Plesk for Linux
kb: technical
ext: migrator
ABT: Group B
Applicable to:
- Plesk for Linux
Symptoms
- High CPU wait, I/O and Load Average, while the backup is generated in Plesk or outbound migration is performed.
- Sites may show 504 Gateway Timeout error.
Cause
/usr/bin/pigz and/or /bin/tar consumes high CPU resource during the backup process as it is involved in the backup compress process. This applies to Plesk versions lower than 18.0.40 because starting from 18.0.40 Plesk uses ZSTD compression.
Resolution
There are three possible solutions to reduce the server load during backup process at Tools & Settings > Backup Manager > Settings:
- Run scheduled backup processes with low priority
-
Run all backup processes with low priority. Since Plesk Obsidian 18.0.40 it is possible to set the compression level and IO priority:
-
Do not compress backup files (this way the backup size will be larger, but load average will be less as
pigzprocess that is involved in the backup compress process will be skipped).
These options launch pigz and tar with nice.
Note: these options increase the backup time. Other server tasks will not be affected. If there is a highly-loaded domain on a server that takes a lot of server resources, re-schedule the time to start a backup to the night when the number of visitors to the site is less.
Comments
Hi,
Not work for me, i have set low priority on all options but still with very high I/O usage
My bests
Hi, Could you please open a support ticket with us? We would like to invesigate what is going on: https://support.plesk.com/hc/en-us/articles/12388090147095-How-to-get-support-directly-from-Plesk
This issue persists since years. Even on a 6-core virtual machine with 24 GB of RAM and reduced priority, backups sometimes slow down the whole server.
B Pfl Hi,
This applies to Plesk versions lower than 18.0.40 because starting from 18.0.40 Plesk uses ZSTD compression. Please make sure you are running the latest version or update in Tools & Settings > Updates.
If you are running the latest version please open a support ticket with us to investigate the issue https://support.plesk.com/hc/en-us/articles/12388090147095-How-to-get-support-directly-from-Plesk
Julian Bonpland Mignaquy we use Plesk 18.0.71 Update 2.
Julian Bonpland Mignaquy what is interesting to observe: If you have a look at the CPU and memory usage on the Plesk start page during a backup, the percentages do not add up to 100% any more:
B Pfl could you please specify which percentages do not add up?
Julian Bonpland Mignaquy If I read the diagram correctly, the purple or yellow area stands for unused CPU / memory. How can it be that this changes if no change to available CPUs and memory happen. (btw: the diagram for memory might be better if the full memory capacity of 24 GB would be shown).
B Pfl hi! please open a support ticket with us https://support.plesk.com/hc/en-us/articles/12377663472791-How-to-submit-a-request-to-Plesk-support?_gl=1*mctp6s*_gcl_au*MTkxNDI0MTIxMS4xNzU0MjI0MDQ4*_ga*MTE3NzQ0NTg2MC4xNzUxNjE1NzI0*_ga_5SX3L7KZCY*czE3NTkxMzAwMzIkbzE3OCRnMSR0MTc1OTEzMDA4MyRqOSRsMCRoMTY3ODUwMDQ5Mw.. so we can investigate it.
Please allow configuration of the CPU affinity for the pstd processes, so at least it will be possible to limit high CPU usage for some cores and let hosting related processes to run on other processes.
It will certainly allow better control over server's CPU usage during backup than just using process priority control.
Here is a relevant answer for the CPU affinity on SO.
Romans Sidorovs Hi, the feature that you have reported is yet to be implemented in Plesk. I would like to ask you to take a part in product improvement and share your thoughts with development team by the link https://features.plesk.com/tabs/28-planned-roadmap
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