How to Use host-cpu-tune to Fine tune XenServer 6.2.0 Performance

Pinning Strategies

  • No Pinning (default): When no pinning is in effect, the Xen hypervisor is free to schedule domain’s vCPUs on any pCPUs.
    • Pros: Greater flexibility and better overall utilization of available pCPUs.
    • Cons: Possible longer memory access times, particularly on NUMA-based hosts. Possible lower I/O throughput and control plane operations when pCPUs are overcommitted.
    • Explanation: When vCPUs are free to run on any pCPU, they may allocate memory in various regions of the host’s memory address space. At a later stage, a vCPU may run on a different NUMA node and require access to that previously allocated data. This makes poor utilization of pCPU caches and incur in higher access times to that data. Another aspect is the impact on I/O throughput and control plane operations. When more vCPUs are being executed than pCPUs that are available, the Xen hypervisor might not be able to schedule dom0’s vCPUs when they require execution time. This has a negative effect on all operations that depend on dom0, including I/O throughput and control plane operations.
  • Exclusive Pinning: When exclusive pinning is on effect, the Xen hypervisor pins dom0 vCPUs to pCPUs in a one-to-one mapping. That is, dom0 vCPU 0 runs on pCPU 0, dom0 vCPU 1 runs on pCPU 1 and so on. Any VM running on that host is pinned to the remaining set of pCPUs.
    • Pros: Possible shorter memory access times, particularly on NUMA-based hosts. Possible higher throughput and control plane operations when pCPUs are overcommitted.
    • Cons: Lower flexibility and possible poor utilization of available pCPUs.
    • Explanation: If exclusive pinning is on and VMs are running CPU-intensive applications, they might under-perform by not being able to run on pCPUs allocated to dom0 (even when dom0 is not actively using them).

Note: The exclusive pinning functionality provided by host-cpu-tune will honor specific VM vCPU affinity configured using the VM parameter vCPU-params:mask. For more information, refer to the VM Parameters section in the appendix of the XenServer 6.2.0 Administrator’s Guide.

Using host-cpu-tune

The tool can be found in /usr/lib/xen/bin/host-cpu-tune. When executed with no parameters, it displays help:

[root@host ~]# /usr/lib/xen/bin/host-cpu-tune

Usage: /usr/lib/xen/bin/host-cpu-tune { show | advise | set <dom0_vcpus> <pinning> [–force] }

show Shows current running configuration

advise Advise on a configuration for current host

set Set host’s configuration for next reboot

<dom0_vcpus> specifies how many vCPUs to give dom0

<pinning> specifies the host’s pinning strategy

allowed values are ‘nopin’ or ‘xpin’

[–force] forces xpin even if VMs conflict

Examples: /usr/lib/xen/bin/host-cpu-tune show

/usr/lib/xen/bin/host-cpu-tune advise

/usr/lib/xen/bin/host-cpu-tune set 4 nopin

/usr/lib/xen/bin/host-cpu-tune set 8 xpin

/usr/lib/xen/bin/host-cpu-tune set 8 xpin –force

[root@host ~]#

Recommendations

The total number of pCPUs and advise as follows:

# num of pCPUs < 4 ===> same num of vCPUs for dom0 and no pinning

# < 24 ===> 4 vCPUs for dom0 and no pinning

# < 32 ===> 6 vCPUs for dom0 and no pinning

# < 48 ===> 8 vCPUs for dom0 and no pinning

# >= 48 ===> 8 vCPUs for dom0 and excl pinning

The utility works in three distinct modes:

  1. Show: This mode displays the current dom0 vCPU count and infer the current pinning strategy.

    Note: This functionality will only examine the current state of the host. If configurations are changed (for example, with the set command) and the host has not yet been rebooted, the output may be inaccurate.

  2. Advise: This recommends a dom0 vCPU count and a pinning strategy for this host.

    Note: This functionality takes into account the number of pCPUs available in the host and makes a recommendation based on heuristics determined by Citrix. System administrators are encouraged to experiment with different settings and find the one that best suits their workloads.

  3. Set: This functionality changes the host configuration to the specified number of dom0 vCPUs and pinning strategy.

    Note: This functionality may change parameters in the host boot configuration files. It is highly recommended to reboot the host as soon as possible after using this command.

