[lustre-discuss] Lustre/ZFS snapshots mount error
Robert Redl
robert.redl at lmu.de
Sat Sep 8 06:03:41 PDT 2018
Dear All,
we have a similar setup with Lustre on ZFS and we make regular use of
snapshots for the purpose of backups (backups on tape use snapshots as
source). We would like to use robinhood in future and the question is
now how to do it.
Would it be a workaround to disable the robinhood daemon temporary
during the mount process?
Does the problem only occur when changelogs are consumed during the
process of mounting a snapshot? Or is it also a problem when changelogs
are consumed while the snapshot remains mounted (which is for us
typically several hours)?
Is there already an LU-ticket about this issue?
Thanks!
Robert
--
Dr. Robert Redl
Scientific Programmer, "Waves to Weather" (SFB/TRR165)
Meteorologisches Institut
Ludwig-Maximilians-Universität München
Theresienstr. 37, 80333 München, Germany
Am 03.09.2018 um 08:16 schrieb Yong, Fan:
>
> I would say that it is not your operations order caused trouble.
> Instead, it is related with the snapshot mount logic. As mentioned in
> former reply, we need some patch for the llog logic to avoid modifying
> llog under snapshot mode.
>
>
>
>
>
> --
>
> Cheers,
>
> Nasf
>
> *From:*Kirk, Benjamin (JSC-EG311) [mailto:benjamin.kirk at nasa.gov]
> *Sent:* Tuesday, August 28, 2018 7:53 PM
> *To:* lustre-discuss at lists.lustre.org
> *Cc:* Andreas Dilger <adilger at whamcloud.com>; Yong, Fan
> <fan.yong at intel.com>
> *Subject:* Re: [lustre-discuss] Lustre/ZFS snapshots mount error
>
>
>
> The MDS situation is very basic: active/passive mds0/mds1 for both fas
> & fsB. fsA has the combined msg/mdt in a single zfs filesystem, and
> fsB has its own mdt in a separate zfs filesystem. mds0 is primary for
> all.
>
>
>
> fsA & fsB DO both have changelogs enabled to feed robinhood databases.
>
>
>
> What’s the recommended procedure here we should follow before mounting
> the snapshots?
>
>
>
> 1) disable changelogs on the active mdt’s (this will compromise
> robinhood, requiring a rescan…), or
>
> 2) temporarily halt changelog consumption / cleanup (e.g. stop
> robinhood in our case) and then mount the snapshot?
>
>
>
> Thanks for the help!
>
>
>
> --
>
> Benjamin S. Kirk, Ph.D.
>
> NASA Lyndon B. Johnson Space Center
>
> Acting Chief, Aeroscience & Flight Mechanics Division
>
>
>
> On Aug 27, 2018, at 7:33 PM, Yong, Fan <fan.yong at intel.com
> <mailto:fan.yong at intel.com>> wrote:
>
>
>
> According to the stack trace, someone was trying to cleanup old
> empty llogs during mount the snapshot. We do NOT allow any
> modification during mount snapshot; otherwise, it will trigger ZFS
> backend BUG(). That is why we add LASSERT() when start the
> transaction. One possible solution is that, we can add some check
> in the llog logic to avoid modifying llog under snapshot mode.
>
>
> --
> Cheers,
> Nasf
>
> -----Original Message-----
> From: lustre-discuss
> [mailto:lustre-discuss-bounces at lists.lustre.org] On Behalf Of
> Andreas Dilger
> Sent: Tuesday, August 28, 2018 5:57 AM
> To: Kirk, Benjamin (JSC-EG311) <benjamin.kirk at nasa.gov
> <mailto:benjamin.kirk at nasa.gov>>
> Cc: lustre-discuss at lists.lustre.org
> <mailto:lustre-discuss at lists.lustre.org>
> Subject: Re: [lustre-discuss] Lustre/ZFS snapshots mount error
>
> It's probably best to file an LU ticket for this issue.
>
> It looks like there is something with the log processing at mount
> that is trying to modify the configuration files. I'm not sure
> whether that should be allowed or not.
>
> Does fab have the same MGS as fsA? Does it have the same MDS node
> as fsA?
> If it has a different MDS, you might consider to give it its own
> MGS as well.
