XenServer Release Notes
Release 4.1.0
Table of Contents
This document lists known issues in the current release of XenServer™. Where possible, workarounds are described.
Release Notes specific to the supported Windows Virtual Machines are present in the "Installing Windows VMs" chapter of the XenServer Virtual Machines Installation Guide. Release Notes specific to the supported Linux Virtual Machines are present in the "Installing Windows VMs" chapter of the same document.
For the latest up-to-date version of the XenServer release notes, visit the XenServer v4 Documentation page.
For further product usage information, or to find how you should report problems, visit the Citrix Support page.
System requirements, preparation, installation, and initial configuration are described in the Getting Started With XenServer document.
This release of the XenServer product family contains the following new features:
- Increased number of parallel running VMs
- Enhanced NPT support
- VLAN support in Standard Edition
- Improved Citrix Presentation Server performance and maximum number of user sessions.
- Host NIC bonding for fail-over (via CLI only)
- Centralized logging
- Management of network management interfaces via the CLI
- Initial shared fibre channel storage support (via CLI only)
- Enhanced support for NetApp filers, including snapshot and cloning
- Windows guest Hot disk remove
- ISCSI improvements
- Support for hot-plugging USB storage as a storage repository
- Rolling pool upgrade support
- NIC driver updates (e1000, BNX2, TG3), and support for 10Gb NICs from Mellanox and Chelsio
- Improved hardware support
- Oracle Enterprise Linux 5 x86 and x64 support
- Red Hat Enterprise Linux 5 x86 and CentOS 5 x64 guest support
- Windows Vista x86 guest support
- Red Hat Enterprise Linux, Oracle Enterprise Linux and CentOS installation from physical CD
- Java bindings
- Simulator for emulating resource pools without requiring multiple physical hosts
The XenCenter Windows management interface also has the following new features, in addition to being backwards compatible with older v4.0.1 XenServer hosts.
- Network Appliance storage repository creation
- iSCSI IQN scanning
- CIFS and NFS storage repository validity checking
- Storage repository repair and re-plugging.
- Default SR configuration and display
- Rolling upgrades from v4.0.1 to 4.1.0
- Pool hot-fix application
- Maintenance mode for hosts to facilitate upgrades
- Pool-wide server status report collation for submitting issue reports
- Warnings when VM performance is under threat
- Warnings when iSCSI host IQNs are duplicated across the pool
- Better display when XenServer Tools are not installed
- Linux-pack integration
- Automatic switching to RDP
- RDP sound configuration
- Configurable VNC keystrokes (to avoid conflict on international keyboards)
- Cut-and-paste to-and-from Windows VMs
- Undocked console menu for VM operations
This section details known issues with this beta release, and any workarounds which can be applied. Please report any other issues via your Citrix support representative.
CA-933: On machines with multiple disks, the XenServer boot loader is only written to the disk selected for installation.
For example, if you set the boot drive to the first disk, and then install XenServer Host on the second drive, and then subsequently change the system BIOS to assign the second drive to be the boot drive, it will fail to boot and properly renumber the disks. Installation to the second disk only works if the first disk has a boot loader already present which lets you boot off second disk, or if the BIOS permits you to boot directly off the second disk. Renumbering disks post-installation will not work. The only workaround is to manually edit menu.lst .
CA-4575, CA-5311: On servers with the ICH8 South Bridge chipset, XenServer might not detect the drive at installation due to a problem with the ata_piix driver. If you have this problem, set the machine's ATA/IDE mode in the Advanced section of the BIOS to use the Advanced Host Controller Interface (AHCI). This is usually set to off (legacy mode) by default. You might need to set the mode to "Native" to then access further SATA configuration options that allow selecting between AHCI, IDE, or RAID. It might also be available via Advanced->Drive Configuration->Disable Intel® RAID Technology and then Enable SATA AHCI mode. The Dell SAS 5/iR Controller in Dell 490 hosts exhibits this issue.
For more information, see http://www.intel.com/support/chipsets/imst/sb/cs-015988.htm.