    Warning: Setting zero vCPUs to dom0 (with set 0 nopin) will cause the host not to boot.

Resetting to Default

The host-cpu-tune tool uses the same heuristics as the XenServer Installer to determine the number of dom0 vCPUs. The installer, however, never activates exclusive pinning because of race conditions with Rolling Pool Upgrades (RPUs). During RPU, VMs with manual pinning settings can fail to start if exclusive pinning is activated on a newly upgraded host.

To reset the dom0 vCPU pinning strategy to default:

  1. Run the following command to find out the number of recommended dom0 vCPUs:

    [root@host ~]# /usr/lib/xen/bin/host-cpu-tune advise

  2. Configure the host accordingly, without any pinning:
    • [root@host ~]# /usr/lib/xen/bin/host-cpu-tune set <count> nopin
    • Where <count> is the recommended number of dom0 vCPUs indicated by the advise command.
  3. Reboot the host. The host will now have the same settings as it did when XenServer 6.2.0 was installed.

Usage in XenServer Pools

Settings configured with this tool only affect a single host. If the intent is to configure an entire pool, this tool must be used on each host separately.

When one or more hosts in the pool are configured with exclusive pinning, migrating VMs between hosts may change the VM's pinning characteristics. For example, if a VM are manually pinned with the vCPU-params:mask parameter, migrating it to a host configured with exclusive pinning may fail. This could happen if one or more of that VM's vCPUs are pinned to a pCPU index exclusively allocated to dom0 on the destination host.

Additional commands to obtain information concerning CPU topology:

xenpm get-cpu-topology

xl vcpu-list

Related:

Driver Disk for Microsemi smartpqi 1.1.4-132 – For XenServer 7.X CR

Who Should Install this Driver Disk?

Customers running a Citrix XenServer Current Release 7.2 or later who use Microsemi’s smartpqi driver and wish to use the latest version of the following:

Driver Module Version
smartpqi 1.1.4-132

Issues Resolved In this Driver Disk

Includes general enhancements and bug fixes.

Firmware requirements for this Driver Disk

Please ensure that your hardware is running firmware versions greater or equal to the ones specified below, according to the chipset of your particular device:

  • Microsemi Adaptec SmartHBA 2100 Adapters with Firmware 1.60 [0]
  • Microsemi Adaptec SmartRAID 3100 Adapters with Firmware 1.60 [0]

Note: If your device has been branded by your OEM, please ensure that you consult them regarding the currently supported driver/firmware versions.

Installing the Driver Disk

Customers should use XenServer Command Line Interface (CLI) to install this update. Once the driver has been installed, the server must be restarted. As with any software update, Citrix advises customers to back up their data before applying this driver disk.

Please note that the attachment to this article is a zip file. It contains both the driver disk ISO mentioned below, and the source code for the driver. The zip file should be unzipped (to produce the driver disk ISO image), before carrying out the steps below. The source code file is not necessary for driver disk installation: it is provided to fulfill licensing obligations.

Installing as Part of a Clean XenServer Installation

  1. After you have selected your keyboard layout at the first installer prompt, you will be presented with a welcome screen. At this point, press F9 on your keyboard, and insert the CD with the driver disk in it, or use one of the other methods such as installation over the network.

    Note: If installation over HTTP or FTP is to be used, the ISO image must be unpacked at that location (i.e. the installer expects to find the contents of the ISO at that network location, not the ISO itself).

  2. The installer will proceed to attempt to load the driver. If this is successful, you can continue with the installation as normal. Near the end of the installation, you will be prompted to re-insert the driver disk (otherwise known as a XenServer supplemental pack) so that the driver can be installed onto disk. You must re-supply the driver disk at this point. Failure to do so will mean that the installation will not contain the new drivers. After this step, no further action is required.

If the installer fails to load the new driver from the driver disk, it is likely to be because an earlier version of the driver has already been loaded. In general, this is because a hardware component is present that is supported by the version of the driver that ships as part of XenServer (even if another component is present that requires a newer version of the driver). To avoid the existing driver being loaded, use the following procedure.

