[lustre-discuss] [EXTERNAL] Converting MGS to ZFS - HA Config Question

Mohr, Rick mohrrf at ornl.gov
Fri May 28 13:46:47 PDT 2021


The --failnode option is the sort of the "old way" of configuring failover.  It is assumed that the target will always be mounted for the first time on the primary server, and so the --failnode option only needs to list the secondary server NID (because the primary server NID is implied by whatever host mounts the target first).

The --servicenode option is the preferred way of configuring failover now.  It does not make any assumptions about primary/secondary nodes, but as a result, you need to specify the NIDs of all nodes that could possibly mount the target.  The easiest way to do this is to specify the "--servicenode <nid>" option multiple times (once for each node).

And as you have seen, the two options are not compatible with each other.


On 5/27/21, 11:53 PM, "lustre-discuss on behalf of Sid Young via lustre-discuss" <lustre-discuss-bounces at lists.lustre.org on behalf of lustre-discuss at lists.lustre.org> wrote:

    I am in the process of converting my pre-production cluster to use ZFS, and I have a question regarding HA config parameters. The storage node has 24 disks, I've sliced off two disks in HBA mode to act as a 960G mirror. the command is:
    # mkfs.lustre --reformat --mgs  --failnode at o2ib --backfstype=zfs mgspool/mgt mirror d3710M0 d3710M1
    This runs successfully and I get the output below, however I want to make sure the second MDS node can be failed over too using Pacemaker, so if the server I am on now is and the other MDS is, do I need to specify the host its on now (.42) anywhere in the config? I tried the servicenode parameter but it refuses to have servicenode and failnode in the command:

       Permanent disk data:
    Target:     MGS
    Index:      unassigned
    Lustre FS:
    Mount type: zfs
    Flags:      0x64
                  (MGS first_time update )
    Persistent mount opts:
    Parameters: failover.node= at o2ib
    mkfs_cmd = zpool create -f -O canmount=off mgspool mirror d3710M0 d3710M1
    mkfs_cmd = zfs create -o canmount=off  mgspool/mgt
    Writing mgspool/mgt properties
      lustre:failover.node= at o2ib
    [root at hpc-mds-02]#

    ]# zfs list
    mgspool       468K   860G    96K  /mgspool
    mgspool/mgt    96K   860G    96K  /mgspool/mgt
    [root at hpc-mds-02 by-id]# zpool status
      pool: mgspool
     state: ONLINE
      scan: none requested

            NAME         STATE     READ WRITE CKSUM
            mgspool      ONLINE       0     0     0
              mirror-0   ONLINE       0     0     0
                d3710M0  ONLINE       0     0     0
                d3710M1  ONLINE       0     0     0

    errors: No known data errors
    [root at hpc-mds-02#

    Sid Young

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