FAQ

How do I choose a storage type?

Three types of disks are available for UCloud Global: Cloud Disk (UDisk), Local Common Disk, and Local SSD Disk.

Cloud Disks have 3 redundant backups, high reliability, and support second-level recovery after a downtime. Local disks offer stronger IO performance but come at a relatively higher cost.

The above disk types may not be available in some data centers or may have application restrictions due to inventory limitations. If you cannot select the required disk, please consult your account manager.

For specific performance and pricing comparisons, please refer to UHost Disk Introduction

Is the firewall set in the control panel mapped to the system’s iptables?

This is a standalone firewall, different from the iptables in the user’s system. We recommend using the backend firewall, which achieves the same effect as iptables but is more convenient to operate.

What should I do if the software I want to install cannot be found in the software sources provided by UCloud Global?

If your UHost has a public IP, you can install third-party software sources. If a source is widely used, we will add it to the default software source cache.

If the software is not available in third-party sources, you can download the source code and compile it manually.

If there is no public IP, please contact us, and we will continuously update the software source content.

How can the best performance be achieved when using MySQL on an SSD UHost?

When using a MySQL database on an SSD UHost, the following optimization is required: set innodb_io_capacity to 2000 (this configuration is not needed if using MyISAM).

How to migrate files to UHost?

Pack files locally on the original server and then transfer them to the UHost using methods such as scp or ftp.

Does a UHost incur charges when it is shut down?

Postpaid UHosts do not incur charges for CPU, memory, and network enhancement when shut down. UHosts of other payment types will still be charged as usual when shut down, so please ensure to delete UHosts that are not in use.

How to enlarge the SWAP partition?


swapoff -a
rm /swapfile
dd if=/dev/zero of=/swapfile bs=1M count=1024
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

There is a test page on the UHost, but why is the speed very low when using 17ce to get this page?

The Get request of 17ce is a concurrent test. If the bandwidth is only 2M, each node of 17ce (about 50 nodes) can only be allocated tens of K, so it will be relatively slow.

How to handle the slow yum update in CentOS?

Change 6.3 (or other version numbers) in /etc/yum.repos.d/CentOS-Base.repo to $releasever, and then run yum update.

Gem is often slow and unusable, how can I switch it to the taobao source?


gem sources --remove http://rubygems.org/
gem sources -a http://ruby.taobao.org/
gem sources -l  # make sure only ruby.taobao.org is available.
gem install foo

I just conducted a high-concurrency test, but now the UHost is unreachable. Why?

The data center firewall may have identified this as an attack and blocked access from your local IP. If this occurs, please contact technical support.

Why is uploading files to the UHost so slow?

We do not impose speed limits on file uploads to UHosts. If the speed is slow, check whether your local ISP restricts upload bandwidth (e.g., Shenzhen’s ordinary ADSL limits upload speed to 512 kbps).

How to use the two IPs in a dual-line data center for intelligent resolution?

We recommend using DNSPod. After logging into the backend, enter the following information:

Host Record

The host record is the domain name prefix. Common uses are: www: Resolved domain name is console.ucloud-global.com @ : Directly resolves the main domain nameucloud-global.com * : global parsing, matching all other domain names*.ucloud-global.com

Record Type

Here we do A record, select A.

Line Type & Record Value

First line: Select Default for the line type, and enter the Telecom IP in the record value.

Second line: Select Unicom for the line type, and enter the Unicom IP in the record value.

How to modify the DNS address to DNSPod on Aliyun?

Fill in the 2 DNS short addresses of DNSPod (corresponding to 6 servers)

f1g1ns1.dnspod.net

f1g1ns2.dnspod.net

Can the UHost update the kernel?

It can be updated. Like a physical server, use yum update or apt-get upgrade linux-image.

On CentOS, how do I create a custom kernel rpm package?