  1. Reboot the host, leaving the XenServer installation CD-ROM in the drive.
  2. At the boot: prompt, type:

    shell

  3. You will now be presented with a command prompt. Type the following:

    rmmod smartpqi

    If this succeeds (i.e. there are no error messages printed), the installer’s versions of the drivers have been unloaded. If error messages are presented, it is likely that other drivers depend on one or more of the drivers you are attempting to unload. If this is the case, please contact Citrix Technical Support.

  4. Type

    exit

    or press Control+D on your keyboard, to return to the installer.

  5. Use the procedure described above to provide the driver disk to the installer, which should now load correctly.

Installing the Update by using the xe Command Line Interface

Perform the following steps to install the update remotely using the xe CLI:

  1. Download the update to a known location on a computer that has XenCenter installed.
  2. Upload the update:

    xe update-upload file-name=driver-microsemi-smartpqi-1.1.4_132.iso

    Note: The UUID of the update is returned when the upload completes.

  3. Apply the update:

    xe update-apply uuid=ed6639fb-a291-408b-bca9-6652e7c4266c

  4. To complete the installation, restart the host. This ensures that the driver loads correctly.

Files

Update Files

Component Details
Filename driver-microsemi-smartpqi-1.1.4_132.iso
File sha256 62a9bc058fe9ea441e61a803506cadd7ed3d72d778526596ac2368c82f463693
Source Filename driver-microsemi-smartpqi-1.1.4_132-sources.iso
Source File sha256 9bbaea0095e8b17853350072881a1265b103ccd8c342672b127d6304ac63a77f
Zip Filename driver-microsemi-smartpqi-1.1.4_132.zip
Zip File sha256 7b4e31cafea8797551a40cfc9b79aeb7a849a80b343991f6912c9cb8cedfc014
Size of the Zip file 135.22 MB

RPMs Provided

RPM Name
microsemi-smartpqi-1.1.4_132-1.x86_64.rpm

More Information

If you experience any difficulties, contact Citrix Technical Support.

For information on how to build driver disks, refer to Citrix XenServer ® Supplemental Packs and the DDK Guide .

Related:

  • No Related Posts

Driver Disk for Microsemi smartpqi 1.1.2-125 – For XenServer 7.x CR

Who Should Install this Driver Disk?

Customers running a Citrix XenServer 7.x Current Release who use Microsemi’s smartpqi driver and wish to use the latest version of the following:

Driver Module Version
smartpqi
1.1.2-125

Issues Resolved In this Driver Disk

Includes general enhancements and bug fixes.

Firmware requirements for this Driver Disk

Please ensure that your hardware is running firmware versions greater or equal to the ones specified below, according to the chipset of your particular device:

  • Microsemi Adaptec SmartRAID 3100 Adapters with Firmware 1.32 [0]
  • Microsemi Adaptec SmartHBA 2100 Adapters with Firmware 1.32 [0]

Note: If your device has been branded by your OEM, please ensure that you consult them regarding the currently supported driver/firmware versions.

Installing the Driver Disk

Customers should use XenServer Command Line Interface (CLI) to install this update. Once the driver has been installed, the server must be restarted. As with any software update, Citrix advises customers to back up their data before applying this driver disk.

Please note that the attachment to this article is a zip file. It contains both the driver disk ISO mentioned below, and the source code for the driver. The zip file should be unzipped (to produce the driver disk ISO image), before carrying out the steps below. The source code ISO is not necessary for driver disk installation: it is provided to fulfill licensing obligations.

Installing as Part of a Clean XenServer Installation

  1. Once you have selected your keyboard layout at the first installer prompt, you will be presented with a welcome screen. At this point, press F9 on your keyboard, and insert the CD with the driver disk in it, or use one of the other methods such as installation over the network.

    Users should note that if installation over HTTP or FTP is to be used, the ISO image must be unpacked at that location (i.e. the installer expects to find the contents of the ISO at that network location, not the ISO itself).

  2. The installer will proceed to attempt to load the driver. If this is successful, you can continue with the installation as normal. Near the end of the installation, you will be prompted to re-insert the driver disk (otherwise known as a XenServer supplemental pack) so that the driver can be installed onto disk. You must re-supply the driver disk at this point. Failure to do so will mean that the installation will not contain the new drivers. After this step, no further action is required.

