You'll probably need to refer to this page (and the wiki link there) for
the latest pNFS information:
http://www.citi.umich.edu/projects/asci/pnfs/linux/
thanks,
-Phil
Nirmal Thacker wrote:
Hi Phil,
Yes, I recently learned that having multiple pNFS MDS servers are not
possible.
Has there been some work [either some benchmarks/new design] in this
direction?
Thanks
Nirmal
Phil Carns wrote:
Hi Nirmal,
Are you trying to have multiple pNFS MDS servers, or multiple meta
servers in the PVFS volume?
I don't believe that the former is supported (but I was hoping someone
else would chime in- I have not used the pNFS/PVFS implementation
first hand).
The latter should work fine without any particular changes to the
installation steps except for the PVFS configuration files.
In either case I am pretty sure that the bind option to mount is not
going to do what you are looking for.
-Phil
Nirmal Thacker wrote:
Hello,
I have a question regarding CITI's implementation of pNFS/PVFS2
Alternatively you could point me to a mailing lists for users of
pNFS/PVFS2 by the CITI group. I cannot seem to find a forum/group who
discuss issues of pNFS/PVFS2 [if it is not this one]
My problem is as follows:
I want to use more than a single Metadata server [MDS] in CITI's
pNFS/PVFS2. I use the instructions described here:
http://www.citi.umich.edu/projects/asci/pnfs/docs/pnfspvfs2.html
I understand these are not of the current build, but I am using an older
build of pNFS/PVFS2.
Now if there are two or more MDS nodes, then how will clients mount the
MDS nodes on a single mount point? I am familiar with the mount --bind
argument
[http://www.redhatmagazine.com/2007/03/19/how-do-i-mount-an-nfsv4-filesystem-in-two-locations-on-a-single-client/].
Is this what we must do?
This situation arises on two occasions
1. When the MDS mounts a PVFS2 filesystem. Multiple MDS then mount the
MDS PVFS2 filesystems at one point.
To quote from the instructions :
// Load kernel interface
// Run on MDS
insmod /usr/local/bin/pvfs2-server/pvfs2.ko
/usr/local/bin/pvfs2-server/sbin/pvfs2-client -p
/usr/lo:cal/bin/pvfs2-server/sbin/pvfs2-client-core
mount -t pvfs2 tcp://"mds_server_hostname":3334/pvfs2-fs /mnt/pvfs2
2. When the clients mount an NFS4 filesystem [essentially a PVFS2
filesystem exported by the MDS]
To quote:
Step 7: Mount PVFS2 file system using pNFS
* Copy /etc/pvfs2tab file to every client
* Example:
// On client
insmod /usr/local/bin/pvfs2-layout/pvfs2-pnfs.ko
/usr/local/bin/pvfs2-layout/sbin/pvfs2-client -p
/usr/local/bin/pvfs2-layout/sbin/pvfs2-client-core
mount -t nfs4 "mds_server_name":/ /mnt/nfs4/
In both cases, multiple MDS cause the mounts to overlap. Although I have
not tried this out, I suspect this is would result in an incorrect
configuration.
Have you come across this issue when you worked with pNFS/PVFS2 before?
Thanks for your time.
Nirmal Thacker
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