[Lustre-discuss] removing ost

[Thomas Roth]

Hi Marc,

you could unmount that OST and mount it again with "-t ldiskfs", so you can have a look inside. I think the data objects are in /mountpoint/O/0/d*,
and a listing shows you the ownership of the remaining files. That might give you a clue as to which directory in you Lustre you should rescan with
"lfs find".
This helped me a number of times.
However, in some cases there were  Gigabytes left that didn't show up with "lfs find". I guess these were lost objects from some crashes that had
occurred in the past. Nobody missed those files, so no problem.

Yours,
Thomas

On 03/23/2012 10:15 AM, Marc Boisis-Delavaud wrote:
> Hello,
> I want to remove an ost from my lustre filsystem. My version is 1.8.4.
> 
> I've deactivated home-OST0004 on my mds
> lctl > dl
>   0 UP mgc MGC10.149.0.2 at o2ib d00cdda9-5757-d58d-c5a5-073225015995 5
>   1 UP mdt MDS MDS_uuid 3
>   2 UP lov home-mdtlov home-mdtlov_UUID 4
>   3 UP mds home-MDT0000 home-MDT0000_UUID 89
>   4 IN osc home-OST0004-osc home-mdtlov_UUID 5
>   5 UP osc home-OST0003-osc home-mdtlov_UUID 5
>   6 UP osc home-OST0002-osc home-mdtlov_UUID 5
>   7 UP osc home-OST0001-osc home-mdtlov_UUID 5
>   8 UP osc home-OST0000-osc home-mdtlov_UUID 5
>   9 UP lov scratch-mdtlov scratch-mdtlov_UUID 4
>  10 UP mds scratch-MDT0000 scratch-MDT0000_UUID 85
>  11 UP mgs MGS MGS 91
>  12 UP osc scratch-OST0000-osc scratch-mdtlov_UUID 5
> 
> 
>>From a client I've made : lfs find --obd home-OST0004_UUID /Recherche | lfs_migrate -y
> 
> Most of the files have been moved to the others OST but now the "lfs find --obd home-OST0004_UUID /Recherche"  find nothing but the home-OST0004  is not empty !
> 
>  # lfs df -i
> UUID                      Inodes       IUsed       IFree IUse% Mounted on
> home-MDT0000_UUID       24275160     5268561    19006599  21% /Recherche[MDT:0]
> home-OST0000_UUID      335544320     2627858   332916462   0% /Recherche[OST:0]
> home-OST0001_UUID      335544320      673756   334870564   0% /Recherche[OST:1]
> home-OST0002_UUID      335544320      917063   334627257   0% /Recherche[OST:2]
> home-OST0003_UUID      335544320      927120   334617200   0% /Recherche[OST:3]
> home-OST0004_UUID      335544320         560   335543760   0% /Recherche[OST:4]
> filesystem summary:     24275160     5268561    19006599  21% /Recherche
> 
> # lfs df  -h
> UUID                       bytes        Used   Available Use% Mounted on
> home-MDT0000_UUID          81.0G        1.1G       75.3G   1% /Recherche[MDT:0]
> home-OST0000_UUID           4.9T        2.0T        2.7T  39% /Recherche[OST:0]
> home-OST0001_UUID           4.9T        1.0T        3.7T  20% /Recherche[OST:1]
> home-OST0002_UUID           4.9T        1.4T        3.3T  28% /Recherche[OST:2]
> home-OST0003_UUID           4.9T        1.3T        3.3T  27% /Recherche[OST:3]
> home-OST0004_UUID           4.9T      480.0M        4.7T   0% /Recherche[OST:4]
> 
> filesystem summary:        24.6T        5.7T       17.7T  23% /Recherche
> 
> 
> 
> How can I see what stay on home-OST0004  ?
> 
> 
> 
> 
> 
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Thomas Roth
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