Article ID: 126801, created on Sep 3, 2015, last review on Jun 17, 2016

  • Applies to:
  • Virtuozzo 6.0

Issue date: 2015-09-03

1. What's Included in This Update

The new packages for Virtuozzo (formerly Parallels Cloud Server) 6.0 introduce new features and provide stability and usability fixes for virtual machine and Container management tools and Virtuozzo Storage.

2. New Features

  • Backup/restore API for block devices. The new API functions allow developing third-party backup solutions for Virtuozzo virtual machines and Containers.

  • Virtual machine CPU limit now takes into account hardware virtualization overhead. The new '--vm-cpulimit-type' parameter enables Node administrator to apply CPU limit to specific virtual machine threads: both service and activity or just activity.

  • Guest filesystem usage reporting. The new 'guest.fs*' performance counters provide usage statistics of virtual machine and Container filesystems. The data provided includes filesystem's total size, free space, name (as seen from inside the guest), and indices of disks on which the filesystem resides. The data can be obtained with the 'prlctl statistics centos7 --filter "guest.fs*" --loop' command.

  • Periodic NTP time synchronization is now enabled by default during Virtuozzo installation.

  • Linux kernel AIO limit virtualization. Global kernel variables 'aio_nr' and 'aio_max_nr' are now virtualized as 'fs.aio-nr' and 'fs.aio-max-nr' for Containers and Hardware Nodes. Container owners can set their own 'fs.aio-max-nr' limits isolated from Node's and other Containers' limits. The 'fs.aio-nr' variable shows current AIO usage calculated per Container and Hardware Node.

  • Added support for more guest operating systems. The following guests are now available: openSUSE 13.2, Fedora 21, Debian 8, Ubuntu 14.10, Ubuntu 15.04.

  • The pcompact utility can now defragment data blocks. It can be controlled with the 'DEFRAG' parameter in the '/etc/vz/pcompact.conf' configuration file.

  • VirtIO is now default network adapter for most Linux guests.

3. Bug Fixes

  • ploop could get stuck inside ploop_make_request() causing Node to hang (#PSBM-29066, #OVZ-6293, #OVZ-6392)

  • By default kdump was configured to store crash dumps on '/' which could be too small. Now the partition with the most free space is automatically chosen for crash dumps. (#PSBM-31922)

  • Removing a snapshot of a virtual machine with split disks could get that virtual machine stuck in the 'del_snapshot' state. (#PSBM-32164)

  • ext4 filesystem over ploop device could get corrupt due to hard reset. (#PSBM-32381)

  • Under certain network workload, Container checkpoint/restore operations could result in conntrack duplication which could prevent online migration of said Container. (#PSBM-32411)

  • Container could not be restarted after attempting to enable quota for it with the 'vzctl set quotaugidlimit --setmode restart' command. (#PSBM-32894)

  • Attempt to join a cluster could fail with an error message "A cluster with this name already exists". (#PSBM-32970)

  • In certain circumstances, virtual machine disk could become corrupt. (#PSBM-33127)

  • Soft lockup in 'cgroup_kernel_close()'. (#PSBM-33300)

  • Kernel could crash in 'attach_task_by_pid()' when tasks exited. (#PSBM-33381)

  • CPT image compatibility was broken in 042stab108.x kernels. As a result, received but nondelivered TCP packets saved into CPT image could, in certain circumstances, lose TCP flags during restore on 042stab108.x kernels. This resulted in incorrect processing of restored packets and could cause unexpected kernel warnings or lead to issues in userspace applications. (#PSBM-33549, #OVZ-3237)

  • Fixed the reason of invalid warning "ida_remove called for id=0 which is not allocated." (#PSBM-33789, #OVZ-3117)

  • The 'VE_PARALLEL' option in '/etc/vz/vz.conf' was ignored on server reboot. (#PSBM-34836)

  • Dispatcher could stop itself and all virtual machines if vzmdest failed during migration. (#PSBM-34986)

  • ploop journal could get stuck in '__block_write_full_page()' causing Node to hang. (#PSBM-35095)

