[Lustre-discuss] redistribute used space to other OSTs (free space)

[Brian J. Murrell]

On Tue, 2008-11-04 at 15:51 +0200, Alex wrote:
> [root at rs1 ~]# lfs df -h
> UUID                     bytes      Used Available  Use% Mounted on
> testfs-MDT0000_UUID     130.4G    460.1M    122.5G    0% /mnt/lustre[MDT:0]
> testfs-OST0000_UUID      18.3G     17.4G      2.0M   94% /mnt/lustre[OST:0]
> testfs-OST0001_UUID      18.3G     15.5G      2.0G   84% /mnt/lustre[OST:1]
> testfs-OST0002_UUID      36.7G     15.5G     19.4G   42% /mnt/lustre[OST:2]
> testfs-OST0003_UUID      36.7G     15.5G     19.4G   42% /mnt/lustre[OST:3]
> filesystem summary:     110.0G     63.8G     40.7G   57% /mnt/lustre
> [root at rs1 ~]#
> 
> As you can see OST:0 is full!

Indeed.  Is this a 1.6 or a 1.4 installation?  As long as you have not
forced an allocation policy with striping for example, with 1.6 your
OSTs should fill in a more-or-less even manner and you should not see
this type of problem.

> Question1: Is any command to use in order to move arround 60% of OST:0 data 
> from OST:0 to other OST or to all other OSTes (arround 20% to each other)?

Deactivate allocation to the full OST on the MDS and do some "mv" (or
cp/rm if you are more comfortable with that) operations which will
result in moving the objects for the file to other OSTs.

> Question2: How can i see larger objects (bigger then 100MB) stored on OST:0 

man lfs

The find option to lfs has all sorts of options for finding files on a
Lustre filesystem including some Lustre specific options.  You probably
want:

# lfs find /mnt/lustre -size +100M --obd testfs-OST0000_UUID

b.