Explore information related to cache


SolusVM: Cannot Allocate Memory Error – Best fix ?


This article covers the best way to tackle SolusVM: Cannot Allocate Memory Error. In fact, this error happens while booting KVM VPS in SolusVM. This error signifies that there is not enough free memory on the node.

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AWS ElastiCache error - Fix it Now ?


This article covers methods to fix ElastiCache error. Basically, the sort of error messages are returned by Amazon ElastiCache. You may receive other error messages that are returned by ElastiCache, other AWS services, or by Redis.

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Enable Memcached Support In Nagios - How to do it ?


This article covers how to enable Memcached for our customers. You can setup one or more memcached servers (hosts) for use by Nagios XI.

Each memcached host must have its firewall configured to allow traffic on TCP port 11211 to allow Nagios

XI to contact the memcached server. 


To create the firewall rules, run the commands:

$ ufw allow proto tcp from any to any port 11211
$ ufw reload

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PrestaShop back office error 500 or blank page - Fix it Now ?


This article covers methods to resolve PrestaShop back office error 500.

The error happens when the Back-office is accessed only from Debug mode activated or in production mode activated. The characteristic of this error is that it only occurs in one of the modes and not in both.

Also, this is an error that is occurring ONLY IN PRESTASHOP STORES VERSION 1.7, and that makes it impossible for us to enter the Back-office, showing an error 500 or the page goes blank. 

That's why we call it a critical mistake, for leaving the store inoperative.


To fix a HTTP 500 error on PrestaShop online store website:

You can activate your web host's FTP or CPanel error reports in your PrestaShop shop.

1.  From PrestaShop v1.4 to v1.5.2

i. Open config/config.inc.php

ii. On line 29, you will find this line: @ini_set('display_errors','off');

iii. Replace it with: @ini_set('display_errors','on');


2. PrestaShop v1.5.3 and later versions (including 1.6 and 1.7)

i. Open config/defines.inc.php

ii. On line 28, you will find this line: define('_PS_MODE_DEV_', false);

iii. Replace it with: define('_PS_MODE_DEV_', true);

Once error reports from the FTP or CPanel are activated, you can browse your store's front or back office to find out what the problem is.


More about Server error 500:

Error 500 means Internal server Error. Whenever a 500 error occurs, the task to return information by the server to the web browser will stop. 

Therefore, as we mentioned above, this is a critical error that would leave the website inoperative.

The 500 errors, as we noted above, are internal server errors and their origin may be in a programming code error on any item that is included and related to the request for information returned by the server to the web browser. 

Therefore, not all 500 errors come from the same source.

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Configure Varnish with Apache - How to do it


This article covers how to configure Varnish #cache on the #Apache server. Varnish is an HTTP accelerator and a useful tool for speeding up a server, especially during a times when there is high traffic to a site. 

It works by redirecting visitors to static pages whenever possible and only drawing on the virtual private server itself if there is a need for an active process.

#Varnish is a caching HTTP reverse proxy. It receives requests from clients and tries to answer them from the cache.


Where is varnish configuration file?

The Varnish configuration file will be located in the /etc/varnish directory in CentOS 7. 

To make Varnish work in front of Apache, you will need to set up some basic configurations. 

By default Varnish listens on port 6081 . 

You will need to change port 6081 to 80 so that website requests access the Varnish cache first.


What is varnish WordPress?

Varnish is a full-page cache and HTTP preprocessor which can be used to speed up requests for a WordPress site. 

Setting up Varnish is a technical task, as it requires installing and configuring a system package on a web server, rather than just installing a plugin.

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Jenkins setup with Docker and JCasC - Automate it now


This article covers how to perform Jenkins Configuration as Code (JCasC) method which can help us to automate the setup of Jenkins using Docker. 

This will automate the installation and configuration of Jenkins using Docker and the Jenkins Configuration as Code (JCasC) method.

Jenkins uses a pluggable architecture to provide most of its functionality. 

JCasC makes use of the Configuration as Code plugin, which allows you to define the desired state of your Jenkins configuration as one or more YAML file(s), eliminating the need for the setup wizard. 

On initialization, the Configuration as Code plugin would configure Jenkins according to the configuration file(s), greatly reducing the configuration time and eliminating human errors.


Just as the Pipeline plugin enables developers to define their jobs inside a Jenkinsfile, the Configuration as Code plugin enables administrators to define the Jenkins configuration inside a YAML file. 

Both of these plugins bring Jenkins closer aligned with the Everything as Code (EaC) paradigm.