If the installer fails to load the new driver from the driver disk, it is likely to be because an earlier version of the driver has already been loaded. In general, this is because a hardware component is present that is supported by the version of the driver that ships as part of XenServer (even if another component is present that requires a newer version of the driver). To avoid the existing driver being loaded, use the following procedure.

  1. Reboot the host, leaving the XenServer installation CD-ROM in the drive.
  2. At the boot: prompt, type:

    shell

  3. You will now be presented with a command prompt. Type the following:

    rmmod smartpqi

    If this succeeds (i.e. there are no error messages printed), the installer’s versions of the drivers have been unloaded. If error messages are presented, it is likely that other drivers depend on one or more of the drivers you are attempting to unload. If this is the case, please contact Citrix Technical Support.

  4. Type

    exit

    or press Control+D on your keyboard, to return to the installer.

  5. Use the procedure described above to provide the driver disk to the installer, which should now load correctly.

Installing the Update by using the xe Command Line Interface

Perform the following steps to install the update remotely using the xe CLI:

  1. Download the update to a known location on a computer that has XenCenter installed.
  2. Upload the update:

    xe update-upload file-name=driver-microsemi-smartpqi-1.1.2_125.iso

    Note: The UUID of the update is returned when the upload completes.

  3. Apply the update:

    xe update-apply uuid=119da241-7a63-42f1-852e-803a7fa5bbdb

  4. To complete the installation, restart the host. This ensures that the driver loads correctly.

Files

Update Files

Component Details
Filename driver-microsemi-smartpqi-1.1.2_125.iso
File sha256 4ff3a0f63c1042a508c4f747b853d9ce1437d5ca380de1641e42b83bfac284e1
Source Filename driver-microsemi-smartpqi-1.1.2_125-sources.iso
Source File sha256 0e9a02a23b5416ce8631dfd405b64a985c616d43dad07e6be21c8867196bc4a3
Zip Filename driver-microsemi-smartpqi-1.1.2_125.zip
Zip File sha256 079a37b5fcfbf28a74b8484fc18407142b445ef38d34ff77bdaa515932fca472
Size of the Zip file 0.12 MB

RPMs Provided

RPM Name
microsemi-smartpqi-1.1.2_125-1.x86_64.rpm

More Information

If you experience any difficulties, contact Citrix Technical Support.

For information on how to build driver disks, refer to Citrix XenServer ® 7.2 Supplemental Packs and the DDK Guide.

Related:

  • No Related Posts

Driver Disk for Microsemi aacraid – 1.2.1.56008 – For XenServer 7.x CR

Who Should Install this Driver Disk?

Customers running a Citrix XenServer Current Release 7.2 or later who use Microsemi’s aacraid driver and wish to use the latest version of the following:

Driver Module Version
aacraid 1.2.1.56008

Issues Resolved In this Driver Disk

Includes general enhancements and bug fixes.

Firmware requirements for this Driver Disk

Please ensure that your hardware is running firmware versions greater or equal to the ones specified below, according to the chipset of your particular device:

  • Microsemi Adaptec HBA 1000 Series Host Bus Adapters with Firmware 4.02 [0]
  • Adaptec RAID 8805 with Firmware 33263

Note: If your device has been branded by your OEM, please ensure that you consult them regarding the currently supported driver/firmware versions.

Installing the Driver Disk

Customers should use XenServer Command Line Interface (CLI) to install this update. Once the driver has been installed, the server must be restarted. As with any software update, Citrix advises customers to back up their data before applying this driver disk.

Please note that the attachment to this article is a zip file. It contains both the driver disk ISO mentioned below, and the source code for the driver. The zip file should be unzipped (to produce the driver disk ISO image), before carrying out the steps below. The source code file is not necessary for driver disk installation: it is provided to fulfill licensing obligations.

Installing as Part of a Clean XenServer Installation

  1. After you have selected your keyboard layout at the first installer prompt, you will be presented with a welcome screen. At this point, press F9 on your keyboard, and insert the CD with the driver disk in it, or use one of the other methods such as installation over the network.

    Note: If installation over HTTP or FTP is to be used, the ISO image must be unpacked at that location (i.e. the installer expects to find the contents of the ISO at that network location, not the ISO itself).