CA-8767: Motherboards using the Intel 965 chipset with more than 2GB of memory may fail to boot successfully. This has been identified as a BIOS firmware issue, and appears to happen on any 64-bit operating systems (see Red Hat and Microsoft related bugs). To workaround this, downgrade your BIOS to version 1669, available from the Intel website.
CA-15337: When doing an upgrade or restoring from an upgrade, users should ensure that removable storage not in use by the XenServer installation is removed, in particular USB flash and hard drives. In particular, remote management tools like HP iLO or Dell RDAC may also cause a virtual USB device to appear in the host, so be sure to disable this functionality before upgrading your server.
CA-4065: When installing a Windows VM, if you leave the installer sitting at the first couple of prompt screens, the CPU usage on the XenServer Host (and on the VM) spikes to 100%. While this is going on, performance of other guests on the system may be reduced.
As soon as you press a key to respond to these prompts, everything behaves normally again. This only occurs during the early part of Windows installation and does not affect normal operation.
CA-10849. Multi-VCPU Vista 32-bit VMs may occasionally exhibit sluggish behavior after being resumed from a suspended state. To resolve this, reboot the VM and performance will return to normal.
CA-14448. If you are using Daemon Tools virtual CD/DVD-ROM emulator to use ISOs as if they were CDs in a Windows VM, you might get a blue screen of death when you try to defragment virtual disks larger than 128GB.
CA-15330. Microsoft Vista recommends a root disk of size 18GB or higher. The default size when installing this template is 16GB, which is 3GB greater than the minimum. However, users should consider increasing this to comply with the Microsoft recommendations when they install Vista VMs.
CA-15280. Users should refer to the Administrator Guide when making use of disk QoS settings within XenCenter for information on how these apply to different storage types. Not all storage types fully support setting QoS.
CA-5785: The Acronis Rescue CD does not work in a VM. It uses CPU features that Xen does not yet support. A future release of Acronis will support Xen; please contact the vendor for details.
CA-6966: When using NFS ISO storage repositories, a hard mount is used to communicate with the server. This means that the control domain can hang if the remote NFS server becomes unreachable. The workaround is to use CIFS-based mounts instead.
CA-9208: Citrix has seen data corruption issues using the iSCSI target provided by Adaptec SnapServers. This appears to be a problem with the SnapServer iSCSI implementation, and has been reproduced by Adaptec using a standard (non-XenServer) Linux distribution. We are currently working with Adaptec to find a solution to this problem. Until this issue is resolved, XenServer users are strongly encouraged to use NFS rather than iSCSI storage repositories when using SnapServer products. In general, when using network-based storage hardware, users should ensure the software and/or firmware on the devices being used is up to date, as recommended by the manufacturer.
CA-9772. The Windows PV drivers do not send a gratuitous ARP after live relocation if the guest has previously been hibernated. Note that hibernation is not a supported use-case, since direct suspension of a VM is supported instead.
CA-12866: Users should avoid attaching read-only VDIs to Windows VMs as this may result in unexpected behaviour and instability of the virtual machine. This includes NetApp snapshot VDIs; users wishing to attach a snapshot VDI to a Windows VM should first make a read-write copy of the snapshot using the vdi-copy CLI command
CA-13972: For XenServer 4.0, users were able to edit networking configuration files directly, and use the service network restart command to reconfigure networking on a host. This should not be done in XenServer 4.1 as the XenAPI has been extended to cover remote networking configuration. Please refer to the Administrator's Guide for details on how to setup networking using the CLI.
CA-14197: When upgrading a pool or server, users should not leave VMs suspended across the upgrade. Importantly, any suspended virtual machine with a CD drive attached (with the Tools ISO or a local physical drive, for example) will not be resumable after upgrade. To get the virtual machine back into a usable state, one would have to perform a "Force Shutdown" of the suspended VM.
This section describes some of the more detailed changes from v4.0.1 to v4.1.0, categorized by the broad area in which the change was made.
