Symptoms
Virtuozzo storage CS service cannot start, e.g.
CS init failed [892044] /dev/sdh1 Server /pstorage/cs-cs5/data
In CS log /pstorage/cs-cs5/data/logs/cs.log.gz
01-06-18 22:21:09.080 CS started
01-06-18 22:21:09.081 dump_mds_list: Load MDS list from bootstrap
01-06-18 22:21:09.081 mds_select: No bootstrap MDS found
01-06-18 22:21:09.081 register_work: MDS is not resolved, delaying
01-06-18 22:21:09.084 res_search() failed: Unknown host
01-06-18 22:21:09.084 Trying to find out the zone name by other means...
01-06-18 22:21:09.087 Failed to get host canonical name: Name or service not known
01-06-18 22:21:09.112 mdns: error joining group 224.0.0.251, interface 35: No buffer space available
01-06-18 22:21:09.112 mdns: error joining group 224.0.0.251, interface 36: No buffer space available
Cause
There is a configurable limit of system-wide multicast memberships(how many multicast IP addresses the node can listen to). On a node with a lot of interfaces, this limit should be increased, as each interface adds a listening socket.
Resolution
1. Increase the limit
echo 50 > /proc/sys/net/ipv4/igmp_max_memberships
2. Restart the service
In Virtuozzo 6:
service pstorage-csd restart </PATH/TO/CS_REPOSITORY>
In Virtuozzo Hybrid Server 7:
systemctl restart vstorage-csd.vhs-<clustername>.<CS_ID>.service
3. To make the change permanent, modify net.ipv4.igmp_max_memberships in /etc/sysctl.conf.