Applicable to:
- Plesk for Linux
Symptoms
-
Plesk login is slow or impossible: a white page is shown instead.
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Plesk interface and websites are working slow. For example, opening the menus Domains > example.com > File Manager or Plesk > Subscriptions takes significant time.
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Restoration of a Plesk-made backup (specifically, the execution of the utility
/usr/lib64/plesk-9.0/sw-tar) can take a lot of time. -
With the Plesk debug mode enabled, the commands logged to the log file
/var/log/plesk/panel.logshow that IO operations take a long time to complete:Example of a slow server:
CONFIG_TEXT: DEBUG [util_exec] [8053637617e48c1bb69e7a15225a3d18-0] Starting: filemng root file_exists /root/.autoinstaller/microupdates.xml --allow-root, stdin:
DEBUG [util_exec] [8053637617e48c1bb69e7a15225a3d18-0] Finished in 8.4113s, Error code: 0, stdout: 0
, stderr:
DEBUG [util_exec] [5b2bb52605a53] Starting: filemng root cat /root/.autoinstaller/microupdates.xml --allow-root, stdin:
DEBUG [util_exec] [5b2bb52605a53] Finished in 16.7445s, Error code: TRUE, stdout: , stderr:Example of normal environment:
CONFIG_TEXT: DEBUG [util_exec] [a05daf3428f1f60f55e3b94e5bfc4cb6-0] Starting: filemng root file_exists /root/.autoinstaller/microupdates.xml --allow-root, stdin:
[2018-06-21 21:23:54.472] DEBUG [util_exec] [a05daf3428f1f60f55e3b94e5bfc4cb6-0] Finished in 0.01272s, Error code: 0, stdout: 0
, stderr:
DEBUG [util_exec] [5b2bb4fa73614] Starting: filemng root cat /root/.autoinstaller/microupdates.xml --allow-root, stdin:
[2018-06-21 21:23:54.486] DEBUG [util_exec] [5b2bb4fa73614] Finished in 0.01314s, Error code: TRUE, stdout: , stderr: -
Disk write speed is very low:
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Streaming I/O
Example of a slow server:
# dd if=/dev/zero of=/root/testfile bs=512 count=5000 oflag=direct
3563+0 records in
3563+0 records out
1824256 bytes (1.8 MB) copied, 673.815 s, 2.7 kB/sExample of normal environment:
# dd if=/dev/zero of=/root/testfile bs=512 count=5000 oflag=direct
5000+0 records in
5000+0 records out
2560000 bytes (2.6 MB) copied, 0.0180294 s, 142 MB/s -
Latency
Example of a slow server:
# dd if=/dev/zero of=/root/testfile bs=1024M count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 52.631 s, 20.4 MB/sExample of normal environment:
# dd if=/dev/zero of=/root/testfile bs=1024M count=1 oflag=direct
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB) copied, 1.75607 s, 611 MB/s<
-
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When running the utility
top, high %wa percentage is displayed (CPU waiting for the IO resources):# top - 10:52:54 up 3:41, 7 users, load average: 105.98, 102.68, 107.96
Tasks: 466 total, 19 running, 446 sleeping, 1 stopped, 0 zombie
%Cpu(s): 8.5 us, 8.5 sy, 0.0 ni, 0.1 id, 82.8 wa, 0.0 hi, 0.1 si, 0.0 st -
When running the utility
iotop, multiple processes are running with 99.99% IO:
Cause
The hard disk performance is unable to maintain the IO load.
Resolution
-
Check the processes are run on the server and stop unneeded processes.
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Contact the service provider to troubleshoot the IO performance and modify the disk subsystem to provide better IO.
Note: Amazon AWS and Lightsail instances may throttle the IO performance: I/O Credits and Burst Performance
Comments
4 comments
Before you start checking all of the above I suggest you check the /etc/resolv.conf file.
If localhost (127.0.0.1) is not in the first place then change that.
If you are already using dynamic addition to resolv.conf, the default option on server providers, then make sure that the first place is 127.0.0.1. You can achieve this by editing the files in /etc/resolvconf/resolv.conf.d/ in the head file add entries:
nameserver ::1
nameserver 127.0.0.1
I have spent a lot of time to come to the conclusion that if you have a foreign server entered and it is slow or with restrictions, the whole plesk panel works slowly and even can fail to work.
I checked that, but resolv.conf will be overwritten by /etc/systemd/resolved.conf
Tried to use it there but no success.
Any other ideas? IO is not the issue here.
Read again. I diden't write change /etc/resolv.conf, i write go to directory /etc/resolvconf/resolv.conf.d/ find file "head" and add entries.
This is the configuration directory in Debian. In other distributions, I don't know.
Another problem could be a lack of cache memory in the RAID controller, especially RAID 5, or a buffer that is not turned on due to the lack of a memory backup battery. It depends on the solution in the controller.
Yes I know and the equivalent to /etc/resolvconf/resolv.conf.d/head is /etc/systemd/resolved.conf on ubuntu.
Thanks for the tip with the raid controller, I'll check that.
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