- Extend iSCSI backend to enable scanning of valid IQN entries advertised by the iSCSI target.
- The td-util command in the control domain has been extended to include a "read" option for analyzing VHD files.
- Disabled multipath support in the QLogic kernel module, in favor of using other failover mechanisms.
- The Storage Manager plugins and Windows PV drivers now support pass through of SCSI inquiry data.
- The bundled version of OpeniSCSI tools has been upgraded to version 2.0-865.13. This version contains a number of upstream bug-fixes, notably when connecting to Hitachi SAN storage.
- Added support for shared, HBA-attached SRs to enable FC support.
- USB storage devices and CD devices can now be hot plugged into the host, and will be automatically added as VDIs within a storage repository (SR) of type "udev" on the host or pool.
- Storage Manager plugin has been added for Network Appliance filers, including support for fast snapshot and cloning.
- Scanning for files within a ISO SR is now case-independent.
- The
vm-uuidparameter can now be passed to SR plugins when creating VDIs, allowing the plugins to determine the SR to be used for crash dump and suspend images on a per-VM basis. - The Storage Manager API has been rationalized to use XML-RPC for communication between the storage backends and the control domain.
- Modify system logger scripts to support remote logging configuration via the XenAPI.
- In order to reduce writes to disk XenAPI tasks and sessions are no longer persistent. Tasks running when restarting a host or restarting the xapi service will no longer be listed listed by the xe task-list command.
- The detection heuristics performed by a member host to detect that its master host has disappeared have been improved. This information is used by member hosts to enter emergency mode and wait for a new master host to appear in the resource pool.
- Make guest domain tear-down restartable, to avoid the control domain becoming unresponsive when shutting down very large guests (e.g. 32GB).
- The console emulator for guests now only binds to the localhost interface rather than all interfaces.
- Support for processors with Nested Page Tables (NPT) , such as recent AMD Barcelona chips, has been improved.
- The Intel hardware random number generator module has been disabled since it can deadlock during boot on a multi-processor machine, resulting in an occasional hang when booting XenServer on some hardware.
- The IPv6 module has been disabled by default in the control domain to prevent link local addresses from being assigned to bridges without explicit user action.
XenAPI.pyhas been moved to/usr/lib/python2.4/site-packagesto allow easy consumption by API clients running in the control domain.- A security issue has been fixed in the parsing of
grub.conffiles which could permit arbitrary command execution in the control domain if starting an untrusted Linux guest (CVE-2007-4993). - The number of backend devices in the control domain has been increased from 250 to 760 to improve the supported number of parallel running VMs.
- QEMU security has been hardened by making it drop root privileges once an HVM domain is started and restricting its access to xenstore to those of the guest VM.
- Various network driver updates to Intel Gigabit, BNX2, and TG3 cards.
- Added XAPI_DOM0_MEM_BASE parameter to /etc/sysconfig/xapi configuration file, which can control the base amount of dom0 memory allocated as well.
- The hotfix format has been improved to include whether or not the host or guests need to be restarted, a description of what to do after applying the patch, and a UUID to uniquely identify the hotfix.
- A xe-xentrace script has been added to simplify the process of obtaining trace results while debugging performance issues with Windows VMs.
- The command "service firstboot status" will now show the state of the firstboot scripts: which have run and succeeded, failed, or are new.
- Firstboot scripts can now be added to
/etc/firstboot.d. State will be stored in/etc/firstboot.d/state, logs in/etc/firstboot.d/log, and configuration files consumed by firstboot scripts should be in/etc/firstboot.d/data. - Support Dell MD3000 RDAC multipath storage is now supported.
- Modify NFS client to support mixed mount options for multiple mounts pointing to the same export, but on different sub-directories.
- Scheduling of virtual CPUs from the same domain onto the same physical processor is now avoided to improve performance of multi-vCPU Windows guests.
- Modify networking scripts to be written out by the host agent, to support API-level network management of physical NICs.
- The xen-bugtool command now supports an option to output files in zip format to make them easier to work with on Windows, as well as being extended with personal privacy options to control the information captured.
