[Pvfs2-developers] host id

[Sam Lang]

Walt,

I think for your purposes you should probably just have each server/fs  
generate a uuid.  Keep in mind that everything (including the endpoint  
string and handle ranges) can change in the config file without  
recreating the storage spaces.  This often happens when admins want to  
migrate to other servers.

It might help to think about the storage space (and each fs within  
them) as the thing you want to reference with a permanent globally  
unique-id.  Our servers just manage those storage spaces, and the  
endpoint strings just provide an address (which can change over time).

If you were to use a uuid for each server/fs, you probably want random  
instead of time/host-based, so that you can move servers around  
without making the id invalid.  If you wanted them in the config file,  
they could be part of the Alias mapping, and genconfig could just  
generate them with uuidgen or something.  We've talked about having  
something like this for zero-conf, although that was more transient on  
a per-server start basis, to provide a consistent view if the config  
changed -- so a different purpose.

Alternatively, if that's all too over the top, and you just want an  
integer instead of a string, the index into the server list is no  
worse than the endpoint string.

-sam


On May 15, 2008, at 1:23 PM, Rob Ross wrote:

> Yes, having multiple file systems would really mess with you because  
> you could have the same handle for more than one FS. You sure you  
> don't want to just use a string name?
>
> Rob
>
> On May 15, 2008, at 1:10 PM, Nicholas Mills wrote:
>> Thanks for your help everyone.
>>
>> David and I have decided to use the first handle in the server's  
>> mapping to identify the server. We are at the point now where we  
>> need to find a handle range given a host alias. Does anyone know of  
>> a quick and easy way to do this?
>>
>> There is also the question of which handle range to use. Do we use  
>> the meta handles or the data handles? Also, will having multiple  
>> filesystems complicate anything?
>>
>> --Nick
>>
>> On Tue, May 13, 2008 at 4:10 PM, Phil Carns <carns at mcs.anl.gov>  
>> wrote:
>> I don't think we have any globally valid fixed sized identifier for  
>> the servers.  The only option I know if would be to use a handle  
>> (for example, the first handle in the server's mapping) to  
>> represent each server.  I think just using the string name would be  
>> safer, though.
>>
>> -Phil
>>
>>
>> Walter Ligon wrote:
>> Hey guys,
>>
>> we're needing to send a server host identification on the wire.  In  
>> the config the host_id appears to be a variable length string.   
>> Should we just use that, or is there something else of fixed size  
>> I'm not aware of?
>>
>> Walt
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