solely used
for local communication) on the same disk is that, in
essence, for a given instance, these files should be
*unique*, whatever the host the instance is running
on.
If this appears more self-evident for the ".log" file,
for the pid file, it is precisely because there is no
pid file, and some other conditions, that a RA on a
node taking over a failed node, can assert that an
instance was cleanly stopped.
If each node has it's own ".pid" file for one same
instance on local storage, there is no way the other
nodes can access the .pid file on a node that has just
failed. This may not appear as immediately critical,
but it becomes critical when the failing node with the
leftover pid file is bound to take over an instance.
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