- The bundled version of sqlite has been upgraded to 3.5.1-1 to solve some rare corruption issues when accessed by multiple readers. This is only an issue when the database is directly accessed by unsupported third-party clients, which is definitely not recommended in any situation.
- A
xenstore_datafield has been added to the VM table, which can be used by third-parties to store data in the xenstore/local/domain/{domid}/vm-datanamespace at VM creation time. - The Broadcom NetXtreme II (BNX2) driver has been updated to version 1.6 to improve compatibility with modern hardware.
- Added support for 10Gb Ethernet cards from Mellanox and Chelsio. Also improved gigabit support for a range of cards.
- The control domain kernel has been upgraded to upstream 2.6.18-53.el5, with our custom patches maintained.
- The control domain user-space binaries have been updated to CentOS 5.1 where applicable.
- A xe-edit-bootloader helper script has been added to allow editing the bootloader configuration of a Linux VM that cannot be booted due to an incorrect
grub.conf. - VM.actions_after_reboot and VM.actions_after_shutdown parameters have been added. Details about the last shutdown are now recorded and stored in the VM's
other_configdictionary. - A Host.restart_agent API call has been added to allow restarting the xapi service.
- PIF.plug and PIF.unplug API calls have been added to allow fine-grained control over usage of PIF objects with network objects.
- In previous releases the separator - (dash) was used in specifying map parameters with the xe CLI. This syntax still works but is deprecated. The preferred syntax is to use a : (colon). For example:
xe vm-param-set uuid=
VM uuidother-config:foo=baa - Removed the xe.exe Windows CLI from the main install ISO , since it is now included as part of the XenCenter installation MSI . The xvaverify.exe tool is also included in the XenCenter installation now.
- The xe pool-sync-database CLI command can be used to explicitly synchronize the pool database across all member hosts immediately.
- A xe pool-designate-new-master CLI command has been added which performs an orderly handover of the role of master host to another host in the resource pool. This command only works when the current master is online and is not a replacement for the emergency-mode commands.
- A xe vm-compute-maximum-memory CLI command has been added which computes the amount of maximum guest memory for a given amount of host physical RAM.
- Numeric return values from CLI commands are no longer sometimes displayed in scientific format.
- A new xe host-evacuate CLI command has been added which disables the host and attempts to migrate virtual machines to other hosts in the resource pool. This command is intended to prepare a host for upgrading or maintenance.
- Added a mapping between hosts and patches with a
hostsfield in xe patch-list and a "patch" field in xe host-list. - The xe patch-upload CLI command now returns the UUID of the uploaded patch to simplify automated hot-fixing via scripting.
- A xe vdi-introduce CLI command has been added which creates a VDI object and verifies the existence of the disk by calling the corresponding storage plugin "vdi_update" call. If the "vdi_update" fails then the VDI object is deleted.
- A xe host-management-disable CLI command has been added which disables listening on an external management interface and disconnects all connected XenCenter GUIs.
- A xe vdi-forget CLI command has been added which unconditionally removes a VDI record from the database without affecting the storage backend.
- A xe sr-probe CLI command has been added which performs a backend-specific scan using the supplied
device_configparameter. If thedevice_configparameter is complete the command will return a list of the SRs present of this type on the device, if any. If thedevice_configparameter is partial a backend-specific scan will be performed, and results will be returned as backend-specific XML to guide the user in improving thedevice_configparameter. - New CLI command xe host-management-reconfigure to reconfigure the management interface. When given the UUID of a PIF object the server will determine which IP address to rebind to itself, but it must not be in emergency mode for this to work.
- A xe bond-create command has been added which creates a network bond interface from the supplied PIF UUIDs . The command will fail if any of the supplied PIFs are in another bond already, has a VLAN tag set, are not on the same host, or fewer than two PIFs are specified.
- Add a CLI command xe vm-shadow-memory-set which can control the amount of overhead memory granted to HVM guests. Also add a Citrix Presentation Server application template which has an optimal value.