> That doesn't have to be a separate MGS node, just a separate
> filesystem (ZFS fileset in the same zpool) on the MDS node.
>
> Cheers, Andreas
>
>
> On Aug 27, 2018, at 10:18, Kirk, Benjamin (JSC-EG311)
> <benjamin.kirk at nasa.gov <mailto:benjamin.kirk at nasa.gov>> wrote:
>
> Hi all,
>
> We have two filesystems, fsA & fsB (eadc below). Both of
> which get snapshots taken daily, rotated over a week. It’s a
> beautiful feature we’ve been using in production ever since it
> was introduced with 2.10.
>
> -) We’ve got Lustre/ZFS 2.10.4 on CentOS 7.5.
> -) Both fsA & fsB have changelogs active.
> -) fsA has combined mgt/mdt on a single ZFS filesystem.
> -) fsB has a single mdt on a single ZFS filesystem.
> -) for fsA, I have no issues mounting any of the snapshots via
> lctl.
> -) for fsB, I can mount the most three recent snapshots, then
> encounter errors:
>
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_mount -F eadc -n
> eadc_AutoSS-Mon
> mounted the snapshot eadc_AutoSS-Mon with fsname 3d40bbc
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_umount -F eadc -n
> eadc_AutoSS-Mon
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_mount -F eadc -n
> eadc_AutoSS-Sun
> mounted the snapshot eadc_AutoSS-Sun with fsname 584c07a
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_umount -F eadc -n
> eadc_AutoSS-Sun
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_mount -F eadc -n
> eadc_AutoSS-Sat
> mounted the snapshot eadc_AutoSS-Sat with fsname 4e646fe
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_umount -F eadc -n
> eadc_AutoSS-Sat
> [root at hpfs-fsl-mds0 ~]# lctl snapshot_mount -F eadc -n
> eadc_AutoSS-Fri
> mount.lustre: mount metadata/meta-eadc at eadc_AutoSS-Fri at
> /mnt/eadc_AutoSS-Fri_MDT0000 failed: Read-only file system
> Can't mount
> the snapshot eadc_AutoSS-Fri: Read-only file system
>
> The relevant bits from dmesg are
> [1353434.417762] Lustre: 3d40bbc-MDT0000: set dev_rdonly on this
> device [1353434.417765] Lustre: Skipped 3 previous similar
> messages
> [1353434.649480] Lustre: 3d40bbc-MDT0000: Imperative Recovery
> enabled,
> recovery window shrunk from 300-900 down to 150-900
> [1353434.649484]
> Lustre: Skipped 3 previous similar messages [1353434.866228]
> Lustre:
> 3d40bbc-MDD0000: changelog on [1353434.866233] Lustre: Skipped 1
> previous similar message [1353435.427744] Lustre:
> 3d40bbc-MDT0000:
> Connection restored to ... at tcp <mailto:... at tcp> (at ... at tcp
> <mailto:... at tcp>) [1353435.427747] Lustre:
> Skipped 23 previous similar messages [1353445.255899] Lustre:
> Failing
> over 3d40bbc-MDT0000 [1353445.255903] Lustre: Skipped 3 previous
> similar messages [1353445.256150] LustreError: 11-0:
> 3d40bbc-OST0000-osc-MDT0000: operation ost_disconnect to node
> ... at tcp <mailto:... at tcp>
> failed: rc = -107 [1353445.257896] LustreError: Skipped 23
> previous
> similar messages [1353445.353874] Lustre: server umount
> 3d40bbc-MDT0000 complete [1353445.353877] Lustre: Skipped 3
> previous
> similar messages [1353475.302224] Lustre: 4e646fe-MDD0000:
> changelog
> on [1353475.302228] Lustre: Skipped 1 previous similar message
> [1353498.964016] LustreError:
> 25582:0:(osd_handler.c:341:osd_trans_create())
> 36ca26b-MDT0000-osd: someone try to start transaction under
> readonly mode, should be disabled.
