From netgridx at gmail.com  Tue Dec 10 08:56:52 2013
From: netgridx at gmail.com (pierce liu)
Date: Tue, 10 Dec 2013 16:56:52 +0800
Subject: [lustre-devel] question about mapping of file to object
Message-ID: <CAL0AMoperJKuFrFt=09fCt-M=eRJvHxO=woG_wv2reA0BPhC=Q@mail.gmail.com>

Hi,

I am a new beginner of lusterfs. During browsing the source code, I am
puzzled about how to map file to multi-object. Is there any document for
that, or how to trace the code.

BTW, is this mailing list the effective one for lusterfs, or we have other
list?

Thanks,
Pierce.
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From andreas.dilger at intel.com  Wed Dec 11 08:35:11 2013
From: andreas.dilger at intel.com (Dilger, Andreas)
Date: Wed, 11 Dec 2013 08:35:11 +0000
Subject: [lustre-devel] question about mapping of file to object
In-Reply-To: <CAL0AMoperJKuFrFt=09fCt-M=eRJvHxO=woG_wv2reA0BPhC=Q@mail.gmail.com>
References: <CAL0AMoperJKuFrFt=09fCt-M=eRJvHxO=woG_wv2reA0BPhC=Q@mail.gmail.com>
Message-ID: <CECD4EF5.84880%andreas.dilger@intel.com>

On 2013/12/10 1:56 AM, "pierce liu" <netgridx at gmail.com> wrote:
>I am a new beginner of lusterfs. During browsing the source code, I am
>puzzled about how to map file to multi-object. Is there any document for
>that, or how to trace the code.

Hi Pierce,
there is a general overview of Lustre at Wikipedia.  There are also quite
a few presentations available online, and videos on Youtube describing
the basics of Lustre.

The filesystem namespace is held on the MDT.  Each inode has a "Logical
Object Volume" (LOV) xattr (struct lov_mds_md_v1 or struct lov_mds_md_v3)
that describes the mapping to OST objects.  When a client opens a file on
the MDT, the LOV xattr is returned to the client, which describes they
layout of the file (stripe count, stripe size) and the OST objects that
hold the file data.  After that point, the client does IO directly to the
OSTs.

>BTW, is this mailing list the effective one for lusterfs, or we have
>other list?

This list is fine.

Cheers, Andreas
-- 
Andreas Dilger

Lustre Software Architect
Intel High Performance Data Division


From netgridx at gmail.com  Thu Dec 12 02:30:24 2013
From: netgridx at gmail.com (pierce liu)
Date: Thu, 12 Dec 2013 10:30:24 +0800
Subject: [lustre-devel] question about mapping of file to object
In-Reply-To: <CECD4EF5.84880%andreas.dilger@intel.com>
References: <CAL0AMoperJKuFrFt=09fCt-M=eRJvHxO=woG_wv2reA0BPhC=Q@mail.gmail.com>
	<CECD4EF5.84880%andreas.dilger@intel.com>
Message-ID: <CAL0AMooox26WiMbTv8KxdqcKuc-o=qJWTx-Do-G=ZV0rJih7hA@mail.gmail.com>

On Wed, Dec 11, 2013 at 4:35 PM, Dilger, Andreas
<andreas.dilger at intel.com>wrote:

> On 2013/12/10 1:56 AM, "pierce liu" <netgridx at gmail.com> wrote:
> >I am a new beginner of lusterfs. During browsing the source code, I am
> >puzzled about how to map file to multi-object. Is there any document for
> >that, or how to trace the code.
>
> Hi Pierce,
> there is a general overview of Lustre at Wikipedia.  There are also quite
> a few presentations available online, and videos on Youtube describing
> the basics of Lustre.
>
> Will see them.


> The filesystem namespace is held on the MDT.  Each inode has a "Logical
> Object Volume" (LOV) xattr (struct lov_mds_md_v1 or struct lov_mds_md_v3)
> that describes the mapping to OST objects.  When a client opens a file on
> the MDT, the LOV xattr is returned to the client, which describes they
> layout of the file (stripe count, stripe size) and the OST objects that
> hold the file data.  After that point, the client does IO directly to the
> OSTs.
>
>  Thanks for the clear explanation. I will trace the code and enjoy it.

>BTW, is this mailing list the effective one for lusterfs, or we have
> >other list?
>
> This list is fine.
>

I saw "linux-2.6/drivers/staging/lustre/TODO" , CCing hpdd-discuss <
hpdd-discuss at lists.01.org> would be great too.
So that list is just for linux-luster-client? Or add this mailling list on
the TODO too, so more people can be involved in?

Thanks and regards,
Pierce
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