[dm-devel] multipath-tools: prevent unnecessary reinstate，

Thu Mar 3 08:19:26 UTC 2016

Thanks a lots , the problem has been solved , the multipath-tool deb building leads to the dm-mpath.rules lost.

________________________________
zhangguanghui

发件人： zhangguanghui 10102 (CCPL)<mailto:zhang.guanghui at h3c.com>
发送时间： 2016-03-03 09:51
收件人： Nalla, Ravikanth<mailto:ravikanth.nalla at hpe.com>; dm-devel-bounces at redhat.com<mailto:dm-devel-bounces at redhat.com>; dm-devel at redhat.com<mailto:dm-devel at redhat.com>
主题： Re: RE: multipath-tools: prevent unnecessary reinstate，
Thanks a lots , The chekerloop thread of multipathd daemon will be monitoring all the paths periodically via check_path.
As far as I know,  each tur cmd takes a 5s interval in default,  a previously failed path may be automatically reinstated.
According to the log, it looks to be a endless loop(reinstate_path and fail_path frequently switch in 1 second),
only in the case of  prio alua and two path groups.  when the case of prio const and one path group is normal.
so I don't know what is that.

________________________________
zhangguanghui

发件人： Nalla, Ravikanth<mailto:ravikanth.nalla at hpe.com>
发送时间： 2016-03-02 21:05
收件人： zhangguanghui 10102 (CCPL)<mailto:zhang.guanghui at h3c.com>; dm-devel-bounces at redhat.com<mailto:dm-devel-bounces at redhat.com>; dm-devel at redhat.com<mailto:dm-devel at redhat.com>
主题： RE: multipath-tools: prevent unnecessary reinstate，
1. When all paths fail, reinstate_path and fail_path frequently switch, so a previously failed path is automatically reinstated,
    Could someone tell me why is that?  moreover,  dm_reinstate_path not being called in multipathd.
dm_reinstate_path is indeed initiated by multipathd when path current status from the cheker module is found to be PATH_UP / PATH_GHOST(online but path unusable) which is not same as previous status.

The chekerloop thread of multipathd daemon will be monitoring all the paths periodically via check_path, where it initiates fail_path, re-instate  etc.,
messages to device mapper based on the current paths status (PATH_DOWN/ PATH_UP/PATH_GHOST/ PATH_SHAKY etc.,).

-          As a first step, check_path initiates path_offline  to check path status to see if it is offline/online from sysfs.  If the path is offline(PATH_DOWN) or PATH_SHAKY and different from previous status it initiates fail_path msg to device mapper. If path is online (PATHUP) it initiates respective checker (in this case tur) to ping and check the new status of the path.

o   If check_path founds from the tur checker module that the new path status is PATH_UP (tur cmd succeeds) and PATH_GHOST (LOGICAL UNIT NOT ACCESSIBLE , TARGET PORT IN STANDBY STATE) and not same as previous status  then it initiate reinstate_path msg to device mapper.

o   If check_path founds from the tur checker module that the new path status is PATH_DOWN (tur cmd fails) or PATH_SHAKY(not used in tur checker anyway) and not same as previous status then it initiate fail_path msg to device mapper.

In the below situation it looks to be the case where the paths are not-stable/flakey resulting in reinstate_path/ fail_path by the multipathd at each tur cmd failure or success.

