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Chris99391
Asked: 2018-12-26 09:28:25 +0800 CST

CPU IOWAIT CRITICAL

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I have an error that annoys me enormously because it makes me crash my website at times because the IOWAIT is too high. Here is the mistake I have:

CRITICAL on CPU_IOWAIT (Min:11.3 Mean:14.1 Max:15.7): bioset, bioset, acpi_thermal_pm

when the value is too high I have an ERR_TIMEOUT that appears on my site. Is it possible to fix the problem without changing the machine? Knowing that I have a dedicated server with only 1 website above but with 5 multiboutiques (Prestashop) Thank you for your help.

iowait

2 Answers

  1. This means all your RAM is being used and Linux is using your disk for virtual memory, which is slow and causes iowait because it's waiting on your disk. Prestashop, PHP and MySQL can be configured in many ways that affect performance.

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  2. Look for mysql change logging being disk write hotspots. Often, CMSes (Prestashop, Joomla, WP) track activities through the database, and mysql keeps log of those changes in order to be able to recover from an outage. That means a lot of writing directly to disk.

    If you cannot change the CMS behavior, have a look at innodb_log_file_size (https://forums.mysql.com/read.php?22,32004,32014#msg-32014 and https://www.percona.com/blog/2006/07/03/choosing-proper-innodb_log_file_size/).

    /Per

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