[lustre-discuss] Lustre doesn't use new OST

[Massimo Sgaravatto]

Hi

We had a Lustre filesystem composed of 5 OSTs.
Because of a problem with 3 OSTs (the problem is described in the thread 
"Problems moving an OSS from an old Lustre installation to a new one"), 
we disabled them.

Now we want to reformat (mkfs.lustre --reformat ...) these 3 OSS and 
make them on-line.

For the time being we performed this operation just for one OSS (using a 
new index number).


The current scenario is the following (OST0005 is the reformatted OST):



lfs df -h /lustre/cmswork/
UUID                       bytes        Used   Available Use% Mounted on
cmswork-MDT0000_UUID      374.9G        3.5G      346.4G   1% 
/lustre/cmswork[MDT:0]
cmswork-OST0000_UUID       18.1T       14.5T        2.7T  84% 
/lustre/cmswork[OST:0]
cmswork-OST0001_UUID       18.1T       14.2T        3.0T  83% 
/lustre/cmswork[OST:1]
OST0002             : inactive device
OST0003             : inactive device
OST0004             : inactive device
cmswork-OST0005_UUID       13.6T      415.1M       12.9T   0% 
/lustre/cmswork[OST:5]

filesystem summary:        49.7T       28.7T       18.5T  61% 
/lustre/cmswork


The problem is that  the "Lustre scheduler" is not selecting OST0005 at 
all for new files.

Only if I use "lfs setstripe --index 5 " I see that the relevant files 
are written to this OST. Otherwise only OST0000 and OST0001 are used

We didn't change the values for qos_threshold_rr and qos_prio_free, 
which are therefore using the default values (17%, 91 %).


I can't find anything useful in the log files.
Any idea ?

Thanks, Massimo

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