I believe if you do the following: Run Step 1 as described. Unmount Mount on secondary MDS (no reformat), you should be OK. Remember that an MGS can be on two completely separate devices from an MDT, so there's no direct relationship between the --mgsnode switches and the --failnode switch. When you try the format on the secondary MDS (2.1), you specify the address of the secondary MDS as the failnode, and when you mount it, it's also the primary node, so it's set to over to itself. If I had to guess the MGS sees that a new MDT is trying to register for the first time on it's failover node, and rejects the whole thing (same happens with OSTs).

I think this is just an initialization issue, it could be fixed with an optional --primary switch (or something).

------------------------------------------------------------------------ *From:* hpdd-discuss-bounces(a)lists.01.org <hpdd-discuss-bounces(a)lists.01.org&gt; on behalf of Swapnil Pimpale <spimpale(a)ddn.com&gt; *Sent:* Tuesday, August 27, 2013 9:28 AM *To:* hpdd-discuss(a)lists.01.org *Subject:* [HPDD-discuss] MDT mount fails if mkfs.lustre is run with multiple mgsnode arguments on MDSs where MGS is not running Hi All, We are facing the following issue. There is a JIRA ticket opened for the same (https://jira.hpdd.intel.com/browse/LU-3829) The description from the bug is as follows: If multiple --mgsnode arguments are provided to mkfs.lustre while formatting an MDT, then the mount of this MDT fails on the MDS where the MGS is not running. Reproduction Steps: Step 1) On MDS0, run the following script: mgs_dev='/dev/mapper/vg_v-mgs' mds0_dev='/dev/mapper/vg_v-mdt' mgs_pri_nid='10.10.11.210@tcp1' mgs_sec_nid='10.10.11.211@tcp1' mkfs.lustre --mgs --reformat $mgs_dev mkfs.lustre --mgsnode=$mgs_pri_nid --mgsnode=$mgs_sec_nid --failnode=$mgs_sec_nid --reformat --fsname=v --mdt --index=0 $mds0_dev mount -t lustre $mgs_dev /lustre/mgs/ mount -t lustre $mds0_dev /lustre/v/mdt So the MGS and MDT0 will be mounted on MDS0. Step 2.1) On MDS1: mdt1_dev='/dev/mapper/vg_mdt1_v-mdt1' mdt2_dev='/dev/mapper/vg_mdt2_v-mdt2' mgs_pri_nid='10.10.11.210@tcp1' mgs_sec_nid='10.10.11.211@tcp1' mkfs.lustre --mgsnode=$mgs_pri_nid --mgsnode=$mgs_sec_nid --failnode=$mgs_pri_nid --reformat --fsname=v --mdt --index=1 $mdt1_dev # Does not mount. mount -t lustre $mdt1_dev /lustre/v/mdt1 The mount of MDT1 will fail with the following error: mount.lustre: mount /dev/mapper/vg_mdt1_v-mdt1 at /lustre/v/mdt1 failed: Input/output error Is the MGS running? These are messages from Lustre logs while trying to mount MDT1: LDISKFS-fs (dm-20): mounted filesystem with ordered data mode. quota=on. Opts: LDISKFS-fs (dm-20): mounted filesystem with ordered data mode. quota=on. Opts: LDISKFS-fs (dm-20): mounted filesystem with ordered data mode. quota=on. Opts: Lustre: 7564:0:(client.c:1896:ptlrpc_expire_one_request()) @@@ Request sent has timed out for slow reply:[sent 1377197751/real 1377197751]req@ffff880027956c00 x1444089351391184/t0(0) o250->MGC10.10.11.210@tcp1@0@lo:26/25 lens 400/544 e 0 to 1 dl 1377197756 ref 1 fl Rpc:XN/0/ffffffff rc 0/-1 LustreError: 8059:0:(client.c:1080:ptlrpc_import_delay_req()) @@@ send limit expired req@ffff880027956800 x1444089351391188/t0(0) o253->MGC10.10.11.210@tcp1@0@lo:26/25 lens 4768/4768 e 0 to 0 dl 0 ref 2 fl Rpc:W/0/ffffffff rc 0/-1 LustreError: 15f-b: v-MDT0001: cannot register this server with the MGS: rc = -5. Is the MGS running? LustreError: 8059:0:(obd_mount_server.c:1732:server_fill_super()) Unable to start targets: -5 LustreError: 8059:0:(obd_mount_server.c:848:lustre_disconnect_lwp()) v-MDT0000-lwp-MDT0001: Can't end config log v-client. LustreError: 8059:0:(obd_mount_server.c:1426:server_put_super()) v-MDT0001: failed to disconnect lwp. (rc=-2) LustreError: 8059:0:(obd_mount_server.c:1456:server_put_super()) no obd v-MDT0001 LustreError: 8059:0:(obd_mount_server.c:137:server_deregister_mount()) v-MDT0001 not registered Lustre: server umount v-MDT0001 complete LustreError: 8059:0:(obd_mount.c:1277:lustre_fill_super()) Unable to mount (-5) Step 2.2) On MDS1: mdt1_dev='/dev/mapper/vg_mdt1_v-mdt1' mdt2_dev='/dev/mapper/vg_mdt2_v-mdt2' mgs_pri_nid='10.10.11.210@tcp1' mgs_sec_nid='10.10.11.211@tcp1' mkfs.lustre --mgsnode=$mgs_pri_nid --failnode=$mgs_pri_nid --reformat --fsname=v --mdt --index=1 $mdt1_dev mount -t lustre $mdt1_dev /lustre/v/mdt1 With this MDT1 will mount successfully. The only difference is that second "--mgsnode" is not provided during mkfs.lustre. Step 3: On MDS1 again: mkfs.lustre --mgsnode=$mgs_pri_nid --mgsnode=$mgs_sec_nid --failnode=$mgs_pri_nid --reformat --fsname=v --mdt --index=2 $mdt2_dev mount -t lustre $mdt2_dev /lustre/v/mdt2 Once MDT1 is mounted, then using a second "--mgsnode" option works without any errors and mount of MDT2 succeeds. Lustre Versions: Reproducible on 2.4.0 and 2.4.91 versions. Conclusion: Due to this bug, MDTs do not mount on MDSs that are not running the MGS. With the workaround, HA will not be properly configured. Also note that this issue is not related to DNE. Same issue and "workaround" applies to an MDT of a different filesystem on MDS1 as well. My initial thoughts on this are as follows: In the above case, while mounting an MDT on MDS1 one of the mgsnode is MDS1 itself. It looks like ptlrpc_uuid_to_peer() calculates the distance to NIDs using LNetDist() and chooses the one with the least distance. (which in this case turns out to be MDS1 itself which does not have a running MGS) Removing MDS1 from mgsnode and adding a different node worked for me. I would really appreciate any inputs on this. Thanks! -- Swapnil