  2. The installer will proceed to attempt to load the driver. If this is successful, you can continue with the installation as normal. Near the end of the installation, you will be prompted to re-insert the driver disk (otherwise known as a XenServer supplemental pack) so that the driver can be installed onto disk. You must re-supply the driver disk at this point. Failure to do so will mean that the installation will not contain the new drivers. After this step, no further action is required.

If the installer fails to load the new driver from the driver disk, it is likely to be because an earlier version of the driver has already been loaded. In general, this is because a hardware component is present that is supported by the version of the driver that ships as part of XenServer (even if another component is present that requires a newer version of the driver). To avoid the existing driver being loaded, use the following procedure.

  1. Reboot the host, leaving the XenServer installation CD-ROM in the drive.
  2. At the boot: prompt, type:

    shell

  3. You will now be presented with a command prompt. Type the following:

    rmmod aacraid

    If this succeeds (i.e. there are no error messages printed), the installer’s versions of the drivers have been unloaded. If error messages are presented, it is likely that other drivers depend on one or more of the drivers you are attempting to unload. If this is the case, please contact Citrix Technical Support.

  4. Type

    exit

    or press Control+D on your keyboard, to return to the installer.

  5. Use the procedure described above to provide the driver disk to the installer, which should now load correctly.

Installing the Update by using the xe Command Line Interface

Perform the following steps to install the update remotely using the xe CLI:

  1. Download the update to a known location on a computer that has XenCenter installed.
  2. Upload the update:

    xe update-upload file-name=driver-microsemi-aacraid-1.2.1.56008.iso

    Note: The UUID of the update is returned when the upload completes.

  3. Apply the update:

    xe update-apply uuid=fb34e49f-c66c-453f-9128-7c2f8f3eb93f

  4. To complete the installation, restart the host. This ensures that the driver loads correctly.

Files

Update Files

Component Details
Filename driver-microsemi-aacraid-1.2.1.56008.iso
File sha256 17fd3d6bf413816771dab0f230eb172aa3d5623d1b004978a6ce54e95fcd086b
Source Filename driver-microsemi-aacraid-1.2.1.56008-sources.iso
Source File sha256 3c540b1da6558d5a3850c5a66469bb07f4dfe47d4a012e50f1621c074cacb70b
Zip Filename driver-microsemi-aacraid-1.2.1.56008.zip
Zip File sha256 0160e4ebc28c5f71a85104d92b37cc27e361e3219ec730a42069d19096335c83
Size of the Zip file 135.48 MB

RPMs Provided

RPM Name
microsemi-aacraid-1.2.1.56008-2.x86_64.rpm

More Information

If you experience any difficulties, contact Citrix Technical Support.

For information on how to build driver disks, refer to Citrix XenServer Supplemental Packs and the DDK Guide .

Related:

  • No Related Posts

7022546: Updating microcode in Xen environments.

SLES12SP2 and newer Xen environments:

Beginning withSLES12SP2, Dom0 is now a PVOPS based kernel (kernel-default), whichhas no interface for microcode updates while running as a Dom0.However, if the initrd contains an updated microcode, and Xen is madeaware of its existence, the update will be applied during the Xenearly boot process. Updates using this method required a host rebootafter correctly adding the microcode to the initrd.

Installing a microcode update in SLES12SP2 and newerenvironments:

1. Determine current microcode level:

# grep -m1 microcode/proc/cpuinfo

microcode : 0x2000011

2. Install updated microcode package (ucode-intel, or ucode-amd).

3. Rebuild initrd using `mkinitrd`.

NOTE – The `lsinitrd` command can beused to verify the microcode is correctly inserted into the initrd.

#lsinitrd /boot/initrd-4.12.14-23-default

Image:/boot/initrd-4.12.14-23-default:11M

================================================================

EarlyCPIOimage

================================================================

drwxr-xr-x 1 root root 0 Jul 13 13:05 .

