[Pvfs2-developers] PVFS2 Server- Dynamic FS Addition/Deletion

[Sam Lang]

Hi Hagai,

The server can remove/add storage spaces with trove function calls  
(it does this through the -f option at present), so that bit of  
functionality is already in-place.  There are still some other bits  
required though.

* The server needs to reload the config file, because it includes all  
the filesystem definitions.  This could be done by sending a SIGHUP  
signal to all the servers, and modifying the server's signal handling  
code to reload the config file on a SIGHUP.

* The clients retrieve config files from the servers with an  
operation called mgmt_getconfig.  The clients then cache the config  
files, so somehow that cache would have to be invalided.  We've  
talked about providing a unique version id with the config files  
returned by mgmt_getconfig, and then sending that version id with  
each operation made to the servers.  Once the version id didn't match  
on the server, it could return an error code that signaled the client  
to re-validate the config files with another call to mgmt_getconfig.

If you're willing to restart the clients (i.e. restart pvfs2-client),  
then you don't have to worry about the second bullet (which ends up  
being pretty complicated).  Clients pull the config files every time  
they're restarted.

If you need to know where some of the code is that does the different  
parts I mentioned, we can provide further details on all that.

-sam

On May 16, 2007, at 12:54 PM, Hagai Avrahami wrote:

> Hi
>
>
>
> I am trying to understand what changes need to be done in the code
>
> To support addition/deletion of file system in running pvfs2-server  
> without restart
>
>
>
> I will be grateful for any help I can get
>
> Thanx
>
> Hagai
>
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