[Pvfs2-developers] trove method

[Sam Lang]

On Oct 13, 2006, at 12:37 AM, Murali Vilayannur wrote:

> Hi Sam,
> Just one minor comment on the issue of specifying the trove method  
> in the config file..
> Can't we store the trove method names in the collections.db? We  
> already store the version string, right?
> If we do the above, then we can have mkspace take in a parameter  
> (command line) the dbpf method name which
> we can store it into the db without hardcoding anything..
> My 2 cents :)
>
Hi Murali,

I want to be able to support multiple trove methods with the same  
storage format, so switching from one to another makes sense if its  
just an option in the config file.  I could put the default in the  
collections.db, but I don't know what the default is, so it ends up  
pushing the hardcoding problem into the db.  Besides I think the dbpf  
method is needed to actually read the collections.db...  :-)

-sam

> otherwise looks good!
> Thanks,
> Murali
>>
>> I've attached a patch that provides support for different trove  
>> methods (currently we only have dbpf).  It also changes Phil's alt- 
>> aio implementation a little to be a separate trove method (using  
>> most of the dbpf code).
>>
>> The motivation for this is to allow multiple different trove  
>> methods to be supported, and switch easily from one to another.   
>> My next step is to modify Julian's version of dbpf that provides  
>> multiple threads support so that it works as a separate trove  
>> method as well.
>>
>> One issue I'm still not sure about:  I allowed the trove method to  
>> be specified as part of the Defaults context in the config file,  
>> as well as in each one of the Filesystem contexts (overrides the  
>> default).  The problem with specifying a different method for each  
>> filesystem is that the dbpf implementation stores info about the  
>> filesystems in the collections.db.  Does it make sense to only  
>> specify a trove method for the entire storage space?
>>
>> Also, there are some utilities (mkspace for example) that don't  
>> read in the config files, so they don't know what trove method has  
>> been specified.  Right now I'm just hardcoding the dbpf method,  
>> but that means that we can't really use a different trove method  
>> to provide a different storage format.  Not that we would ever  
>> want to...
>>
>> I'd like to commit this stuff sometime soon.  Please let me know  
>> if there are any objections or comments.
>>
>> Thanks,
>>
>> -sam
>>
>>
>>
>>
>>
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>