[LU-12926] lfs mkdir -c can cause repeated MDT indexes Created: 01/Nov/19  Updated: 01/Nov/19

Status: Open
Project: Lustre
Component/s: None
Affects Version/s: Lustre 2.13.0, Lustre 2.12.3
Fix Version/s: None

Type: Bug Priority: Major
Reporter: Nathaniel Clark Assignee: Lai Siyao
Resolution: Unresolved Votes: 0
Labels: DNE

Issue Links:
Related
is related to LU-12273 DNE3: Metadata overstriping Open
Severity: 3
Rank (Obsolete): 9223372036854775807

 Description   

For a large (e.g. 5) number of MDTs, doing the following:

lfs mkdir -c 5 dir/

Can yield an MDT distribution of: {{4, 0, 4, 1, 2 }}or other distributions with repeated and missing mdt indexes.

Manually specifying mdts via -i works as expected.

I believe this is due to the "auto_distributed" logic in lustre/utils/lfs.c::lfs_setdirstripe()



 Comments   
Comment by Andreas Dilger [ 01/Nov/19 ]

It shouldn't be possible to do this with "-c", only when the metadata overstripingpatch adds the "-C" option.

Comment by Andreas Dilger [ 01/Nov/19 ]

We should add basic sanity checking on the MDS to avoid this. It should limit the stripe count to the number of available MDTs rather than return an error.

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