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

[FeldHost™ Admin]

Hi, so try to use active mode.

https://www.suse.com/documentation/sle_ha/book_sleha/data/sec_ha_installation_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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