[Pvfs2-users] multiple filesystems

Becky Ligon ligon at clemson.edu
Mon Oct 25 15:56:46 EDT 2010

As it turns out, you shouldn't try to share out a PVFS directory.  PVFS
doesn't play well with NFS in that way.  After I wrote you about that, I
asked some others about it and discovered that you shouldn't do that. 
Sorry 'bout that!

Becky Ligon
PVFS Developer
Clemson University

> Becky-
> Thanks for the suggestion. We won't be doing much i/o on /home; mostly I
> just need it to be consistent across nodes on an expanding cluster.
> Could you explain how to share out the subdirectories like you mention
> at the end? I can't seem to directly mount a subdirectory like
> <path>/mount1/home, only <path>/mount1.
> Thanks,
> -crispy
> On 10/21/2010 03:14 PM, Becky Ligon wrote:
>> You can define two mountpoints in your pvfs2tab file, say<path>/mount1
>> and<path>/mount2, each pointing to the same tcp address and filesystem.
>> This way you can "share out" the different mount points.  However, the
>> data in<path>/mount1 and<path>/mount2 is being handled by the one set of
>> servers and resides in the same physical space, i.e.,<storage
>> path>/<filesystem ID>.  I know this works, because I tried it when I was
>> investigating the multiple ports/alias for you.
>> While Kevin is working on a bug fix for you, try changing your fs.conf
>> file to have only one filesystem.  Re-create your storage space.  Setup
>> your pvfs2tab file with two entires, one for mount1 and one for mount2.
>> See if you can't create files using either mount point.
>> With this approach, an ls on<path>/mount1 and an ls on<path>/mount2 will
>> show the same entries.  You might try creating two directories,
>> <path>/mount1/home and<path>/mount2/scratch, and "share out"
>> <path>/mount1/home as /home and<path>/mount2/scratch as /scratch;
>> however, I think PVFS doesn't perform well in this situation.  In fact,
>> PVFS is not intended for a lot of small-io.  You might want to make
>> /home,
>> a regular ext3 (or whatever) directory and let /scratch be a PVFS
>> filesystem to be used only for large outputs.
>> Becky

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