Hi James,
there are the following spooling options if you want to setup sge_shadowd:
* classic spooling on nfs (or nfs4)
* Berkeley DB spooling on nfs4
* Berkeley DB RPC server (still available in Grid Engine 6.2u5, but
no longer supported with Univa Grid Engine 8.0.0)
With your current setup you can install sge_shadowd without changing
your spooling setup.
In deployments with a large number of hosts, many queues and esp. high
job throughput Berkeley DB spooling will give you better performance.
But switching the spooling method can not be done on the fly - this
would require re-installation of your cluster (could be done via
inst_sge -upd).
Regarding NFS4 on Linux: NFS4 support on older Linux versions is pretty
broken. But with current Linux versions NFS4 seems to be OK. We are
currently testing Berkeley DB spooling on NFS4 on Linux, so far with
good success.
In your case I would recommend sticking with classic spooling for now,
should you experience performance issues due to spooling, you might want
to switch to Berkeley DB.
Classic spooling should provide sufficient security (in has code to
prevent data corruption due to filesystem write errors), but Berkeley DB
will certainly provide higher security - it provides ACID (atomicity,
consistency, isolation, durability) criteria, see
http://en.wikipedia.org/wiki/ACID.
Best regards,
Joachim
James Abbott wrote:
Hello,
I'm in the process of reorganising our SGE setup, and would appreciate
some guidance on a couple of points re: spooling.
Our $SGE_ROOT is exported to all hosts from a separate clustered, highly
available NFS4 server. The qmaster is using classic spooling to
SGE_ROOT/spool/qmaster. I want to add a shadow master for improved
resilance, but have got a little confused over the 'best' way of
handling spooling for this setup.
I understood it was necessary to use a BDB spooling server if using
shadow masters, but see that this is essentially being deprecated due to
BDB RPC issues. I've also read that classic spooling is ok via nfs4
(hence our current setup...), but have since seen comments that this
only applies if the qmaster is running on Solaris (our SGE
infrastructure is all CentOS 5.5).
So, adding a BDB spooling server introduces RPC security weaknesses and
a single point of failure, and looks like will not be an option in
future releases so doesn't look like an ideal solution. The NFS server
currently hosting SGE_ROOT is a clustered, highly available system, so
gives us resiliance, but is using NFS4 for classic spooling really safe?
It seems to be working ok for us with a single qmaster, but that may be
due to luck...
Bottom line question: What is the optimal spooling setup for using
shadow masters?
If we do decide to move to a BDB server, can I setup the spooling server
and simply shutdown the qmaster, edit
$SGE_ROOT/$SGE_CELL/common/bootstrap and restart the qmaster, or is it
more involved than that?
Many thanks,
James
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