-rw-r–r– 1root root 2 Jul 13 13:05 early_cpio

drwxr-xr-x 1 root root 0 Jul 13 13:05 kernel

drwxr-xr-x 1root root 0 Jul 13 13:05 kernel/x86

drwxr-xr-x 1 root root 0 Jul 13 13:05kernel/x86/microcode

-rw-r–r– 1 root root 31744Jul 13 13:05kernel/x86/microcode/GenuineIntel.bin

================================================================

4. Edit /etc/default/grub, and add “ucode=scan” to Xenhypervisor command line:

GRUB_CMDLINE_XEN_DEFAULT=”vga=gfx-1024x768x16crashkernel=202M<4G ucode=scan”

5. Reboot.

6. Verify microcode is updated:

# grep -m1 microcode/proc/cpuinfo

microcode : 0x200004a

7. Verify new speculative mitigation features are availablethrough `xl dmesg`.

# xl dmesg | grep Speculative-A5

(XEN) Speculative mitigation facilities:

(XEN) Hardware features: IBRS/IBPB STIBP SSBD

(XEN) Compiled-insupport: INDIRECT_THUNK

(XEN) Xen settings: BTI-Thunk JMP,SPEC_CTRL: IBRS+ SSBD-, Other: IBPB

(XEN) Support for VMs: PV:MSR_SPEC_CTRL RSB, HVM: MSR_SPEC_CTRL RSB

(XEN) XPTI (64-bitPV only): Dom0 enabled, DomU enabled

Pre-SLES12SP1 Xen environments:

In SLES12SP1 and older(including SLES11), the Dom0 kernel (kernel-xen) is based onxenlinux. This environment can upgrade microcode from Dom0 atrun-time. However, the CPU is not re-sampled after such an update,and therefore guests cannot use new features exposed with an onlinemicrocode update. To avoid this problem, micocode updates should bedone using the following steps:

Installing a microcode update in SLES12SP1 and olderenvironments:

1. Install updated microcode package (microcode_ctrl).

2. Determine correct microcode file:

# grep -E ‘family|model|stepping’ -m 3/proc/cpuinfo

cpu family : 6

model : 62

model name :Intel(R) Xeon(R) CPU E7-4890 v2 @ 2.80GHz

stepping : 7

Intel microcode is named “[cpufamily]-[model]-[stepping]”, using hexadecimal values. In the aboveoutput, this would be “06-3e-07”.

AMD microcode is named”microcode_amd_fam[NN]h.bin”, where [NN] is the hexadecimalvalue of the CPU family. For example:

# grep -E ‘cpu family|model name’ -m 2/proc/cpuinfo

cpu family : 23

model name :AMD EPYC 7601 32-Core Processor

For the AMD CPU above, the applicablemicrocode would be /lib/firmware/amd-ucode/microcode_amd_fam17h.bin.

3. Copy the microcode file from /lib/firmware/intel-ucode to/boot as GenuineIntel.bin. (For AMD environments, use/lib/firmware/amd-ucode and AuthenticAMD.bin.)

# cp/lib/firmware/intel-ucode/06-3e-07 /boot/GenuineIntel.bin

NOTE – For EFI boot environments,the microcode should be copied to the EFI boot partition anddirectory used in booting. This is typically /boot/efi/efi/SuSE.

4. Edit /etc/default/grub, and make the following 2 changes:

– Add thefollowing module line in the Xen boot section, following the initrdmodule:

module /boot/GenuineIntel.bin

– Add “ucode=2” (where “2” is the “module” line number containing the GenuineIntel.bin string, starting from 0) to Xen hypervisor command line:

“kernel/boot/xen.gz vga=mode-0x317 ucode=2”

NOTEfor EFI boot environments, add the following line to the Xen efi bootconfiguration (/boot/efi/efi/SuSE/xen.cfg)entries.

“ucode=GenuineIntel.bin”

5. Reboot.

6. Verify new speculative mitigation features are availablethrough `xm dmesg`.

# xm dmesg | grep Speculative-A5

(XEN) Speculative mitigation facilities:

(XEN) Hardware features: IBRS/IBPB STIBP SSBD

(XEN) Xen settings:BTI-Thunk N/A, SPEC_CTRL: IBRS+ SSBD-, Other: IBPB

(XEN) Support for VMs: PV: MSR_SPEC_CTRL RSB, HVM: MSR_SPEC_CTRL RSB

(XEN) XPTI (64-bit PV only): Dom0 enabled, DomU enabled

NOTE: Multiple vendors may provide updated microcode. Ultimately,only the updates which matches the running CPU (using hex cupidcomparison) will be applied during the update process.

