Applies to:

Plesk 12.5 for Linux

Symptoms

1. Plesk is not accessible due to stopped sw-engine service.
2. sw-engine cannot be started:

# service sw-engine start
/usr/sbin/sw-engine-fpm: error while loading shared libraries: libxmlrpc_cpp.so.4: 
cannot open shared object file: No such file or directory

     3. Library libxmlrpc_cpp.so.4 is missing from the server:

# ls -l /usr/lib64/libxmlrpc_cpp.so.4*
#

4. Package xmlrpc-c-c++-1.16.24-1210.1840.el6.x86_64.rpm is not installed:

# rpm -qa | grep xmlrpc
xmlrpc-c-1.16.24-1210.1840.el6.x86_64
xmlrpc-c-1.16.24-1210.1840.el6.i686
plesk-php70-xmlrpc-7.0.9-centos6.16072211.x86_64
xmlrpc-c-c++-1.16.24-1210.1840.el6.i686

Cause

Missing libxmlrpc_cpp.so.4 library.

Resolution

1. Download xmlrpc-c-c++- package for the Linux distribution installed, e.g. for Centos6, 64-bit:

# wget ftp://fr2.rpmfind.net/linux/centos/6.8/os/x86_64/Packages/xmlrpc
-c-c++-1.16.24-1210.1840.el6.x86_64.rpm

2. Install such package:

# rpm -ivh xmlrpc-c-c++-1.16.24-1210.1840.el6.x86_64.rpm

3. Start sw-engine service

# service sw-engine start

Block Storage and Object Storage are two methods of data storage. Let’s see in detail what it is and what services they offer.

It is very important to understand what the Block storage and Object storage is as they play a key role when it comes to optimizing the use of Cloud services, particularly in storage and the creation of local infrastructure projects. See below what it is in the detail.

Block Storage

The block storage is a storage type of data used in environments of Storage Area Network (SAN), which provides data storage volumes in those blocks. Each block is configured as a single hard disk and is configured as a single hard disk and is configured by the administrator. These blocks are controlled by the operating system and are generally called by the Fibre Channel (FC), Fibre Channel over Ethernet (FCoE) or iSCSI protocols.

Because volumes are treated individually as hard drives, the Block Storage works well by storing a variety of applications such as file systems and databases. While storage devices tend to be complex and expensive, the Block Storage tends to be more flexible and provides better performance.

The block storage devices offer a storage capacity fixed. Each volume can be treated as an independent disk drives controlled by an external source. This device can be mounted by the host operating system as if it were a physical disk. The most common examples of Block Storage are San, iSCSI and local disks. They system of Block Storage is the one most commonly used for most applications and can be local or via the network. The devices are usually formatted with a file system FAT32, NTFS, EXT3 and EXT4.

When using the Block Storage?

The block storage is ideal for databases as they require high I/O performance and low latency connections feature. It can be used for RAID volumes where multiple disks are combined. Each application that needs processing as Java, PHP and .Net need of Block Storage, ditto for critical applications such as Oracle, SAP, Microsoft Exchange and Microsoft SharePoint.

Object Storage

The object storage is a tool for archiving data between cloud computing.

Object storage and block storage represent the two storage services in the cloud. Above we focused on the Block storage; we have seen how it works and what the solutions available in the Cloud are. Now, we will focus, instead, on the object storage.

The Object Storage is an architecture that manages the data as objects, in contrasts to other storage architecture like file system, which provides the management of data according to a hierarchy of files treated as blocks within individual sectors. Each Object typically includes the data, a variable amount of metadata and a globally unique identifier. The Objet Storage can be implemented in multiple levels and includes the device level, the system level and the interface level.

The data held on devices Object Storage can be accesses directly through the API or http/https, can store any type of data, photos, videos and log files. This type of storage ensures that data is not lost. Data stored in this way can be replicated across multiple data centers and offer simple interface for Web access.

Object storage applications

A simple to use the Object Storage may be represented by the use of service as a means of storage for developers who work with large quantities of media and need unlimited storage. The Object Storage, in fact, become gradually more and more attractive as soon as the data to be archived increased dramatically, as happens to with eNlight Cloud Services that allow users to upload media files (especially video).

Storage of unstructured data such as music, pictures and video, but also backup, database dump and log files are the most common cases of use of the Object Storage.

Summary:

Today, we will see two performance models in eNlight Cloud, these two different models means that you can choose an option that going to be most suiting to your requirements.

In eNlight each performance model is based around the way that cache memory and RAM are used (Read More: How many types of Cache do you know?). Cache memory can be seen as being an extension to RAM, which is primarily used by computers to access information more quickly that can be done so from disk.

Under some circumstances the cache memory can grow unhealthily large and the result of this is that a majority of the RAM ends up being reserved for cache purposes; this is the main design of most Linux distributions because it improves the execution speeds of certain commands that have been executed previously.

The amount of RAM that is used for the purpose of cache memory can have huge implications on the performance of a Virtual Machine.  The two performance levels that we offer so that you are able to fully enjoy the high levels of performance that eNlight offers are:

• The economy-based model – With this model there are limits set on the size to which the cache memory on the RAM can grow. As there is a limit on the size of the cache, there is often no need to increase the size of the RAM.  The economy-based model isn’t designed to offer high levels of performance because this impeded by data being accessed from the disk rather than from the memory.  As this model is focused on limiting the size of the cache, it is the more affordable of the two models and is targeted more at customers running applications and database that are small and don’t require high performance benchmarks.

• The performance-based model – eNlight offers the performance-based model for customers that have web applications and databases that are subject to high levels of traffic and where large amounts of data are being processed constantly. For these customers we suggest a solution that uses a considerably large cache size for the storage devices; by doing this we can increase performance by avoiding the repetitive fetching of the same information from drives several time over and so that future requests can be handled immediately.

