[lustre-discuss] lfs mirror create directory

[Jian Yu]

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,
     
     
     
    28.09.2018, 11:21, "Andreas Dilger" <adilger at whamcloud.com>:
    
    It is best to leave the MDT recordsize at the default. For most files it will not matter (too small), but for Data on MDT you also don't want a large recordsize. 
     
    Cheers, Andreas
    
    On Sep 28, 2018, at 09:17, Robert Redl <robert.redl at lmu.de> wrote:
     
    
    Dear All,
    I have a related question. The documentation says nothing about the recommended recordsize for MDTs with ZFS backend. Are there any recommendation? Or is data on MDTs stored in a way that the recordsize does not matter?
    Thanks,
    Robert
     
    On 09/28/2018 12:54 AM, Andreas Dilger wrote:
    
    Firstly, we don't test anything larger than 1MB.
     
    Secondly, the best recordsize is up to the apication IO pattern. If it is streaming writes, it might be OK. If it is random write then probably not. 
     
    Cheers, Andreas
    
    On Sep 27, 2018, at 19:04, Riccardo Veraldi <Riccardo.Veraldi at cnaf.infn.it> wrote:
     
    
    Hello,
    I have always been using ZFS record size to 1MB with Lustre on top of ZFS.  Anyway it is possible to set it to more than 1MB. May this have any benefit in performance and is it recommended to set for example:
    echo 4194304 > /sys/module/zfs/parameters/zfs_max_recordsize
    zfs set recordsize=4m zpool
    
    
    Thank you.
    Rick
     
    
    
    
    
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