Re: re-export NFS mounted disk to be NFS mounted?

Thank for the explaining, Yuri.

Our cluster mainly is computational, not much disk activity, so I  
guess I will do the NFS thing.

CY


On Mar 23, 2009, at 1:23 PM, Yuri Csapo wrote:

> Well, a lot of it depends on the hardware you have, but re-exporting  
> is really not a good idea no matter which protocol you use. Unless  
> the cluster is a computational cluster which only needs to read/ 
> write disks sporadically, I'd strongly suggest you give it its own  
> disk space, directly attached to the head node (or use a SAN, but  
> that's beside the scope here I think).
>
> We have a number of clusters here and there are 2 different  
> solutions we use (that I'm aware of):
>
> - For the big supercomputer we use a SAN which all nodes can see  
> with Lustre as a filesystem. You can see hardware details here:
>
> http://geco.mines.edu/hardware.shtml
>
> - For small clusters (typically 10-node) we use disks directly  
> attached to the head and NFS-exported to the nodes. This is just one  
> hop of NFS so it's not that bad; still we work around it (after a  
> fashion) by having local disks on each node that can be used as a  
> temporary, node-specific scratch area.
>
> Hope this helps...
>
> Yuri
>
> Yu Chen wrote:
>> Thanks Yuri,
>> Other than NFS, what else can I do, I heard a lot about NFS's  
>> performance, but I just don't know an alternative yet (AFP doesn't  
>> work that well on a server as what I read from mail lists, and from  
>> trying).
>> Guess I will go to local disk solution.
>> CY
>> On Mar 23, 2009, at 12:15 PM, Yuri Csapo wrote:
>>> AFAIK that is not possible on Linux with the stock kernel nfs  
>>> server. It *should*  be possible with the userspace server, but  
>>> I'm not sure it's supported. Maybe someone who has actually done  
>>> it (as opposed to playing with it) should comment.
>>>
>>> OTOH it doesn't seem like a good idea anyway... NFS's performance  
>>> is really bad and what you're doing will multiply bad x 2. I know  
>>> sometimes you need to work with what you have but if your cluster  
>>> is in any way I/O sensitive you should think about getting some  
>>> local disk space for it, at least.
>>>
>>> Yu Chen wrote:
>>>> Hello,
>>>> I have a cluster, the disk space is on a Xserver, it's NFS  
>>>> exported, and mounted on the cluster's head node without problem  
>>>> (mounted on /mnt/nfs), then I exported the "/mnt/nfs" directory,  
>>>> then tried to mount it on the nodes in the cluster (mount -t nfs  
>>>> headnode:/mnt/nfs /mnt/tmp), it gave error: mount ... failed,  
>>>> reason given by server: Permission denied.
>>>> my Xserver nfs exports entry has this: /Volumes/DataRAID  - 
>>>> alldirs -maproot=nobody -sec=sys -network my.headnode.network - 
>>>> mask 255.255.255.0
>>>> my headnode mounted /Volumes/DataRAID on /mnt/nfs then exported  
>>>> as nfs exports entry:
>>>> /mnt/nfs 10.0.0.0/255.255.255.0(rw,sync)
>>>> Anybody has any suggestions?
>>>> Thanks in advance.
>>>> CY
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>>>
>>> -- 
>>> Yuri Csapo
>>> Academic Computing & Networking
>>> Colorado School of Mines
>>> CT-256
>>> Phone:  (303) 273-3503
>>> Fax:      (303) 273-3475
>>> Email:   [email protected]
>>>
>>> Please use the following link to open a service request:
>>> http://helpdesk.mines.edu
>>> ===========================================
>>> With a PC, I always felt limited
>>> by the software available.
>>> On Unix, I am limited only by my knowledge.
>>> --Peter J. Schoenster
>>>
>
> -- 
> Yuri Csapo
> Academic Computing & Networking
> Colorado School of Mines
> CT-256
> Phone:  (303) 273-3503
> Fax:      (303) 273-3475
> Email:   [email protected]
>
> Please use the following link to open a service request:
> http://helpdesk.mines.edu
> ===========================================
> With a PC, I always felt limited
> by the software available.
> On Unix, I am limited only by my knowledge.
> --Peter J. Schoenster
>