- A xe host-syslog-reconfigure CLI command has been added to control system logging configuration as set in the host logging parameter.
- The XenServer 3.2 compatibility mode is no longer supported.
- The xe sr-list CLI command now includes the host to which the SR is attached, or "shared" if it is shared across a pool. Local storage SRs are now named "Local storage" instead of "Local storage on <hostname>".
- A xe vm-memory-shadow-multiplier-set has been added to allow configuration of the shadow memory multiplier which can increase performance of applications such as Citrix Presentation Server. The default multiplier is 1.0 for all templates except the Citrix Presentation Server one, which is higher.
- The XenServer 3.2 ("Geneva") compatibility mode is no longer supported.
- A xe patch-destroy CLI command has been added which allows deletion of patches that have been uploaded but not applied.
- A xe template-export CLI command has been added which allows export of VM templates in a similar fashion to VMs, which had previously only been possible via XenCenter. Exported templates can be imported using the xe vm-import command or via XenCenter.
- CLI error messages are now printed on stderr instead of stdout.
- A
other-configparameter has been added to the PIF and VIF objects to support various low-level networking configuration options. - The xe pif-reconfigure-ip CLI command now validates the arguments passed to it.
- The xe event-wait command supports extra syntax enabling the command to block until a field takes a different value, instead of the field taking a specific value.
x=ymeans "wait for field x to take value y" whilex=/=ymeans "wait for field x to take any value other than y". - If the parameter "metadata=true" is passed to the xe vm-export CLI command, then only the VM metadata will be exported and not the disks themselves.
- Implement xe host-send-debug-keys to send hypervisor debug keys to hosts in a pool.
- New xe host-set-hostname-live CLI command to alter the hostname immediately without requiring a reboot.
- Added xe host-is-in-emergency-mode CLI command, to diagnose if a host is in emergency mode.
- The timeout for the pool master to receive heartbeat messages from pool members has been increased to 200 seconds from the original value of 30 seconds.
- Support exporting VMs with individual disks greater than 132GiB.
- VMs may be imported and exported while suspended.
- Improve the reboot delay algorithm to only penalize guests which reboot repeatedly in a loop, and not for guests which perform a very fast restart a single time.
- Added driver for Solarflare Solarstorm SFC4000 10G Ethernet controller.
- Significantly improve the performance of the control stack when running a large number of concurrent VMs in a resource pool.
- Added Xen support for booting recent Linux kernels (2.6.23+) which use the paravirt ops interface. There are no officially supported distributions which use this kernel yet.
- Added a Red Hat Enterprise Linux 5 and CentOS 5 64-bit kernel to the
xs-tools.iso, with fixes for various Xen-related bugs bundled with the vendor kernels. - Added support for Red Hat Enterprise Linux 5.0 ×64, and CentOS 5.0 ×64 via two new built-in templates.
- Add support for Windows Vista 32-bit via a new built-in template, which is a normal Windows template with a bigger root disk of 16GB, and the NX platform bit turned on.
- Add hot disk-remove support to the Windows para-virtual drivers.
- Update Red Hat 4 and 5, and CentOS 4 and 5 vendor kernels with latest upstream security fixes.
- A XenServer-patched CentOS 5 kernel is now supplied on the
xs-tools.iso, with all the known Xen-related issues in the upstream kernel fixed. We recommend users upgrade from the upstream kernel to this version before reporting issues. - Visual corruption in the Linux para-virtual console emulation has been fixed, mostly seen when installing SUSE Enterprise Linux 10 guests.
- The
boot.inientry specific to the Windows PV drivers has been removed. A normal boot will use the PV drivers and a safe mode boot will use the slower emulated devices. - Debian guests will now correctly map their CD-ROMs to the
/dev/cdromdevice, rather than just to/dev/xvdd. - One of the console entries when installing guest tools on SUSE Enterprise Linux 10 has been removed to address an issue with console lockups.
