[ClusterLabs] Antw: Re: [Cluster-devel] DLM connection channel switch take too long time (> 5mins)

[Ulrich Windl]

Hi!

What surprises me most is that a connect(...O_NONBLOCK) actually blocks:

EINPROGRESS
              The  socket  is  non-blocking  and the connection cannot be com-
              pleted immediately.

Regards,
Ulrich


>>> "Gang He" <ghe at suse.com> schrieb am 08.03.2018 um 10:48 in Nachricht
<5AA17765020000F9000ADCF2 at prv-mh.provo.novell.com>:
> Hi Feldhost,
> 
> I use active rrp_mode in corosync.conf and reboot the cluster to let the 
> configuration effective.
> But, the about 5 mins hang in new_lockspace() function is still here.
> 
> Thanks
> Gang
>  
> 
>>>> 
>> Hi, so try to use active mode.
>> 
>> https://www.suse.com/documentation/sle_ha/book_sleha/data/sec_ha_installatio 
> 
>> n_terms.html
>> 
>> That fixes I saw in 4.14.*
>> 
>>> On 8 Mar 2018, at 09:12, Gang He <ghe at suse.com> wrote:
>>> 
>>> Hi Feldhost,
>>> 
>>> 
>>>>>> 
>>>> Hello Gang He,
>>>> 
>>>> which type of corosync rrp_mode you use? Passive or Active? 
>>> clvm1:/etc/corosync # cat corosync.conf  | grep rrp_mode
>>>        rrp_mode:       passive
>>> 
>>> Did you try test both?
>>> No, only this mode. 
>>> Also, what kernel version you use? I see some SCTP fixes in latest kernels.
>>> clvm1:/etc/corosync # uname -r
>>> 4.4.114-94.11-default
>>> It looks that sock->ops->connect() function is blocked for too long time before 
>> return, under broken network situation. 
>>> In normal network, sock->ops->connect() function returns very quickly.
>>> 
>>> Thanks
>>> Gang
>>> 
>>>> 
>>>>> On 8 Mar 2018, at 08:52, Gang He <ghe at suse.com> wrote:
>>>>> 
>>>>> Hello list and David Teigland,
>>>>> 
>>>>> I got a problem under a two rings cluster, the problem can be reproduced 
>>>> with the below steps.
>>>>> 1) setup a two rings cluster with two nodes.
>>>>> e.g. 
>>>>> clvm1(nodeid 172204569)  addr_list eth0 10.67.162.25 eth1 192.168.152.240
>>>>> clvm2(nodeid 172204570)  addr_list eth0 10.67.162.26 eth1 192.168.152.103
>>>>> 
>>>>> 2) the whole cluster works well, then I put eth0 down on node clvm2, and 
>>>> restart pacemaker service on that node.
>>>>> ifconfig eth0 down
>>>>> rcpacemaker restart
>>>>> 
>>>>> 3) the whole cluster still work well (that means corosync is very smooth to 
>>>> switch to the other ring).
>>>>> Then, I can mount ocfs2 file system on node clvm2 quickly with the command 
>>>>> mount /dev/sda /mnt/ocfs2 
>>>>> 
>>>>> 4) Next, I do the same mount on node clvm1, the mount command will be hanged 
> 
>> 
>>>> for about 5 mins, and finally the mount command is done.
>>>>> But, if we setup a ocfs2 file system resource in pacemaker,
>>>>> the pacemaker resource agent will consider ocfs2 file system resource 
>>>> startup failure before this command returns,
>>>>> the pacemaker will fence node clvm1. 
>>>>> This problem is impacting our customer's estimate, since they think the two 
>>>> rings can be switched smoothly.
>>>>> 
>>>>> According to this problem, I can see the mount command is hanged with the 
>>>> below back trace,
>>>>> clvm1:/ # cat /proc/6688/stack
>>>>> [<ffffffffa04b8f2d>] new_lockspace+0x92d/0xa70 [dlm]
>>>>> [<ffffffffa04b92d9>] dlm_new_lockspace+0x69/0x160 [dlm]
>>>>> [<ffffffffa04db758>] user_cluster_connect+0xc8/0x350 [ocfs2_stack_user]
>>>>> [<ffffffffa0483872>] ocfs2_cluster_connect+0x192/0x240 [ocfs2_stackglue]
>>>>> [<ffffffffa0577efc>] ocfs2_dlm_init+0x31c/0x570 [ocfs2]
>>>>> [<ffffffffa05c2983>] ocfs2_fill_super+0xb33/0x1200 [ocfs2]
>>>>> [<ffffffff8120e130>] mount_bdev+0x1a0/0x1e0
>>>>> [<ffffffff8120ea1a>] mount_fs+0x3a/0x170
>>>>> [<ffffffff81228bf2>] vfs_kern_mount+0x62/0x110
>>>>> [<ffffffff8122b123>] do_mount+0x213/0xcd0
>>>>> [<ffffffff8122bed5>] SyS_mount+0x85/0xd0
>>>>> [<ffffffff81614b0a>] entry_SYSCALL_64_fastpath+0x1e/0xb6
>>>>> [<ffffffffffffffff>] 0xffffffffffffffff
>>>>> 
>>>>> The root cause is in sctp_connect_to_sock() function in lowcomms.c,
>>>>> 1075
>>>>> 1076         log_print("connecting to %d", con->nodeid);
>>>>> 1077
>>>>> 1078         /* Turn off Nagle's algorithm */
>>>>> 1079         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
>>>>> 1080                           sizeof(one));
>>>>> 1081
>>>>> 1082         result = sock->ops->connect(sock, (struct sockaddr *)&daddr, 
>>>> addr_len,
>>>>> 1083                                    O_NONBLOCK);  <<= here, this invoking 
>>>> will cost > 5 mins before return ETIMEDOUT(-110).
>>>>> 1084         printk(KERN_ERR "sctp_connect_to_sock connect: %d\n", result);
>>>>> 1085
>>>>> 1086         if (result == -EINPROGRESS)
>>>>> 1087                 result = 0;
>>>>> 1088         if (result == 0)
>>>>> 1089                 goto out;
>>>>> 
>>>>> Then, I want to know if this problem was found/fixed before? 
>>>>> it looks DLM can not switch the second ring very quickly, this will impact 
>>>> the above application (e.g. CLVM, ocfs2) to create a new lock space before 
>>>> it's startup.
>>>>> 
>>>>> Thanks
>>>>> Gang
>>>>> 
>>>>> 
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