Related:

PVS 7.13: XenServer PVS-Accelerator Introduction and Requirements

Note: This feature is only available in XenServer 7.1 and PVS 7.13 or later.

XenServer PVS-Accelerator feature offers additional capabilities for customers using XenServer and Citrix Provisioning Services (PVS). With this feature, the read requests from a PVS target device can now be cached on each XenServer host, in a shared tiered read-cache.


How PVS-Accelerator Works

PVS-Accelerator employs a Proxy mechanism that resides in the Control Domain (dom0) of XenServer.

When this feature is enabled, PVS target device (VM) read requests (that is, boot from vDisk, launch an application, and so on) are cached directly on the XenServer host machine (that is, in physical memory and/or a storage repository).

When subsequent VMs (on the same XenServer host) boot from the same vDisk or launch the same application, the vDisk (contents) is streamed directly from cache instead of from the PVS Server. Removing the need to stream from the PVS Server reduces network utilization and processing on the server considerably, resulting in a substantial improvement in VM performance.

User-added image

When a VM with PVS-Accelerator enabled is started, PVS-Accelerator will create flow rules on Open vSwitch (OVS). In this way, all packets from this VM to PVS server will be redirected to PVS-Accelerator.

  1. PVS-Accelerator then checks if this packet is a read request of vDisk image:
    1. If it is not a read, PVS-Accelerator passes it straight back to the OVS;
    2. If it is a read, PVS-Accelerator processes it to see whether it has the data in the cache.
      1. If it’s a cache hit, PVS-Accelerator will return the cached data.
      2. If it’s not a cache hit, PVS-Accelerator passes it back to OVS and then the PVS server. The OVS flow rules work in both directions, so packets from the PVS server going to the VM are also redirected to PVS-Accelerator. If it is a read response coming from the server, PVS-Accelerator populate the cache with a certain PVS site, disk-id, block size and block contents.
  2. There are two Cache Storage modes:
    1. Memory only: explicitly uses Control Domain (Dom0) Memory
    2. On Storage Repository: implicitly uses available Dom0 memory and disk
  3. Cache manager (sub system of PVS-Accelerator) will monitor available space in Cache SR. If PVS Read cache SR is near full (90%) eviction algorithm will kick in and evict least recently used data.

XenServer PVS-Accelerator capabilities:

  • Caches reads from vDisks but not writes or reads from a write cache.
  • Supports vDisks with any non-persistent write cache type. It does not work for “Cache on Server, Persistent” and “Cache on device hard disk persisted” write cache type.
  • Caches vDisks with the access mode Standard Image. It does not work for vDisks with the access mode Private Image.
  • Caches devices that are marked as type Production. Devices marked as type Maintenance are not cached.

Prerequisites

  • PVS-Accelerator feature requires XenServer 7.1 and PVS 7.13
  • PVS-Accelerator is available for XenServer Enterprise Edition customers or those who have access to XenServer through their XenDesktop/XenApp entitlement
  • PVS-Accelerator feature leverages capabilities of Open vSwitch (OVS) and is therefore not available on hosts that use Linux Bridge as the network backend.
  • PVS-Accelerator Cache works only on the first virtual network interface (VIF) of a cached VM. Therefore, the first VIF should be used for connecting the PVS Server for the PVS-Accelerator caching to work.

Additional Resources

Related:

7023314: Newest kernel-xen updates on dom0 makes guests fail to start

This document (7023314) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11

SUSE Linux Enterprise Server 12

Situation

Since the new updates for xen the domU’s are not starting and crashing:
(XEN) d2 L1TF-vulnerable L1e 000000003bd63160 - Shadowing

(XEN) d2 Failed to enable PG_SH_forced: -12
(XEN) domain_crash called from common.c:3964
(XEN) Domain 2 reported crashed by domain 32767 on cpu#0:

Resolution

As a workaround disable autoballooning on dom0, which is enabled by default.

Add autoballoon=0 to /etc/xen/x1.conf

https://www.suse.com/documentation/sles-12/book_virt/data/sec_xen_vhost_memory.html

As soon as a permanent fix is available this Bulletin will be updated

Cause

This is caused by the implementation of the L1TF mitigation fixes.