Mar 2 16:06:50 cvknode129 kernel: [68389.817587] sd 3:0:0:0: rejecting I/O to offline device
Mar 2 16:06:50 cvknode129 kernel: [68389.817598] device-mapper: multipath: Failing path 8:16. 3483
Mar 2 16:06:50 cvknode129 kernel: [68389.817601] CPU: 0 PID: 3 Comm: ksoftirqd/0 Tainted: G OE 4.1.0-generic #2
Mar 2 16:06:50 cvknode129 kernel: [68389.817602] Hardware name: HP ProLiant BL460c Gen8, BIOS I31 02/25/2012
Mar 2 16:06:50 cvknode129 kernel: [68389.817603] ffff880816673500 ffff88081be8bd08 ffffffff817e8924 0000000000000007
Mar 2 16:06:50 cvknode129 kernel: [68389.817605] ffff880816673528 ffff88081be8bd38 ffffffffc019c75e 00000000fffffffb
Mar 2 16:06:50 cvknode129 kernel: [68389.817607] ffff88003698b458 ffff880816673500 0000000000000010 ffff88081be8bd88
Mar 2 16:06:50 cvknode129 kernel: [68389.817609] Call Trace:
Mar 2 16:06:50 cvknode129 kernel: [68389.817612] [<ffffffff817e8924>] dump_stack+0x45/0x57
Mar 2 16:06:50 cvknode129 kernel: [68389.817622] [<ffffffffc019c75e>] fail_path+0x7e/0xf0 [dm_multipath]
Mar 2 16:06:50 cvknode129 kernel: [68389.817624] [<ffffffffc019d60e>] multipath_end_io+0x5e/0x190 [dm_multipath]
Mar 2 16:06:50 cvknode129 kernel: [68389.817627] [<ffffffff81020e19>] ? sched_clock+0x9/0x10
Mar 2 16:06:50 cvknode129 kernel: [68389.817629] [<ffffffff81666cf3>] dm_softirq_done+0xd3/0x250
Mar 2 16:06:50 cvknode129 kernel: [68389.817642] [<ffffffff81015686>] ? __switch_to+0x1e6/0x580
Mar 2 16:06:50 cvknode129 kernel: [68389.817645] [<ffffffff81397d9b>] blk_done_softirq+0x7b/0x90
Mar 2 16:06:50 cvknode129 kernel: [68389.817647] [<ffffffff810820fe>] __do_softirq+0xde/0x2d0
Mar 2 16:06:50 cvknode129 kernel: [68389.817649] [<ffffffff81082310>] run_ksoftirqd+0x20/0x60
Mar 2 16:06:50 cvknode129 kernel: [68389.817650] [<ffffffff810a0fd6>] smpboot_thread_fn+0x116/0x170
Mar 2 16:06:50 cvknode129 kernel: [68389.817652] [<ffffffff810a0ec0>] ? sort_range+0x30/0x30
Mar 2 16:06:50 cvknode129 kernel: [68389.817653] [<ffffffff8109db59>] kthread+0xc9/0xe0
Mar 2 16:06:50 cvknode129 kernel: [68389.817655] [<ffffffff8109da90>] ? flush_kthread_worker+0x90/0x90
Mar 2 16:06:50 cvknode129 kernel: [68389.817657] [<ffffffff817f0ca2>] ret_from_fork+0x42/0x70
Mar 2 16:06:50 cvknode129 kernel: [68389.817658] [<ffffffff8109da90>] ? flush_kthread_worker+0x90/0x90
Mar 2 16:06:50 cvknode129 kernel: [68389.843090] CPU: 3 PID: 43112 Comm: multipath Tainted: G OE 4.1.0-generic #2
Mar 2 16:06:50 cvknode129 kernel: [68389.843092] Hardware name: HP ProLiant BL460c Gen8, BIOS I31 02/25/2012
Mar 2 16:06:50 cvknode129 kernel: [68389.843093] ffff880816673528 ffff8807efcdfb78 ffffffff817e8924 ffff88081952e580
Mar 2 16:06:50 cvknode129 kernel: [68389.843095] 0000000000000000 ffff8807efcdfbc8 ffffffffc019e20e 0000000000000000
Mar 2 16:06:50 cvknode129 kernel: [68389.843097] ffff880036a81440 0000000000000008 ffff88081a288e78 ffffc90006d49040
Mar 2 16:06:50 cvknode129 kernel: [68389.843098] Call Trace:
Mar 2 16:06:50 cvknode129 kernel: [68389.843101] [<ffffffff817e8924>] dump_stack+0x45/0x57
Mar 2 16:06:50 cvknode129 kernel: [68389.843106] [<ffffffffc019e20e>] reinstate_path+0xae/0x1a0 [dm_multipath]
Mar 2 16:06:50 cvknode129 kernel: [68389.843108] [<ffffffffc019e160>] ? multipath_map+0x20/0x20 [dm_multipath]
Mar 2 16:06:50 cvknode129 kernel: [68389.843113] [<ffffffffc019d9ce>] multipath_message+0x18e/0x360 [dm_multipath]
Mar 2 16:06:50 cvknode129 kernel: [68389.843115] [<ffffffff8166dbc5>] target_message+0x255/0x340
Mar 2 16:06:50 cvknode129 kernel: [68389.843116] [<ffffffff8166d970>] ? __dev_status+0x150/0x150
Mar 2 16:06:50 cvknode129 kernel: [68389.843118] [<ffffffff8166ef7a>] ctl_ioctl+0x24a/0x520
Mar 2 16:06:50 cvknode129 kernel: [68389.843120] [<ffffffff8166f263>] dm_ctl_ioctl+0x13/0x20
Mar 2 16:06:50 cvknode129 kernel: [68389.843122] [<ffffffff812142d6>] do_vfs_ioctl+0x86/0x530
Mar 2 16:06:50 cvknode129 kernel: [68389.843124] [<ffffffff8106a10f>] ? __do_page_fault+0x1af/0x470
Mar 2 16:06:50 cvknode129 kernel: [68389.843126] [<ffffffff81214811>] SyS_ioctl+0x91/0xb0
Mar 2 16:06:50 cvknode129 kernel: [68389.843128] [<ffffffff817f0872>] system_call_fastpath+0x16/0x75
Mar 2 16:06:50 cvknode129 kernel: [68389.843255] sd 5:0:0:0: rejecting I/O to offline device
Mar 2 16:06:50 cvknode129 kernel: [68389.843266] device-mapper: multipath: Failing path 8:48. 3514

device {
vendor "MacroSAN"
product "LU"
path_grouping_policy "group_by_prio"
path_checker "tur"
features "1 queue_if_no_path"
hardware_handler "0"
prio "alua"
failback 15
rr_weight "priorities"
no_path_retry 30
rr_min_io 1000
}

3600b34223c09334d0467dfcd5d0000da dm-0 MacroSAN,LU
size=50G features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=50 status=active
| `- 5:0:0:0 sdd 8:48 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
`- 3:0:0:0 sdb 8:16 active ready running

Thanks!

Best regards!

________________________________
zhangguanghui
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