[Lustre-discuss] File joining mechanism

Lex lexluthor87 at gmail.com
Wed Jan 13 18:43:48 PST 2010


On Wed, Jan 13, 2010 at 5:40 PM, Tom.Wang <Tom.Wang at sun.com> wrote:

> Lex wrote:
>
>> Hi guys
>>
>> I have some questions about file joining mechanism in lustre, so i post
>> here and hope you can help me to clarify it :)
>>
>> As we know, lustre use the split writing and hierarchy striping to
>> distribute file object ( subfile)  to many osts in the cluster. When a
>> client request one file ( over mds metadata ), these objects are retrieve
>> from each ost to client.
>>
>> So, the question is: when and where these objects are joined together to
>> become a real file ?
>>
> File joining is actually joining the file stripe information.  which is
> stored in MDS, so the joining actually happens in MDS, instead of OSS.
>
>
Thank you for you fast reply, but i mean the physical joining file process,
not just information or metadata. As i know, file ( data ) doesn't go over
MDS, right ?  Sorry if i'm misunderstanding you


> Btw: Because of some reasons, joining file feature will be removed
> temporarily in lustre2.0.
>

Could you please tell me exactly what the reasons are ?


>
> Thanks
> WangDi
>
>>
>> Just guess, are there joined together in OSSs? If it's true, how these
>> OSSs connect together to join its objects together? ( For example, assuming
>> we have 2 OSSs, each OSS have 1 OST, file are striped across to 2 these
>> OSTs. When a client request a file, i get to object in 2 different OST from
>> 2 different OSSs, so how these objects can combined together? )
>>
>> Any help would be appreciated :)
>>
>> Many thanks
>>
>>
>>
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>>
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>
>
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