[Gluster-users] Adding new volumes to DHT

[Moritz Krinke]

sorry, in my test they dont get distributed equally. the new volume  
gehts more files (all files with the same size).
How exactly the distribution algorithm works would be interesting?! :-)

Moritz

Am 22.07.2009 um 14:25 schrieb Moritz Krinke:

> Barry,
>
> i just did a test about that.
> if you add another subvolume to the DHT volume and add new files  
> into an existing directory they will be distributed over all DHT- 
> subvolumes.
>
> I assume that the distribution on old subvolumes will stop when the  
> free-space threshold is reached, but i did not test that.
>
> Moritz
>
>
> Am 21.07.2009 um 18:57 schrieb Barry Jaspan:
>
>> I have a question about this paragraph from the "Understanding DHT  
>> Translator":
>>
>> "Currently hash works based on directory level distribution. i.e, a  
>> given file's parent directory will have information of how the hash  
>> numbers are mapped to subvolumes. So, adding new node doesn't  
>> disturb any current setup as the files/dirs present already have  
>> its information preserved. Whatever new directory gets created,  
>> will start considering new volume for scheduling files."
>>
>> The last sentence suggests that if I have a single directory on a  
>> DHT volume and it is getting full, adding additional subvolumes to  
>> the DHT volume will not help because all the files in a directory  
>> will only ever live in subvolumes that existed at the time the  
>> directory is created.  Is that true?
>>
>> Also, it sounds like an entry mapping each filename (hash number)  
>> to a subvolume is stored in the extended attributes of the parent  
>> directory for that file.  What is the practical limit for the  
>> number of files that can be stored in a single directory under this  
>> system?  It seems like eventually doing a lookup in the directory's  
>> attributes would itself become a very expensive operation.
>>
>> Thanks,
>> Barry
>>
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>
>

Moritz Krinke
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