> [1353498.967260] LustreError:
> 25582:0:(osd_handler.c:341:osd_trans_create()) Skipped 1
> previous similar message
> [1353498.968829] CPU: 6 PID: 25582 Comm: mount.lustre Kdump:
> loaded Tainted: P OE ------------
> 3.10.0-862.6.3.el7.x86_64 #1
> [1353498.968830] Hardware name: Supermicro
> SYS-6027TR-D71FRF/X9DRT,
> BIOS 3.2a 08/04/2015 [1353498.968832] Call Trace:
> [1353498.968841] [<ffffffffb5b0e80e>] dump_stack+0x19/0x1b
> [1353498.968851] [<ffffffffc0cbe5db>]
> osd_trans_create+0x38b/0x3d0
> [osd_zfs] [1353498.968876] [<ffffffffc1116044>]
> llog_destroy+0x1f4/0x3f0 [obdclass] [1353498.968887]
> [<ffffffffc111f0f6>] llog_cat_reverse_process_cb+0x246/0x3f0
> [obdclass] [1353498.968897] [<ffffffffc111a32c>]
> llog_reverse_process+0x38c/0xaa0 [obdclass] [1353498.968910]
> [<ffffffffc111eeb0>] ? llog_cat_process_cb+0x4e0/0x4e0 [obdclass]
> [1353498.968922] [<ffffffffc111af69>]
> llog_cat_reverse_process+0x179/0x270 [obdclass] [1353498.968932]
> [<ffffffffc1115585>] ? llog_init_handle+0xd5/0x9a0 [obdclass]
> [1353498.968943] [<ffffffffc1116e78>] ?
> llog_open_create+0x78/0x320
> [obdclass] [1353498.968949] [<ffffffffc12e55f0>] ?
> mdd_root_get+0xf0/0xf0 [mdd] [1353498.968954]
> [<ffffffffc12ec7af>]
> mdd_prepare+0x13ff/0x1c70 [mdd] [1353498.968966]
> [<ffffffffc166b037>]
> mdt_prepare+0x57/0x3b0 [mdt] [1353498.968983]
> [<ffffffffc1183afd>]
> server_start_targets+0x234d/0x2bd0 [obdclass] [1353498.968999]
> [<ffffffffc1153500>] ? class_config_dump_handler+0x7e0/0x7e0
> [obdclass] [1353498.969012] [<ffffffffc118541d>]
> server_fill_super+0x109d/0x185a [obdclass] [1353498.969025]
> [<ffffffffc115cef8>] lustre_fill_super+0x328/0x950 [obdclass]
> [1353498.969038] [<ffffffffc115cbd0>] ?
> lustre_common_put_super+0x270/0x270 [obdclass] [1353498.969041]
> [<ffffffffb561f3bf>] mount_nodev+0x4f/0xb0 [1353498.969053]
> [<ffffffffc1154f18>] lustre_mount+0x38/0x60 [obdclass]
> [1353498.969055] [<ffffffffb561ff3e>] mount_fs+0x3e/0x1b0
> [1353498.969060] [<ffffffffb563d4b7>]
> vfs_kern_mount+0x67/0x110 [1353498.969062]
> [<ffffffffb563fadf>] do_mount+0x1ef/0xce0 [1353498.969066]
> [<ffffffffb55f7c2c>] ? kmem_cache_alloc_trace+0x3c/0x200
> [1353498.969069] [<ffffffffb5640913>] SyS_mount+0x83/0xd0
> [1353498.969074] [<ffffffffb5b20795>]
> system_call_fastpath+0x1c/0x21 [1353498.969079] LustreError:
> 25582:0:(llog_cat.c:1027:llog_cat_reverse_process_cb())
> 36ca26b-MDD0000: fail to destroy empty log: rc = -30
> [1353498.970785] CPU: 6 PID: 25582 Comm: mount.lustre Kdump:
> loaded Tainted: P OE ------------
> 3.10.0-862.6.3.el7.x86_64 #1
> [1353498.970786] Hardware name: Supermicro
> SYS-6027TR-D71FRF/X9DRT,
> BIOS 3.2a 08/04/2015 [1353498.970787] Call Trace:
> [1353498.970790] [<ffffffffb5b0e80e>] dump_stack+0x19/0x1b
> [1353498.970795] [<ffffffffc0cbe5db>]
> osd_trans_create+0x38b/0x3d0
> [osd_zfs] [1353498.970807] [<ffffffffc1117921>]
> llog_cancel_rec+0xc1/0x880 [obdclass] [1353498.970817]
> [<ffffffffc111e13b>] llog_cat_cleanup+0xdb/0x380 [obdclass]
> [1353498.970827] [<ffffffffc111f14d>]
> llog_cat_reverse_process_cb+0x29d/0x3f0 [obdclass]
> [1353498.970838]
> [<ffffffffc111a32c>] llog_reverse_process+0x38c/0xaa0 [obdclass]
> [1353498.970848] [<ffffffffc111eeb0>] ?
