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List:       lustre-discuss
Subject:    Re: [lustre-discuss] [EXTERNAL] Converting MGS to ZFS - HA Config Question
From:       "Mohr, Rick via lustre-discuss" <lustre-discuss () lists ! lustre ! org>
Date:       2021-05-28 20:46:47
Message-ID: ED0A3102-D5C5-4FC5-8B44-7912540E082A () ornl ! gov
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Sid,

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.

-Rick


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

    Hi, 
    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 10.140.93.41@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 10.140.93.42 and the other MDS is \
10.140.93.41, 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=10.140.93.41@o2ib
    mkfs_cmd = zpool create -f -O canmount=off mgspool mirror d3710M0 d3710M1
    mkfs_cmd = zfs create -o canmount=off  mgspool/mgt
      xattr=sa
      dnodesize=auto
    Writing mgspool/mgt properties
      lustre:failover.node=10.140.93.41@o2ib
      lustre:version=1
      lustre:flags=100
      lustre:index=65535
      lustre:svname=MGS
    [root@hpc-mds-02]#


    ]# zfs list
    NAME          USED  AVAIL  REFER  MOUNTPOINT
    mgspool       468K   860G    96K  /mgspool
    mgspool/mgt    96K   860G    96K  /mgspool/mgt
    [root@hpc-mds-02 by-id]# zpool status
      pool: mgspool
     state: ONLINE
      scan: none requested
    config:

            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@hpc-mds-02#




    Sid Young

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