[Lustre-discuss] Restoration of mds is of a different size!

[Jason Brooks]

Hello,

I am currently using lustre 1.8.  I am relatively new with lustre.  At the moment, I am trying to move an mds/mgs system from one disk to another.

I used the version of tar modified by whamcloud in order to dump and restore the filesytem.  I used mkfs.lustre to create a new mds/mgs filesystem on my /dev/sdc.  I then I mounted the old mds at /mnt/mdsold and the new mds at /mnt/mdsnew using filesystem type "ldiskfs"

I replicated the filesystem with the following command sequence:

cd /mnt/mdsold && tar —sparse —xattrs –cf - . | (cd /mnt/mdsnew && tar —sparse —xattrs –xvpf -)

However, look at the output of df:

Filesystem            Size  Used Avail Use% Mounted on
/dev/sdd              2.3T  7.9G  2.1T   1% /mnt/mdsold
/dev/sdc              815G  3.1G  765G   1% /mnt/mdsnew


Now, why would the new filesystem use 3.1 gigabytes when the old one takes up 7.9G?

=======================

Side note question: I have used the same version of tar to get a file-level backup of my mds:

tar —xattrs —sparse –cf - . >sdd.tar

The file created was 61 gigabytes in size.

Filesystem            Size  Used Avail Use% Mounted on
/dev/sdd              2.3T  7.9G  2.1T   1% /mnt/mdsold

Why is this?  Do the attributes take up extra space?

Thanks!
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