[lustre-discuss] lfs mirror create directory

[George Melikov]

Thank you, Jian, it works this way.

I want to read/write to Lustre even if one of OSTs with file is unavailable.

But now if i unmount one of OSTs with file, I can't read/write from/to this file.

Lustre v2.11.52

Is this use case works in Lustre?

# lfs getstripe ./1
./1
  lcm_layout_gen:    3
  lcm_mirror_count:  2
  lcm_entry_count:   2
    lcme_id:             65537
    lcme_mirror_id:      1
    lcme_flags:          init
    lcme_extent.e_start: 0
    lcme_extent.e_end:   EOF
      lmm_stripe_count:  1
      lmm_stripe_size:   1048576
      lmm_pattern:       raid0
      lmm_layout_gen:    0
      lmm_stripe_offset: 2
      lmm_objects:
      - 0: { l_ost_idx: 2, l_fid: [0x100020000:0x5:0x0] }

    lcme_id:             131074
    lcme_mirror_id:      2
    lcme_flags:          init,stale
    lcme_extent.e_start: 0
    lcme_extent.e_end:   EOF
      lmm_stripe_count:  1
      lmm_stripe_size:   1048576
      lmm_pattern:       raid0
      lmm_layout_gen:    0
      lmm_stripe_offset: 0
      lmm_objects:
      - 0: { l_ost_idx: 0, l_fid: [0x100000000:0x44:0x0] }
# umount /mnt/lustre/ost2
# cat ./1
...infinite wait...

So I've unmounted OST with index 2 and can't even `cat` the file.



28.09.2018, 20:17, "Jian Yu" <yujian at whamcloud.com>:
> Hi George,
>
> Please run "mkdir ./mirrored/" first, then run "lfs mirror create":
>
> # mkdir ./mirrored/
>
> # lfs mirror create -N2 ./mirrored/
>
> # lfs getstripe ./mirrored/
> ./mirrored/
>   lcm_layout_gen: 0
>   lcm_mirror_count: 2
>   lcm_entry_count: 2
>     lcme_id: N/A
>     lcme_mirror_id: N/A
>     lcme_flags: 0
>     lcme_extent.e_start: 0
>     lcme_extent.e_end: EOF
>       stripe_count: 1 stripe_size: 1048576 pattern: raid0 stripe_offset: -1
>
>     lcme_id: N/A
>     lcme_mirror_id: N/A
>     lcme_flags: 0
>     lcme_extent.e_start: 0
>     lcme_extent.e_end: EOF
>       stripe_count: 1 stripe_size: 1048576 pattern: raid0 stripe_offset: -1
>
> --
> Best regards,
> Jian Yu
>
> -----Original Message-----
> From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of George Melikov <mail at gmelikov.ru>
> Date: Friday, September 28, 2018 at 8:05 AM
> To: lustre-discuss <lustre-discuss at lists.lustre.org>
> Subject: [lustre-discuss] lfs mirror create directory
>
>     Does `lfs mirror create` work for directories in 2.11?
>     Tried it, nope :(
>
>     # lfs mirror create -N2 ./mirrored/
>     lfs mirror create: cannot create composite file './mirrored/': Is a directory
>
>     But documentation says it's good to go...
>     > lfs mirror create <--mirror-count|-N[mirror_count]
>     > [setstripe_options|[--flags<=flags>]]> ... <filename|directory>
>
>     ____________________________________
>     Sincerely,
>     George Melikov,
>