Confirm the current kernel version number and download the corresponding SRPM package:


#Confirm the current version number
uname -r

# Go to valut.centos.org to find SRPM and download
# Points to note
# (1) Confirm whether the plus version of the kernel is used. If so, the SRPM is in /centosplus/Source/SPackages/
# (2) Non-plus versions are in the following two directories: /updates/Source/SPackages, /os/Source/SPackages
wget http://vault.centos.org/6.4/updates/Source/SPackages/kernel-2.6.32-358.14.1.el6.src.rpm

Install SRPM and related RPM tools:


# Install SRPM
rpm -ivh kernel-2.6.32-358.14.1.el6.src.rpm

# Install related RPM tools
yum install rpm-build redhat-rpm-config patchutils xmlto asciidoc elfutils-libelf-devel zlib-devel binutils-devel newt-devel python-devel perl-ExtUtils-Embed hmaccalc rng-tools kernel-firmware

# Start the rngd service to provide enough entropy value 
cat /dev/null >/etc/sysconfig/rngd 
echo 'EXTRAOPTIONS="--rng-device /dev/urandom"' >/etc/sysconfig/rngd 
service rngd start

Generate kernel source code, and use diff to generate patch files:


# Generate kernel source code
cd ~/rpmbuild/SPECS
rpmbuild -bp kernel.spec

# Modify and generate diff file
cd ~/rpmbuild/BUILD
cp -r kernel-2.6.32-358.14.1.el6 kernel-2.6.32-358.14.1.el6.mine
diff -urpN kernel-2.6.32-358.14.1.el6 kernel-2.6.32-358.14.1.el6.mine > this-patch-to-fix-that-bug.patch

# Copy the patch to SOURCES
cp this-patch-to-fix-that-bug.patch ~/rpmbuild/SOURCES

# Clean up
rm -rf ~/rpmbuild/BUILD/kernel-2.6.32-358.14.1.el6*

Modify the SPEC file to generate a new kernel RPM package:


# Find the following lines, add one after
# Source84: config-s390x-generic-rhel
# Source85: config-powerpc64-debug-rhel
# Source86: config-s390x-debug-rhel

# New line
Source87: this-patch-to-fix-that-bug.patch
Patch001: this-patch-to-fix-that-bug.patch

# (Optional) Modify the changelog, find the %changelog line, and then insert the line:
* Tue Aug 03 2013 Your Name<yourname@company.com> [2.6.32-358.14.1.el6.centos]
  - [XXX] path to fix that bug

Pack to generate a new kernel RPM package:


# Execute SPEC. As the generation process is very long, please be patient.
# Before execution, carefully review the above steps to avoid errors and start over
rpmbuila -ba kernel.spec

# Several RPM packages will be generated, and the most important of which are as follows. Use rpm -ivh to install
# kernel-2.6.32-358.14.1.el6.x86_64.rpm
# kernel-devel-2.6.32-358.14.1.el6.x86_64.rpm
# kernel-headers-2.6.32-358.14.1.el6.x86_64.rpm

How to resolve dependency issues with kernel-devel when installing software packages on CentOS?

To ensure the stability of the kernel, by default, we added exclude=kernel* centos-release* in the yum configuration file /etc/yum.conf, which can prevent the kernel-related stuff from being updated unintentionally when installing software packages. If you really need to install this software package, you can comment this line of code in /etc/yum.conf.

What is the /usr/bin/uga program? What is the uga process in the host?

UGA is a built-in proxy program provided by UCloud Global for the host. It is only used to help users perform automated operations in conjunction with host console functions to improve user experience. UGA cannot be used to view, add, delete, or modify user files.

How to activate Windows Server on UHost?

Windows UHosts created on UCloud Global are activated by default, and users do not need to operate them. Refer to KMS Activation Description

If for special reasons, you need to manually activate it, then the steps are as follows:

1.KMS address

First, define the KMS address ($kms_name) of each data center. Step 4 will use $kms_name, please use the corresponding address instead. For example, the address of the North Zone E is hb06.kms.ucloud-global.com. If you need other zone addresses, please contact technical support.

Enter command directory

Open cmd as administrator -> cd C:\Windows\system32

Clear the secret key and restart

Execute cscript.exe slmgr.vbs /rearm to clear the unified key, and restart the operating system after completion.

Configure KMS

Open cmd with administrator -> cd C:\Windows\system32. Execute cscript.exe slmgr.vbs /skms $kms_name (see step 1)

Activate Windows

Execute cscript.exe slmgr.vbs /ato to activate windows