# Socket file in multi instance mysql@

**URL:** <https://forums.percona.com/t/socket-file-in-multi-instance-mysql/10606>\
**Category:** Percona Server for MySQL 8.0\
**Tags:** mysql\
**Created:** [May 27, 2021, 5:10am UTC](https://forums.percona.com/t/socket-file-in-multi-instance-mysql/10606 "2021-05-27T05:10:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Figueroa](https://avatars.discourse-cdn.com/v4/letter/f/ce73a5/32.png) [@Figueroa](https://forums.percona.com/u/Figueroa)\
**Post date:** [May 27, 2021, 5:10am UTC](https://forums.percona.com/t/socket-file-in-multi-instance-mysql/10606/1 "2021-05-27T05:10:03Z")

</div>

I find strange bug or error but I not sure if systemD or mysql.

I have two instance in same server db00, If I stop or restart any instance, it delete the pid and socket file of the other service but the other service is still working.

```
Server version: 8.0.23-14 Percona Server
[mysqld@db01]
pid-file = /var/run/mysqld/mysql_db01.pid
socket = /var/run/mysqld/mysql_db01.sock
datadir = /var/lib/mysql_db01
log-error = /var/log/mysql_db01/error.log
port = 3306
server_id = 101
mysqlx = 0
...
[mysqld@db02]
pid-file = /var/run/mysqld/mysql_db02.pid
socket = /var/run/mysqld/mysql_db02.sock
datadir = /var/lib/mysql_db02
log-error = /var/log/mysql_db02/error.log
port = 3307
server_id = 202
mysqlx = 0
...

```

for example:

> both services are running , and the files exist in **/var/run/mysqld/**

```
#ls -l /var/run/mysqld/:
drwxr-xr-x 2 root root 40 May 27 01:15 ./
drwxr-xr-x 35 root root 1080 May 27 01:15 ../
-rw-r----- 1 mysql mysql 7 May 27 01:07 mysql_db01.pid
srwxrwxrwx 1 mysql mysql 0 May 27 01:07 mysql_db01.sock=
-rw------- 1 mysql mysql 7 May 27 01:07 mysql_db01.sock.lock
-rw-r----- 1 mysql mysql 7 May 27 01:08 mysql_db02.pid
srwxrwxrwx 1 mysql mysql 0 May 27 01:08 mysql_db02.sock=
-rw------- 1 mysql mysql 7 May 27 01:08 mysql_db02.sock.lock
#

```

> stop the service ,mysql@db02 and delete all files in **/var/run/mysql**

```
#systemctl stop mysql@db02
#ll /var/run/mysqld/:
drwxr-xr-x 2 root root 40 May 27 01:15 ./
drwxr-xr-x 35 root root 1080 May 27 01:15 ../
#

```

> For restore the files we need stop (or restart) the other instance

```
#systemctl stop mysql@db01
#ll /var/run/mysqld/:
drwxr-xr-x 2 root root 40 May 27 01:15 ./
drwxr-xr-x 35 root root 1080 May 27 01:15 ../
#

```

> And start one by one.

```
#systemctl start mysql@db01
#ll /var/run/mysqld/
drwxr-xr-x 2 root root 40 May 27 01:15 ./
drwxr-xr-x 35 root root 1080 May 27 01:15 ../
-rw-r----- 1 mysql mysql 7 May 27 01:18 mysql_db01.pid
srwxrwxrwx 1 mysql mysql 0 May 27 01:18 mysql_db01.sock
-rw------- 1 mysql mysql 7 May 27 01:18 mysql_db01.sock.lock
#
#systemctl start mysql@db02
#ll /var/run/mysqld/
drwxr-xr-x 2 root root 40 May 27 01:15 ./
drwxr-xr-x 35 root root 1080 May 27 01:15 ../
-rw-r----- 1 mysql mysql 7 May 27 01:18 mysql_db01.pid
srwxrwxrwx 1 mysql mysql 0 May 27 01:18 mysql_db01.sock
-rw------- 1 mysql mysql 7 May 27 01:18 mysql_db01.sock.lock
-rw-r----- 1 mysql mysql 7 May 27 01:19 mysql_db02.pid
srwxrwxrwx 1 mysql mysql 0 May 27 01:19 mysql_db02.sock
-rw------- 1 mysql mysql 7 May 27 01:19 mysql_db02.sock.lock

```

I don’t think it is good idea create other dir in /var/run (in case of reboot), any idea? maybe is service or config mysql

---

<div class="post-metadata">

**Author:** ![Evgeniy\_Patlan](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/evgeniy_patlan/32/41_2.png) [@Evgeniy\_Patlan](https://forums.percona.com/u/Evgeniy_Patlan)\
**Post date:** [July 6, 2021, 4:23pm UTC](https://forums.percona.com/t/socket-file-in-multi-instance-mysql/10606/2 "2021-07-06T16:23:04Z")

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Hi. Could you please show the part of log to understand the systemd behavior.