There are certain scaling limitations for you to be aware of:

• Linux VMs can have their CPUs scaled from 1 CPU to 24 CPUs
• The scaling capacity for Linux VMs runs from 512MB to 64GB with a security restriction in place at 16GB
• Windows VMs can have their RAM scaled anywhere between 1GB and 4GB
• Windows VMs come with 4 CPUs as standard.

Summary

Auto-scalability is one of the flagship features of eNlight Cloud is designed to provide Cloud Virtual Machines with additional resources when their base specifications begin to get exhausted under the loads that they are placed under.

Presentation

With eNlight the computing resources that you’ve allocated to your Cloud VMs can be automatically increased when the performance of the VM could be called into question, with CPU and RAM being two examples of resources that can be managed in this way. So that you don’t end up with any unexpected huge bills, limits can be placed on the level to which resources are automatically scaled so that you don’t go over your budget.

The best thing about auto-scaling from eNlight is that all of this is done without the need to reboot the VM so not downtime is ever incurred! The platform is one of the most intelligent around and when it detects that a VM is in need of extra power, more resources will be pulled from the central pool that all VMs in the Cloud take their power from. As auto-scaling responds automatically to demand, you will only be billed for periods of high-usage, as the specifications of your VMs will return to their pre-determined level once the load decreases.

How exactly scaling works?

Resources are scaled up and down by eNlight as a percentage of resource consumption patterns. Scaling is done steadily, but is also fast and effective at the same time, as is the scaling down. As the scaling down is performed, the resources allocated originally are moved off your VMs and allocated elsewhere, often during off-peak hours as this is when demand is going to be at its lowest. This has proven to be popular because it means that businesses using eNlight are truly only ever paying for what they are using and ensures that redundant resources aren’t costing them money.

Scaling Storage?

Although disk scaling isn’t available in eNlight Cloud, but we do offer a feature known as Elastic Storage that means you can add multiple disks to a single VM. These disks can be attached and detached on the fly and between VMs, without any data loss. This is why we believe that eNlight is one of the best options available options available for Disaster Recovery hosting.

The Main Features of Auto-Scaling

• Computing resources are scaled up automatically and seamlessly as per demand
• These resources are then scaled down as demand reduced to minimize costs to the customer
• Maximum limits can be set for the scaling of CPU power, RAM and bandwidth to ensure that you remain within budget
• Auto-scaling is individual to each VM so that it can be disabled if necessary
• Encourages efficient use of resources without impacting on system performance
• This is a standard feature of the eNlight Cloud so that you don’t have to pay any additional fees to access it.

Stay tuned, as we will discuss Performance Models in eNlight Cloud next week!

Summary: What keeps eNlight Cloud Computing on topmost? eNlight is a Cloud Service that is easy to use and easy to set-up if you understand its many facets and features.

1. Unconstrained Resources – eNlight cloud virtual server has virtually unlimited resources because of the architecture of the Cloud Environment. Whilst you can purchase a VM with the base specifications of your choice, you can also enable auto-scaling that will automatically provision additional resources to your server when the base resources are approaching exhaustion.

You can place a limit on the level to which your resources are scaled so that you have full control of your costs as well! Whilst these limits can be changed at any time, you should always consider that the Cloud will always have resources available on demand and so this can deliver a massive performance boost when needed.

2. Instant Virtual Machine Provisioning – Once you have paid for your VMs, they will be provisioned in a matter of seconds so that you can get started with them when you’re ready. If you’re migrating physical servers into the eNlight Cloud then you will be thankful for these fast provisioning times because it will reduce the turnaround time for each migration.

You will also find that you won’t have to waste time installing a majority of applications that we have a number of pre-defined virtual machine templates available for you to use! When setting up a VM, simply choose the templates that you would like to use and your VM will be configured using the OS of your Choice.

3. Flexibility – eNlight Cloud is one the best Cloud environments available in the hosting industry, irrespective of whether you are a beginner or a business looking for a more stable hosting solution. You can manage your needs on a level that hasn’t been available previously, with Dynamic resources being available automatically. Whilst web developers can use their VMs for the development and testing of web applications, SMEs may see a benefit in transitioning their physical servers into the Cloud. The billing estimator will allow customers to see what their budget can buy them, whilst limiting resources to their precise requirements will allow them to save money where possible.

4. Web-based Control Panel and Console Access – eNlight VMs are managed through the web-based control panel that all customers are provided with access to. Using the web based control panel you can create ‘New’ VMs and ‘Modify’ or ‘Delete’ existing ones. You will also be able to view your previous invoices and credit your account with additional funds to finance your eNlight endeavors.

In addition to this you can also view the current resource usage of your virtual machines so that you identify if there is a need to purchase additional resources; if that need exists then these orders can also be placed through the control panel! You can also use the control panel to access your VM’s console, regardless of whether you are using Windows or Linux.

5. Cloud Environment – eNlight is a Cloud hosting platform that is designed to offer the ultimate in security and reliability. Centralized storage units and backups servers guarantee that your services will still be available in the event of hardware failure in any part of the Cloud cluster. Some the core features that eNlight Cloud is based around include:

a. Servers based around the latest high-end Intel Xeons CPUs.
b. High IPOS with redundant 10Gb storage arrays.
c. High quality Bandwidth.

6. Zero Downtime* – Auto-scaling in eNlight Cloud guarantees that your VMs are never going to crash because of a lack of resources. Though you think that your base resources may be more than enough to fulfill demand for the time being, you can never predict load spikes and it is these that often bring down websites. ENlight is entirely based around a cloud architecture that pretty much dispels any potential hardware or software failure.