[gpfsug-discuss] how gpfs work when disk fail

Jan-Frode Myklebust janfrode at tanso.net
Mon Oct 9 14:45:32 BST 2017


You don't have room to write 180GB of file data, only ~100GB. When you
write f.ex. 90 GB of file data, each filesystem block will get one copy
written to each of your disks, occuppying 180 GB on total disk space. So
you can always read if from the other disks if one should fail.

This is controlled by your "-m 2 -r 2" settings, and the default
failureGroup -1 since you didn't specify a failure group in your disk
descriptor. Normally I would always specify a failure group when doing
replication.


  -jf


On Mon, Oct 9, 2017 at 2:47 PM, atmane khiredine <a.khiredine at meteo.dz>
wrote:

> dear all
>
> how gpfs work when disk fail
>
> this is a example scenario when disk fail
>
> 1 Server
>
> 2 Disk directly attached to the local node 100GB
>
> mmlscluster
>
> GPFS cluster information
> ========================
>   GPFS cluster name:         test.gpfs
>   GPFS cluster id:           174397273000001824
>   GPFS UID domain:           test.gpfs
>   Remote shell command:      /usr/bin/ssh
>   Remote file copy command:  /usr/bin/scp
>   Repository type:           server-based
>
> GPFS cluster configuration servers:
> -----------------------------------
>   Primary server:    gpfs
>   Secondary server:  (none)
>
>  Node  Daemon node name  IP address   Admin node name  Designation
> -------------------------------------------------------------------
>    1   gpfs         192.168.1.10    gpfs            quorum-manager
>
> cat disk
>
> %nsd:
>   device=/dev/sdb
>   nsd=nsda
>   servers=gpfs
>   usage=dataAndMetadata
>   pool=system
>
> %nsd:
>   device=/dev/sdc
>   nsd=nsdb
>   servers=gpfs
>   usage=dataAndMetadata
>   pool=system
>
> mmcrnsd -F disk.txt
>
> mmlsnsd -X
>
>  Disk name    NSD volume ID      Device     Devtype  Node name    Remarks
> ------------------------------------------------------------
> ---------------
>  nsdsdbgpfsa  C0A8000F59DB69E2   /dev/sdb   generic  gpfsa-ib   server node
>  nsdsdcgpfsa  C0A8000F59DB69E3   /dev/sdc   generic  gpfsa-ib   server node
>
>
> mmcrfs gpfs -F disk.txt -B 1M -L 32M -T /gpfs -A no -m 2 -M 3 -r 2 -R 3
>
> mmmount gpfs
>
> df -h
>
> gpfs   200G    3,8G  197G   2% /gpfs  <-- The Disk Have 200GB
>
> my question is the following ??
>
> if I write 180 GB of data in /gpfs
> and the disk /dev/sdb is fail
> how the disk and/or GPFS continues to support all my data
>
> Thanks
>
> Atmane Khiredine
> HPC System Administrator | Office National de la Météorologie
> Tél : +213 21 50 73 93 # 303 | Fax : +213 21 50 79 40 | E-mail :
> a.khiredine at meteo.dz
> _______________________________________________
> gpfsug-discuss mailing list
> gpfsug-discuss at spectrumscale.org
> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20171009/68fdf30f/attachment-0002.htm>


More information about the gpfsug-discuss mailing list