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FastCGI Proxying in Nginx - How to implement it


This article covers FastCGI Proxying in Nginx. Basically, FastCGI Proxying in Nginx allows working with a great number of applications, in configurations that are performant and secure. 

FastCGI proxying within Nginx is generally used to translate client requests for an application server that does not or should not handle client requests directly.

Nginx has become one of the most flexible and powerful web server solutions available. 

However, in terms of design, it is first and foremost a proxy server. 

This focus means that Nginx is very performant when working to handle requests with other servers.

Nginx can proxy requests using http, FastCGI, uwsgi, SCGI, or memcached.


How do I know if #FastCGI is enabled?

If the variable is present and correctly set to /phpinfo. php/foobar? foo=bar, then either ISAPI or FastCGI is used. 

Look near the top of the output for Server API; it should be set to either ISAPI (which means ISAPI is being used) or CGI/FastCGI (which means FastCGI is being used, since we already ruled out CGI).


More about Fastcgi_read_timeout?

proxy_read_timeout is applied when nginx proxies via HTTP protocol (for example, if you used nginx to proxy the request to a server such as node.js ). fastcgi_read_timeout is used when nginx speaks to the other service using FastCGI protocol.


More about Keepalive_timeout in nginx?

The keepalive_timeout assigns the timeout for keep-alive connections with the client. 

Simply put, Nginx will close connections with the client after this period of time.


How does Nginx location work?

The location directive within NGINX server block allows to route request to correct location within the file system. 

The directive is used to tell NGINX where to look for a resource by including files and folders while matching a location block against an URL.


How do I start Nginx on Linux?

1. Nginx is a powerful server application that routes network traffic.

2. Nginx runs as a service on your server.

3. systemctl can be used to start and stop the Nginx service.

4. To force close and restart Nginx and related processes: sudo /etc/init.d/nginx restart.


What does #Nginx Rewrite do?

Nginx rewrite rules can be defined within your Nginx configuration file in order to change at least part or all of a URL. 

Usually, this is done for one of two purposes. 

First, if a URL has changed, using a rewrite rule will let the client know that the resource requested is in a different location.


How do I remove nginx welcome page?

If you removed default under /etc/nginx/sites-available and restarted nginx and the welcome page is still showing, then see if there is a default. conf under /etc/nginx/conf. d and delete it and then restart nginx.

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Best practices for Azure Cache for Redis


This article will guide you on some of the Best practices for Azure Cache for Redis. By following these best practices, you can help maximize the performance and cost-effective use of your Azure Cache for Redis instance.


1. Use Standard or Premium tier for production systems. The Basic tier is a single node system with no data replication and no SLA.

2. Remember that Redis is an in-memory data store. 

3. Develop your system such that it can handle connection blips because of patching and failover.

4. Configure your maxmemory-reserved setting to improve system responsiveness under memory pressure conditions.

5. Redis works best with smaller values, so consider chopping up bigger data into multiple keys.

6. Locate your cache instance and your application in the same region. Connecting to a cache in a different region can significantly increase latency and reduce reliability. 

7. Reuse connections. Creating new connections is expensive and increases latency, so reuse connections as much as possible. 

8. Configure your client library to use a connect timeout of at least 15 seconds, giving the system time to connect even under higher CPU conditions.

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NTFS partition failed to mount


This article will guide you on methods to resolve NTFS partition failed to mount error. 

Causes of NTFS partition failed to mount error:

1. File system errors

After using #NTFS drive in #Windows you have detached it without removing it safely. Therefore NTFS journal has not been emptied from temporary streams.

To fix the problem:

i. Open Disk Utility under #Mac OS X. 

ii. You will find it in Applications – Utilities.

iii. Choose NTFS partition on the left and find First Aid tab on the right. 

iv. Under this tab you will find Verify Disk option. 

v. Run Verify and then Repair.

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Troubleshoot Azure Cache for Redis timeouts


This article will guide you on how to troubleshoot Azure #Cache for Redis #timeouts. Azure Cache for Redis regularly updates its server software as part of the managed service functionality that it provides. 

Azure Cache for #Redis is a fully managed, in-memory cache that enables high-performance and scalable architectures. Use it to create cloud or hybrid deployments that handle millions of requests per second at sub-millisecond latency—all with the configuration, security, and availability benefits of a managed service.

This patching activity takes place largely behind the scene. During the failovers when Redis server nodes are being patched, Redis clients connected to these nodes may experience temporary timeouts as connections are switched between these nodes.