- Fix Windows para-virtual drivers to handle the case where Windows turns TCP RX checksums on and UDP RX off. This manifests when a Linux VM is serving up DNS queries on the same host as a Windows DNS client.
- Support RedHat Enterprise Linux 5 and CentOS 5 32-bit guest installation directly from a CD image or physical CD drive.
- Improve Windows para-virtual drivers tolerance to very slow backend disk devices (e.g. overloaded NFS filers)
- Updated Red Hat Enterprise Linux 4 kernel to 2.6.9-67.0.4EL.
- Updated control domain and Red Hat Enterprise Linux 5 kernel to 2.6.18-53.1.6.el5.
- Linux text console emulation is improved when going through shell history.
- Support booting Linux kernels on disks where the start of the
ext2/3boot partition is past the 4GB offset on a disk. - Domain 0 and Red Hat 5 vendor kernels are now based on 2.6.18-53.1.13.el5.
- Support PXE responses with multiple servers when booting HVM guests.
- The API documentation now mentions whether a field or message is deprecated or not; entities marked as deprecated will be phased out of future releases.
- Java bindings have been added, along with example code and Javadoc-based documentation.
- A Xen simulator has been added, suitable for emulating resource pools without requiring multiple physical hosts.
- Modify the CD ISOLINUX boot-loader configuration to add
"vga=keep"in safe mode to aid debugging, and remove some redundant options. - Added
extlinuxas an alternative boot-loader to alleviate problems booting with some SAN configurations. Available only as an answerfile option. - Network-based installations will now succeed on non-A/B/C class static IP configurations.
- Any errors encountered obtaining an IP address via DHCP are now displayed prior to prompting for a network package location URL.
- Hostnames are now validated to ensure they only contain valid characters.
- Host installation now defaults to 'Verify media' for additional CD media.
- When specifying a static IP configuration a DNS server can now be specified to allow name resolution for package location URLs.
- Hostname and password settings are now preserved during an upgrade.
- Management network configuration is now preserved during an upgrade.
- Any networking configuration specified to access the package location URL during installation is now retained and offered as the default networking configuration for the host.
- Host names can now be specified as fully-qualified domain names (FQDNs).
- Use of extlinux rather than grub as the host’s bootloader can be specified by adding "bootloader=extlinux" to the kernel command line during host installation.
- The prompt for installation of the Linux pack can be suppressed by adding "onecd" to the kernel command line during host installation.
- Storage partitions are now catalogued using a descriptive symbolic link rather than the device name to avoid device renaming issues with hot-plugged and remote disks.
- The default iSCSI IQN for the host is now created correctly when hostname is configured statically.
- A user name and password can now be specified when accessing installation packages on password-protected FTP sites and HTTP servers using basic authentication.
- Static DNS servers specified during installation are now also used when configuring the management interface.
- The Linux P2V installer now names the new VM from the host-name, distribution name and version.
- During upgrade the host installer now preserves the management network configuration if requested and therefore no longer prompts the user to enter the information.
- The host installer now retains the host SSH keys when an upgrade is selected.
- Added file associations to automatically handle license files, VM exports, and hotfixes by launching XenCenter with the appropriate dialog.
- Splash screen to provide more feedback during XenCenter loading.
- Improved the license expiry warnings which periodically display when a host is less than a month away from expiry.
- A patch application wizard to make applying hotfixes to multiple pools significantly easier, and also display patch status of hosts in the General pane.
- iSCSI multi-homing support, using the iSCSI IDs and not LUN ids.
- Additional support for cancelling long-running tasks, such as storage actions.
- XenCenter includes new functionality to place servers in Maintenance Mode, migrating all the VMs off the server and disabling it. This feature is useful when hardware in the server needs to replaced or software updates need to be applied. If the pool master is placed in maintenance mode, a new server is elected as master.
- Support changing the password for a storage repository.
- XenCenter's Import VM wizard now has the ability to map a VM's virtual network interfaces to new networks, in the event that the VM is imported to a different pool, or the networks are no longer available since the VM was exported.
- Support exporting/importing VMs through a HTTP proxy.