  • After conversion of a third-party virtual machine to Virtuozzo with Virtuozzo Storage, the resulting virtual machine could have split disk. (#PSBM-35286)

  • Temporary files remained after 'prlctl backup' operation was cancelled. (#PSBM-35292)

  • The '--backup-timeout' option for prlsrvctl was renamed to '--idle-connection-timeout' for clarification. (#PSBM-35307)

  • In certain circumstances, Hardware Nodes with 108.x kernels could crash. (#PSBM-37612)

  • rsyslogd was not allowed to dump Container-related kernel messages inside Container. (#OVZ-2693)

  • UDP socket reference count bugs in the pppol2tp driver. (#OVZ-3117)

  • Virtual devices state (AHCI, VirtIO) could become corrupt on target node during migration.

  • Virtual block layer was optimized for speed.

  • A number of other issues. (#PSBM-19258, #PSBM-24412, #PSBM-25446, #PSBM-27264, #PSBM-29522, #PSBM-29760, #PSBM-29763, #PSBM-30460, #PSBM-30636, #PSBM-30732, #PSBM-30787, #PSBM-31266, #PSBM-31452, #PSBM-31706, #PSBM-31708, #PSBM-31727, #PSBM-32613, #PSBM-32710, #PSBM-32791, #PSBM-32795, #PSBM-32803, #PSBM-32826, #PSBM-33074, #PSBM-33163, #PSBM-33333, #PSBM-33381, #PSBM-33472, #PSBM-33651, #PSBM-33730, #PSBM-33781, #PSBM-33804, #PSBM-33924, #PSBM-33996, #PSBM-34041, #PSBM-34227, #PSBM-34385, #PSBM-34560, #PSBM-34677, #PSBM-34689, #PSBM-34697, #PSBM-34813, #PSBM-34901, #PSBM-35308, #PSBM-35323, #PSBM-35380, #PSBM-37910, #PSBM-38748, #PSBM-39148)

4. Known Issues

  • The 'prlctl' utility does not support some of the Container operations supported by 'vzctl' in the previous versions of Virtuozzo Hypervisor. To perform such operations, use the 'vzctl' utility instead of 'prlctl'.

  • The offline management feature does not work for Containers operating in the bridged networking mode. For details, see the KB article at /en/111356.

  • The offline management feature might not work for running virtual machines that operate in the bridged networking mode. The reason for this is that the destination MAC address in incoming offline management packets is changed when the packets are processed on the Parallels server. As a result, the processed packets contain a source MAC address different from the destination one in incoming packets and might be dropped by your router. To solve the problem, reconfigure the router to accept packets with the same IP address but different MAC addresses. As an alternative, you can set the network adapter of a virtual machine to operate in the host-routed mode.

  • Setting encrypted passwords for containers that run Ubuntu 10.04 is not supported. To work around the problem, set the password in plain text. For more details, see /en/114759 (#PSBM-14886).

  • Cannot establish IPsec connections from Virtuozzo Hardware Node to Containers. For more information, see /120008.

  • Containers with multiple virtual hard disks cannot be backed up or restored via Virtual Automation or using the 'vzabackup'/'vzarestore' commands.

  • An issue in the e1000 network driver may cause network on Windows Server 2012 R2 Update 1 virtual machines to stop working. For more details, see /en/123253.

  • Converting a Hyper-V virtual machine to a Virtuozzo virtual machine may fail. To work around the problem, use the '--allow-no-os' option when converting the virtual machine. (#PSBM-7201)

  • Creating a virtual machine in Virtuozzo 6.0 set up in a Parallels Desktop for Mac virtual machine may take a long time. (#PSBM-8528)

  • Using the WMI console is not supported in Windows virtual machines that you enter with the 'prlctl enter' command. For more information on how to work around the problem, see /en/114766. (#PSBM-9811)

  • A Linux virtual machine with less than 4 GB of RAM may hang on startup. To work around the problem, use the 'iommu=soft' option when booting the virtual machine. For details, see /en/114764. (#PSBM-11807)