To help mitigate #Azure memory issues:

1. Upgrade the cache to a larger size so that you aren't running against memory limitations on the system.

2. Set expiration times on the keys so that older values are evicted proactively.

3. Monitor the used_memory_rss cache metric. When this value approaches the size of their cache, you're likely to start seeing performance issues. Distribute the data across multiple shards if you're using a premium cache, or upgrade to a larger cache size.


To fix #CPU bound on the server or on the client:

i. Check if you're getting bound by CPU on your client. High CPU could cause the request to not be processed within the synctimeout interval and cause a request to time out. 

ii. Moving to a larger client size or distributing the load can help to control this problem.

iii. Check if you're getting CPU bound on the server by monitoring the CPU cache performance metric. Requests coming in while Redis is CPU bound can cause those requests to time out. To address this condition, you can distribute the load across multiple shards in a premium cache, or upgrade to a larger size or pricing tier.

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Memcached DDOS attack


This article will guide you on methods to mitigate Memcached DDOS attacks which occur mostly by accident. To mitigate this attack, you can Disable #UDP, #Firewall #Memcached servers, and so on.

 DoS attack is a denial of service attack where a computer is used to flood a server with TCP and UDP packets. A DDoS attack is where multiple systems target a single system with a DoS attack. The targeted network is then bombarded with packets from multiple locations.

DDoS attacks are illegal under the Computer Fraud and Abuse Act. Starting a DDoS attack against a network without permission is going to cost you up to 10 years in prison and up to a $500,000 fine.

There are three essential security measures that all small businesses should take to protect themselves from #DDoS #attacks: Use a web application firewall (#WAF): The absolute best way to prevent a DDoS attack is through the use of a WAF that blocks bad traffic and prevents DDoS attacks from accessing your web server.

A Denial-of-Service (#DoS) attack is an attack meant to shut down a machine or network, making it inaccessible to its intended users. DoS attacks accomplish this by flooding the target with traffic, or sending it information that triggers a crash.

Different DDoS attack method:

1. UDP flood.

2. ICMP (Ping) flood.

3. SYN flood.

4. Ping of Death.

5. Slowloris.

6. NTP Amplification.

7. HTTP flood.

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Optimize Opencart website speed


This article will guide you on methods to optimize #OpenCart #Website to boost  and improve speed and pages load time.

OpenCart is one of the most recommended e-commerce platforms used by online merchants to set up their digital store. This PHP based platform provides users with an open source solution, allowing users to download and integrate any additional features to optimize one's e-commerce store.

Sometimes #websites load slowly because of the server. How this works is that your browser notifies your server asking it to send the data for your website over, so that the site can load. 

If there is an issue with the server, this will take longer than normal. The cause of slow servers usually lays with the web host.

To increase your Website page #speed:

1. Enable compression.

2. Minify CSS, JavaScript, and HTML.

3. Reduce redirects.

4. Remove render-blocking JavaScript.

5. Leverage browser caching.

6. Improve server response time.

7. Use a content distribution network.

8. Optimize images.

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Azure Cache for Redis client-side issues


This article will guide you on troubleshoot Azure #Cache for Redis client for issues and fix common Redis #error.

Azure Cache for Redis gives you the ability to use a secure open source Redis cache. It is a dedicated offering managed by Microsoft, to build highly scalable and responsive applications by providing you super-fast access to your data.

All #Redis #data resides in the server's main memory, in contrast to databases such as PostgreSQL, Cassandra, MongoDB and others that store most data on disk or on SSDs.

The way to test for this in Redis is to simply query the key. If the key is empty, populate it. If it is a string use get (or exists).

To configure a storage account for your cache metrics:

1. In the Azure Cache for Redis page, under the Monitoring heading, select Diagnostics.

2. Select + Add diagnostic setting.

3. Name the settings.

4. Check Archive to a storage account.

5. Select Configure to choose the storage account in which to store the cache metrics.

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More about Engintron cPanel


This article will guide you on how to #install #Engintron in #cPanel & fix relating #errors.  Engintron is a third-party plugin to integrate Nginx on cPanel servers. 

Engintron integrates Nginx into cPanel so you can enjoy amazing performance for your sites, without having to sacrifice important hosting features found in cPanel.

Engintron is totally free to use!

The way Engintron sets up Nginx inside your cPanel is a lot like how the popular #CloudFlare CDN works. Nginx (like CloudFlare) directly serves all static content like CSS, JS, images etc. instead of your actual web server, thus lowering the load on your cPanel server.


