[Ocfs2-users] Two node performance question

[Sunil Mushran]

Bruce Leggett wrote:
>
> Hi,
>
> I’m new to OCFS2 and have a question about my setup. I have two SLES 
> 10 nodes (no patches yet) and a single OCFS2 volume. The volume 
> receives live data via replication to keep it up to date. The goal is 
> to have node one receive replicated date and all nodes run reports off 
> this date. Today I am just using two nodes to get started.
>
> The shared storage is an Openfiler 1.3 system running iscsi. Our 
> numbers for raw read and write look good.
>
> The problem is I am having an issue with keeping both nodes fast. If 
> node 1 is running reports quick, then node two is very bad and vise 
> versa.
>
> I’ve run hdparm –t /device on both nodes at the same time to see if I 
> get a drop off and it certainly does.
>
> Also, the bulk of the data is being written into /folder and all nodes 
> are reading out of that same folder at the same time. The files are 
> basically a slat file database that records are written into via one 
> node and read from all to be more specific. So a lot of SMALL writes 
> (one node) and many SMALL read (all nodes).
>
> I have no clue how to optimize this or if that is possible, if one 
> version will handle this better then another. We’re on base SLES 10 
> and I didn’t want to buy patches until I had some guidance.
>

If concurrent io to a shared device from multiple nodes is slow, then
the fs performance will also be slow. This will be true for any workload
and any file system. So ignore your workload for the time being and instead
work on improving the concurrent io thruput of your iscsi setup.