> llog_cat_process_cb+0x4e0/0x4e0 [obdclass] [1353498.970858]
> [<ffffffffc111af69>] llog_cat_reverse_process+0x179/0x270
> [obdclass]
> [1353498.970868] [<ffffffffc1115585>] ?
> llog_init_handle+0xd5/0x9a0
> [obdclass] [1353498.970878] [<ffffffffc1116e78>] ?
> llog_open_create+0x78/0x320 [obdclass] [1353498.970883]
> [<ffffffffc12e55f0>] ? mdd_root_get+0xf0/0xf0 [mdd]
> [1353498.970887]
> [<ffffffffc12ec7af>] mdd_prepare+0x13ff/0x1c70 [mdd]
> [1353498.970894]
> [<ffffffffc166b037>] mdt_prepare+0x57/0x3b0 [mdt]
> [1353498.970908]
> [<ffffffffc1183afd>] server_start_targets+0x234d/0x2bd0
> [obdclass]
> [1353498.970924] [<ffffffffc1153500>] ?
> class_config_dump_handler+0x7e0/0x7e0 [obdclass]
> [1353498.970938]
> [<ffffffffc118541d>] server_fill_super+0x109d/0x185a [obdclass]
> [1353498.970950] [<ffffffffc115cef8>]
> lustre_fill_super+0x328/0x950
> [obdclass] [1353498.970962] [<ffffffffc115cbd0>] ?
> lustre_common_put_super+0x270/0x270 [obdclass] [1353498.970964]
> [<ffffffffb561f3bf>] mount_nodev+0x4f/0xb0 [1353498.970976]
> [<ffffffffc1154f18>] lustre_mount+0x38/0x60 [obdclass]
> [1353498.970978] [<ffffffffb561ff3e>] mount_fs+0x3e/0x1b0
> [1353498.970980] [<ffffffffb563d4b7>] vfs_kern_mount+0x67/0x110
> [1353498.970982] [<ffffffffb563fadf>] do_mount+0x1ef/0xce0
> [1353498.970984] [<ffffffffb55f7c2c>] ?
> kmem_cache_alloc_trace+0x3c/0x200 [1353498.970986]
> [<ffffffffb5640913>] SyS_mount+0x83/0xd0 [1353498.970989]
> [<ffffffffb5b20795>] system_call_fastpath+0x1c/0x21
> [1353498.970996]
> LustreError: 25582:0:(mdd_device.c:354:mdd_changelog_llog_init())
> 36ca26b-MDD0000: changelog init failed: rc = -30 [1353498.972790]
> LustreError: 25582:0:(mdd_device.c:427:mdd_changelog_init())
> 36ca26b-MDD0000: changelog setup during init failed: rc = -30
> [1353498.974525] LustreError:
> 25582:0:(mdd_device.c:1061:mdd_prepare()) 36ca26b-MDD0000:
> failed to
> initialize changelog: rc = -30 [1353498.976229] LustreError:
> 25582:0:(obd_mount_server.c:1879:server_fill_super()) Unable
> to start
> targets: -30 [1353499.072002] LustreError:
> 25582:0:(obd_mount.c:1582:lustre_fill_super()) Unable to mount
> (-30)
>
>
> I’m hoping those traces mean something to someone - any ideas?
>
> Thanks!
>
> --
> Benjamin S. Kirk
>
> _______________________________________________
> lustre-discuss mailing list
> lustre-discuss at lists.lustre.org
> <mailto:lustre-discuss at lists.lustre.org>
> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
>
>
> Cheers, Andreas
> ---
> Andreas Dilger
> CTO Whamcloud
>
>
>
>
>
>
>
> _______________________________________________
> lustre-discuss mailing list
> lustre-discuss at lists.lustre.org
> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
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