Engintron is the easiest way to integrate Nginx to your cPanel server:

1. Installation process is not very complicated for Engintron. 

2. Also, installation and updates are very fast, they take only a few seconds. 

3. Engintron is using the official repositories for Nginx, all Engintron software is updated whenever cPanel is updated. If something has changed on Engintron and you need to re-install it, you can install it on top of the previous installation. You don't need to uninstall it first like other Nginx installer plugins for cPanel. It works from CentOS 5 up to CentOS 7. Engintron has an app dashboard inside WHM. 

4. The interface has basic controls for Nginx, Apache, MySQL. These controls allow you to edit various configuration files. Inside the Engintron app dashboard you’ll also find some utilities to monitor things like Nginx access & error logs, check processes on your server or see incoming traffic on port 80. It doesn’t require Nginx or Apache host synchronization when adding new domains via cPanel. 

5. Also, Engintron is released under the GNU/GPL license and is 100% open source.

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Redis as a Cache for MySQL with PHP on Ubuntu


This article will guide you on steps to use #Redis to cache #MySQL data with #PHP on #Ubuntu 20.04.  Redis, which stands for Remote Dictionary Server, is a fast, open-source, in-memory key-value data store for use as a database, cache, message broker, and queue. 

To Connect to Redis through the SQL Gateway:

1. In MySQL Workbench, click to add a new MySQL connection.

2. Name the connection (CData SQL Gateway for Redis).

3. Set the Hostname, Port, and Username parameters to connect to the #SQL Gateway.

4. Click Store in Vault to set and store the password.

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Data Loss through Partial loss of keys in Azure Cache for Redis


This article will guide you on the different methods to fix data loss in #Azure #Cache for #Redis which can happen due to a number of reasons like Redis instance failure, incorrect #database selection, and so on. 

Redis server saves all its data to HDD from time to time, thus providing some level of persistence. It saves data in one of the following cases: automatically from time to time. when you manually call BGSAVE command.

Redis does not use #tables, and stores data in #memory, and is not limited by the hard #disk I / O speed when reading and writing #data, so the speed is extremely fast.

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How to monitor Azure Cache for Redis


This article will guide you on how to monitor Azure Cache for Redis. Azure Cache for #Redis uses #Azure Monitor to provide several options for monitoring #cache instances. These include view metrics, pin #metrics charts to the Startboard, customize the date and time range of monitoring charts, and so on.

To Use Azure Redis Cache:

1. Log into Azure port, go to #Databases >> Redis Cache.

2. Create a news Redis Cache.

3. Get the Access Keys to connect with the newly created Redis Cache.

4. Install the #StackExchange. 

5. You can add Redis Cache connection string into the appsettings.

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SSLSessionCache cannot occur within VirtualHost section


This article will guide you on the steps to resolve #SSLSessionCache cannot occur within #VirtualHost section issue. Basically, SSLSessionCache is a file-based #cache of established #SSL sessions.

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Microsoft SQL Server Error 701


This article will guide you on the steps to resolve #SQL Server #Memory pressure or insufficient #memory issue which can happen due to huge data load or other memory-intensive #operations that lead to a 701 #error in the SQL server.

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Cleanup tasks with Docker How to run it quickly


This tutorial will guide you on how to perform cleanup tasks with Docker which involves keeping the Docker clean to solve the server space issue that is especially important when Docker is running as a virtual machine.

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Enable or Disable cached mode in outlook


This article will guide you on how to enable/disable cached mode in Outlook which allows Outlook to store the mailbox data in your Computer.

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Fix high memory usage by Metafile on Windows Server 2008 R2


This guide will help you to fix high memory usage issue by Metafile on Windows Server 2008 R2.

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Steps to install OpenLiteSpeed on CentOS


This article will guide you on how to perform installation of OpenLiteSpeed on Centos Server.

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Nginx FastCGI caching


This article will show you how to configure FastCGI cache with Nginx since it can cache the HTML pages generated from a PHP code thereby eliminating the PHP/database requests.

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How to install and configure cacti on Linux


Steps to install and configure Cacti which is network monitoring tool which displays server efficiency information in form of a personalized graph.

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How to fix docker Error response from daemon unable to remove volume


Server users experience Docker error such as "error response from daemon: unable to remove volume" when trying to remove the volume of a container in Docker.

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Fix Memcached Not Found error


Here at IbmiMedia, we have dealt with numerous Memcached related errors as part of our Server Support Services for our clients.

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