Sep 042016
 

Based on Changing a RAID-10 into a RAID-5

It is usually assumed that the best HDD organization on a backup server is a RAID5, since it provides a fairly good price/volume. Unfortunately, increasing of disk count affect to some RAID5 disadvantages, in particular the in reliability and recovery speed. For example if the server has RAID5 of 6 (six) SATA disk drives (even it’s reliable enough, such as WD Re), with one disk replacement, array recovery time is about 10 hours (in my case). At the recovery time reservation is absent, the load on the disks are increased, that increases the probability of failure of the remaining disks, and if all the disks have same series, the probability of another disk will deteriorate during the recovery, increase even more.
In this regard, it was decided to convert the existing disk array from RAID5 to RAID10 with the addition of two drives, that in theory should lead to increasing of server performance and improving reliability.

Continue reading »

Feb 272016
 

When you try to access HP ILO2 console via some new version of OpenSSH you have error.
For OpenSSH v.6
# ssh ilouser@iloserver
Received disconnect from iloserver: 2: Client Disconnect

Solution: add option -o MACs=hmac-sha1 to ssh:

# ssh -o MACs=hmac-sha1 ilouser@iloserver
ilouser@iloserver's password:

For OpenSSH v.7
# ssh ilouser@iloserver
Unable to negotiate with UNKNOWN: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1

Solution: add option -o KexAlgorithms=diffie-hellman-group1-sha1 -o MACs=hmac-sha1 to ssh:

# ssh -o KexAlgorithms=diffie-hellman-group1-sha1 -o MACs=hmac-sha1 ilouser@iloserver
ilouser@iloserver's password:

Feb 272016
 

From Pinoy UNIX Administrations

There are times when you want to have a quick access to the remote console of a server like HP’s ILO but you don’t want (not able) to open a web browser just to access it. But there is an ability to access it via SSH (text console only).

  1. Open a ssh connection to the ILO’s IP address.
    # ssh ilo_admin@ip_address

  2. Enter your ILO admin account and password. After that you will see the ILO prompt.
    hpILO->

  3. To access the remote console of the server at the ILO prompt type “TEXTCONS”
    hpILO->TEXTCONS

  4. You will be presented with the Login: console. Enter your root or user account of the server to gain access.
    Login:
Apr 182014
 

Sometimes when you upgrade firmware of access points (AP) through the UniFi controller interface, AP hung in Upgrading state (eg UniFi AP PRO).
When you restart AP, it does not change state and AP does not reach.
In this case, you need to upgrade AP firmware via command line.
It is assumed the server is installed on Linux

  1. Determine controller version and firmware code:
    Version: execute command on the server

    ls -l /usr/lib/unifi/dl/firmware/BZ2/
    

    resulting directory is version number

    Firmware code determined by the table:
    Continue reading »

Aug 072013
 
  1. In file /etc/yum.repos.d/CentOS-Base.repo in section [base] set enabled=1
  2. sed -i 's/enabled=0/enabled=1/g' /etc/yum.repos.d/CentOS-Base.repo
  3. For XenServer 6.2, 6.5 in file /etc/yum.repos.d/Citrix.repo in section [citrix] set enabled=0
  4. sed -i 's/enabled=1/enabled=0/g' /etc/yum.repos.d/Citrix.repo
  5.  rpm -Uvh http://dl.fedoraproject.org/pub/epel/5/$(uname -i)/epel-release-5-4.noarch.rpm
     cd /tmp
     wget https://yum.puppetlabs.com/el/5/products/$(uname -i)/puppetlabs-release-5-10.noarch.rpm
     rpm -Uvh puppetlabs-release-5-10.noarch.rpm
     yum install puppet
    

    set up /etc/puppet/puppet.conf, after that:

     chkconfig puppet on
     /etc/init.d/puppet start
    

I Also recommend using a xs_patcher to make XenServer up to date.

Aug 072013
 

Warning: all operations are carried out only with the first two RAID partitions, the third partition is not changed

Due to the fact that the standard update is a XenServer installation of the new XenServer with virtual machines preservation, with the loss of all the changes that were made manually on the server (installed software, changing / adding settings through the console, etc.), the update is the new XenServer installation and connection of the old virtual machines.

Based on: http://support.citrix.com/article/CTX120962

  1. Backup all VM, manually:
    xe vm-export vm=vm_name filename=backup_fiule_name compress=true
    ...
    xe pool-dump-database file-name=dump_name.dump
    

    or with XENBack

  2. VM metadata export
    xe vm-export metadata=true --multiple filename=VMEXPORT

    Warning: store all files VMEXPORT… to another computer/data store/etc

  3. Continue reading »

Apr 282013
 

Objective: Move the Windows virtual machine, you can change when you transfer the resources allocated system
Problems: Converting using XenConvert whole system in OVF format can be imported only through the XenCenter and does not always work
Warning: this work only on EXT storage (not LVM)

  1. Install XenConvert on Windows
  2. Export appropriate volumes using XenConvert in the format VHD (it is recommended to export only drive C, just copy the other disks)
  3. Copy the VHD file to a location accessible from the XenServer
  4. Download and install the vhd2xen.i686 utility on XenServer
  5. Import VHD disk in XenServer:
    /usr/lib/Acronis/VHD2XEN/vhd2xen.sh [VHD file]
  6. Create a virtual machine In XenCenter from a template corresponding to the exported system
  7. Remove all the created discs In the newly created virtual machine and attach imported disk
  8. Start the virtual machine and fix the settings in Windows, if necessary