Lustre discuss - Oct 2006 - MDS files have been deleted,help needed

Dear all,

     I am using Lustre 1.4.6.2 on RHEL3.5 for the MDS/OSS and  the
clients.
      Everythings seems ok these months,but unfortunately,MDS data have been
deleted
by otherone yesterday.There are about 1.8TB data in the luster,it is a
disaster to us!
Can these data on OSS be possible recovried? or any other suggestion ?

thanks in advance

caven
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On Oct 03, 2006  06:38 +0800, ???? wrote:
>     I am using Lustre 1.4.6.2 on RHEL3.5 for the MDS/OSS and  the
> clients.
>      Everythings seems ok these months,but unfortunately,MDS data have been
> deleted
> by otherone yesterday.There are about 1.8TB data in the luster,it is a
> disaster to us!
> Can these data on OSS be possible recovried? or any other suggestion ?
If it was just the MDS that was erased (e.g. reformatted or something)
then the file data still resides on the OSTs.  If the files were deleted
from Lustre itself (i.e. a client) then it is very difficult to recover
the data.

If you are using the default 1 stripe per file, then you can mount the
OST filesystems directly like "mount -t ldiskfs /dev/XXXX /mnt/ost"
and
access the objects in O/0/d{0..31}, but you will not have any filename
information (which is on the MDS and presumably lost).  I believe that
1.4.6 OSTs may at least have user and group information on the objects.

In 1.4.7 newly-created objects have MDS inode information so that files
with multiple stripes could be reconstructed without MDS data.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2006/10/3, Andreas Dilger adilger@clusterfs.com:
>
>
> If it was just the MDS that was erased (e.g. reformatted or something)
> then the file data still resides on the OSTs.  If the files were deleted
> from Lustre itself (i.e. a client) then it is very difficult to recover
> the data.
>
> If you are using the default 1 stripe per file, then you can mount the
> OST filesystems directly like "mount -t ldiskfs /dev/XXXX
/mnt/ost" and
> access the objects in O/0/d{0..31}, but you will not have any filename
> information (which is on the MDS and presumably lost).  I believe that
> 1.4.6 OSTs may at least have user and group information on the objects.
>
> In 1.4.7 newly-created objects have MDS inode information so that files
> with multiple stripes could be reconstructed without MDS data.
>
> Cheers, Andreas
> --
> Andreas Dilger
> Principal Software Engineer
> Cluster File Systems, Inc.
>
> Thank you for the fast help.
Currently just the MDS files lost.
As you said,when mounted the OST filesystems
,there are many files in O/0/d{0..31} but no any
filename ,so it''s too hard to restor so many files with original
filenames
):
btw,how to reconstruct the files on the OSTs created in 1.4.7
without MDS data? I''ve created a luster with 1.4.7.1 to
do experiments,but on OSTs, the structure looks like previous version
(e.g. 1.4.6.2).

thanks again.
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On Oct 04, 2006  01:18 +0800, ???? wrote:
> 2006/10/3, Andreas Dilger adilger@clusterfs.com:
> >In 1.4.7 newly-created objects have MDS inode information so that files
> >with multiple stripes could be reconstructed without MDS data.
> 
> Currently just the MDS files lost.
> As you said,when mounted the OST filesystems
> ,there are many files in O/0/d{0..31} but no any
> filename ,so it''s too hard to restor so many files with original
filenames
> ):
Yes, this is the same as "lost+found" on a local filesystem if the
directory
is lost.
> btw,how to reconstruct the files on the OSTs created in 1.4.7
> without MDS data? I''ve created a luster with 1.4.7.1 to
> do experiments,but on OSTs, the structure looks like previous version
> (e.g. 1.4.6.2).
In 1.4.7 we get the added ability to recover files that are striped over
multiple OSTs.  With earlier versions the OST data is only really useful
if there are small files (< 1MB or whatever stripe size) or they are only
striped over a single file.

We still don''t have the ability to recover file names from the OST
data.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

Dear all,

     I am using Lustre 1.4.6.2 on RHEL3.5 for the MDS/OSS and  the
clients.
      Everythings seems ok these months,but unfortunately,MDS data have been
deleted
by otherone yesterday.There are about 1.8TB data in the luster,it is a
disaster to us!
Can these data on OSS be possible recovried? or any other suggestion ?

thanks in advance

caven
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