Zabbix server is not running: the information displayed may not be current

[digihe.mum]

Need help. getting error--> Zabbix server is not running: the information displayed may not be current on Cent OS 7

[Atsushi]

If the Zabbix server process is running, try disabling SELinux or setting a policy.

[digihe.mum]

SELinux is already disabled

[Atsushi]

Use the ps command to check whether the zabbix_server process has started. If not, check the Zabbix server logs.

[mfortes]

First, check your log and post here...
tail -f /var/log/zabbix/zabbix-server.log

[digihe.mum]

[root@localhost /]# tail -f /var/log/zabbix/zabbix_server.log
zabbix_server [11847]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11864]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11869]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11880]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11884]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11888]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11913]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11935]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11939]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11943]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11952]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11956]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11968]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11972]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11976]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11980]: cannot open log: cannot create semaphore set: [28] No space left on device
zabbix_server [11984]: cannot open log: cannot create semaphore set: [28] No space left on device

[Atsushi]

Check for unnecessary semaphores using the ipcs command and delete them using the ipcrm command, or restart the OS.
For example, after stopping all Zabbix-related services, execute the ipcs command as the root user. After deleting all the owners who are displayed as zabbix users with the ipcrm command, start Zabbix related services.

If you don't know the ipcs command, restarting the OS is an easy way.

[digihe.mum]

4700:20200317:163118.087 IPv6 support: YES
4700:20200317:163118.087 TLS support: YES
4700:20200317:163118.087 ******************************
4700:20200317:163118.087 using configuration file: /etc/zabbix/zabbix_server.conf
4700:20200317:163118.093 current database version (mandatory/optional): 03040000/03040007
4700:20200317:163118.093 required mandatory version: 03040000
4700:20200317:163118.373 __mem_malloc: skipped 0 asked 48 skip_min 4294967295 skip_max 0
4700:20200317:163118.373 [file:strpool.c,line:51] zbx_mem_malloc(): out of memory (requested 47 bytes)
4700:20200317:163118.373 [file:strpool.c,line:51] zbx_mem_malloc(): please increase CacheSize configuration parameter
4700:20200317:163118.373 === memory statistics for string pool ===
4700:20200317:163118.373 free chunks of size 24 bytes: 1
4700:20200317:163118.373 min chunk size: 24 bytes
4700:20200317:163118.373 max chunk size: 24 bytes
4700:20200317:163118.373 memory of total size 1257920 bytes fragmented into 13760 chunks
4700:20200317:163118.373 of those, 24 bytes are in 1 free chunks
4700:20200317:163118.373 of those, 1037752 bytes are in 13759 used chunks
4700:20200317:163118.373 ================================
4700:20200317:163118.373 === Backtrace: ===
4700:20200317:163118.374 12: /usr/sbin/zabbix_server(zbx_backtrace+0x35) [0x557205dd0889]
4700:20200317:163118.374 11: /usr/sbin/zabbix_server(__zbx_mem_malloc+0x163) [0x557205dcc7a8]
4700:20200317:163118.374 10: /usr/sbin/zabbix_server(+0xe5eec) [0x557205dcceec]
4700:20200317:163118.374 9: /usr/sbin/zabbix_server(zbx_hashset_insert_ext+0x2d4) [0x557205dd5a46]
4700:20200317:163118.374 8: /usr/sbin/zabbix_server(zbx_strpool_intern+0x5d) [0x557205dcd0ab]
4700:20200317:163118.374 7: /usr/sbin/zabbix_server(+0xba9bb) [0x557205da19bb]
4700:20200317:163118.374 6: /usr/sbin/zabbix_server(+0xbeefa) [0x557205da5efa]
4700:20200317:163118.374 5: /usr/sbin/zabbix_server(DCsync_configuration+0x77c) [0x557205daafbf]
4700:20200317:163118.374 4: /usr/sbin/zabbix_server(MAIN_ZABBIX_ENTRY+0x5e8) [0x557205d27575]
4700:20200317:163118.374 3: /usr/sbin/zabbix_server(daemon_start+0x325) [0x557205dd00d6]
4700:20200317:163118.374 2: /usr/sbin/zabbix_server(main+0x312) [0x557205d26f8b]
4700:20200317:163118.374 1: /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f9a87fa5505]
4700:20200317:163118.375 0: /usr/sbin/zabbix_server(+0x346a9) [0x557205d1b6a9]

[digihe.mum]

resolved after increasing CacheSize to 32M

Please suggest what should be ideal CacheSize to be configured for 30 Hosts

[Atsushi]

It cannot be inferred from the number of 30 hosts. It depends on the number of items and how they are monitored.
The current cache usage can be viewed by linking the template "Template App Zabbix Server" to Zabbix server. Please check the graph "Zabbix cache usage,% free" etc.