[lustre-discuss] lfs setstripe with stripe_count=0

[Andreas Dilger]

On Feb 21, 2023, at 10:26, John Bauer <bauerj at iodoctors.com<mailto:bauerj at iodoctors.com>> wrote:

Something doesn't make sense to me when using lfs setstripe when specifying 0 for the stripe_count .  This first command works as expected.  The pool is the one specified, 2_hdd, and the -c 0 results in a stripe_count of 1 which I believe is the default for the file-system default ( per the lfs setstripe manpage ).

pfe24.jbauer2 1224> lfs setstripe -c 0 -p 2_hdd /nobackupp18/jbauer2/testing/
pfe24.jbauer2 1225> lfs getstripe -d /nobackupp18/jbauer2/testing/
stripe_count:  1 stripe_size:   1048576 pattern:       raid0 stripe_offset: -1 pool:          2_hdd


If I do not specify the pool and only specify the stripe_count as 0, the resulting striping is what I believe is the pfl striping from the root directory of the file system.  Is this what is expected?  I would expect a stripe_count of 1, as above, with the pool from the parent directory's striping.

pfe24.jbauer2 1226> lfs setstripe -c 0 /nobackupp18/jbauer2/testing/

If you specify "-c 0" the "specified" file layout ends up being the same "all default values" as if nothing was specified for the layout at al (i.e. "-c 0 -i -1 -S 0")l, which results in the default filesystem layout being used.  If any non-default value is specified then the rest of the layout is filled in from the default values.

pfe24.jbauer2 1227> lfs getstripe -d /nobackupp18/jbauer2/testing/
  lcm_layout_gen:    0
  lcm_mirror_count:  1
  lcm_entry_count:   3
    lcme_id:             N/A
    lcme_mirror_id:      N/A
    lcme_flags:          prefer
    lcme_extent.e_start: 0
    lcme_extent.e_end:   268435456
      stripe_count:  1       stripe_size:   16777216 pattern:       raid0       stripe_offset: -1 pool:          ssd-pool

    lcme_id:             N/A
    lcme_mirror_id:      N/A
    lcme_flags:          prefer
    lcme_extent.e_start: 268435456
    lcme_extent.e_end:   5368709120
      stripe_count:  -1       stripe_size:   16777216 pattern:       raid0       stripe_offset: -1 pool:          ssd-pool

    lcme_id:             N/A
    lcme_mirror_id:      N/A
    lcme_flags:          0
    lcme_extent.e_start: 5368709120
    lcme_extent.e_end:   EOF
      stripe_count:  16       stripe_size:   16777216 pattern:       raid0       stripe_offset: -1 pool:          hdd-pool

pfe24.jbauer2 1228>

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Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Whamcloud







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