  • Creating snapshots of a Container that has at least one 'prlctl enter' or 'prlctl exec' session open is not supported. To make a snapshot, close the open sessions first. (#PSBM-11871)

  • Xen virtual machines cannot be migrated to Virtuozzo virtual machines. (#PSBM-12122)

  • Virtuozzo may freeze a Container trying to consume more disk space than you allocated to it. To solve the problem, increase the amount of disk space for the affected Container. (#PSBM-12213)

  • The Bash 'echo' command does not report an error when trying to write to a file located on a Virtuozzo Storage cluster, even if the cluster does not have enough free space. (#PSBM-12621)

  • Soft lockups in the Linux kernel, up to version 2.6.37, may occur on stopping virtual machines. For more information, see /en/114761. (#PSBM-13963)

  • Traffic shaping may not work for bridged virtual network adapters on physical servers with Open vSwitch enabled. (#PSBM-14260)

  • It is impossible to use the iptables functionality on physical servers with Open vSwitch bridges enabled. (#PSBM-14334)

  • On systems upgraded from Virtuozzo hypervisor 4 to Virtuozzo 6.0, 'prlctl list –a' may not show the IP addresses of container-bridged network adapters. To view such IP addresses, use the 'vzlist –o IP' command. (#PSBM-14528)

  • Running virtual machines with Windows Server 2012 and Windows 8 is supported only on servers that have CPUs with the NX (No-eXecute) feature enabled. For details, see /en/114760. (#PSBM-14837)

  • Backing up a virtual machine with large virtual disks stored on an LVM partition may take a long time. (#PSBM-14971)

  • Running the Iometer tool in a virtual machine with Windows and a small amount of RAM may cause the virtual machine to crash. To work around the problem, increase the amount of RAM or swap allocated to the virtual machine. (#PSBM-15403)

  • The ebtables rules are flushed after restarting the ebtables service. (#PSBM-15641)

  • Creating a cache with updates may fail for containers that run Red Hat Enterprise Linux 5. (#PSBM-15707)

  • Cannot migrate a Container with over 2TB of data to a virtual machine. (#PSBM-21613)

  • On 32-bit Linux guest operating systems, the maximum size of a virtual hard disk was limited to 17592186040320 bytes (16 TiB - 4 KiB). (#PSBM-22193)

  • Migration of physical Linux hosts which use EFI and GPT to virtual machines is not supported. (#PSBM-24118)

  • Cannot resize plain virtual hard disks with the --resize_partition option. (#PSBM-26377)

  • Cannot migrate Virtuozzo Containers for Windows 4.5 hardware nodes to virtual machines. (#PSBM-29576)

  • The 'vzctl' utility does not recognize backups attached to virtual machines or Containers. (#PSBM-29752)

  • Virtual machine configurations with both EFI firmware and SCSI BusLogic controllers enabled are not supported. (#PSBM-30537)

  • Ubuntu 15.04 systemd immediately unmounts manually mounted directories (for more details, see As a workaround, you can downgrade the systemd package or rebuild it with the available patch. (#PSBM-33492, #PSBM-33498)

5. Deprecated Features

Features considered deprecated will be removed in the next major release of Virtuozzo. They will, however, work and remain supported in Virtuozzo 6.0. The following features are deprecated:

  • The Virtuozzo file system (VZFS). For more information, see /119015.

  • Migration of physical servers to Containers and migration of Xen virtual machines to virtual machines. For more information, see /119016.

  • The 'vzbackup', 'vzabackup', and 'pbackup' utilities. For more information, see /119017.

  • The global iptables mask configured in '/etc/sysconfig/vz'.

  • All UBC resources except 'physpages' and 'swappages'.

  • The 'vziptables' parameter configured in the kickstart file used for unattended installations of Virtuozzo.

  • VA Agent (Parallels Virtualization SDK will be used instead).

All Virtuozzo 6.0 users are advised to update their tools packages.

6. Obtaining the Update

You can download and install the update using the yum utility included in the Virtuozzo (formerly Parallels Cloud Server) 6.0 distribution.

Copyright (c) 1999-2015 Parallels IP Holdings GmbH and its affiliates. All rights reserved.

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