Disclaimer

This Support Knowledgebase provides a valuable tool for NetIQ/Novell/SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented “AS IS” WITHOUT WARRANTY OF ANY KIND.

Related:

How to Factory Reset a CloudBridge 400, 800, 2000, 3000, 4000, or 5000 Appliance by Using XenServer

To reset the CloudBridge 400, 800, 2000, 3000, 4000 and 5000 appliances to factory default state by using XenServer, complete the following procedure:

  1. Connect a serial cable to the serial port for monitoring the rebuild process.

  2. Open a Secure Shell (SSH) session to the XenServer IP address and log on with the default credentials (root / nsroot).

  3. Run the following commands to stop the IPMI timer before starting the factory reset process:

    service ftwd stop

    ipmitool mc watchdog off

    User-added image

    Note: You might see a different output for the ipmitool command when using CloudBridge 4000 or 5000 appliance. This can be safely ignored. However, if the output is different for CloudBridge 2000 or 3000 appliance, then troubleshoot the issue further.

  4. Run the fdisk command on the sda partition:

    fdisk /dev/sda

    User-added image

  5. Mark the first partition active, second partition not active, and change the partition type to 0xc:

    a<ENTER> 1 <ENTER>

    a <ENTER> 2 <ENTER>

    t <ENTER> 1 <ENTER> c <ENTER>

    User-added image

  6. Verify the changes:

    p <ENTER>

    User-added image

  7. Write the changes:

    w <ENTER>

    User-added image

  8. Press Ctrl+C on the keyboard to exit fdisk.

  9. Restart the system from Dom0:

    sync;sync;reboot

    User-added image

The rebuild process takes 20 to 30 minutes to complete. The system restarts into the XenServer installation process and completes multiple restarts. If the serial console is being monitored and if the system does not respond during the initial stage, then power cycle the appliance. Else, do not power off during the factory reset.

After the process is complete you will have CloudBridge appliance with factory default settings. The Management Service virtual machine should now be accessible by using the default IP 192.168.100.1 for initial configuration.

If your appliance is a CB4000 or CB5000, please refer to article CTX200902 on how to re-provision it to 7.2.2, and from here we can upgrade to 7.4.6, 9.0.1 and 9.x

Related:

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7022995: Accessing All Open “Reflection Workspace” Objects in VBA Macro Code

Option Explicit

'Returns a Collection object that contains all open Reflection Frame objects

Function GetAllFrames() As Collection

Dim Frames As New Collection

Dim rApp As Attachmate_Reflection_Objects_Framework.ApplicationObject

On Error Resume Next

'By default, all Reflection Application objects will have the

'"AutomationServerName" of "Reflection Workspace".

'So, this method of discovering all currently-running Application

'objects works as long as you have not used another program

'that changes the default value on these to something else.

Do

Set rApp = GetObject("Reflection Workspace")

If Err = 0 Then

Frames.Add rApp.GetObject("Frame")

rApp.AutomationServerName = "already got this one"

Else

Err.Clear

Exit Do

End If

Loop

'Reset back to the original AutomationServerName...

Do

Set rApp = GetObject("already got this one")

If Err = 0 Then

rApp.AutomationServerName = "Reflection Workspace"

Else

Err.Clear

Exit Do

End If

Loop

Set GetAllFrames = Frames

End Function

'Returns a Collection object that contains all open Views

'in all Open Reflection Frame objects.

Function GetAllViews() As Collection

Dim Frames As Collection

Dim Views As New Collection

Dim i As Long

Dim f As Frame

Set Frames = GetAllFrames()

For Each f In Frames

If f.ViewCount <> 0 Then

For i = 1 To f.ViewCount

Views.Add f.View(i)

Next

End If

Next

Set GetAllViews = Views

End Function

'test...

Sub ReportAllViewTitles()

Dim Views As Collection

Dim v As View

Set Views = GetAllViews()

For Each v In Views

Debug.Print v.titleText

Next

End Sub

Related:

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How to license Citrix Hypervisor versions 5.6 and higher

Free Citrix Hypervisor 5.6-6.1

Free Citrix Hypervisor 6.2

Installation of license for Citrix Hypervisor 6.2

Retail Citrix Hypervisor


Free Citrix Hypervisor 5.6 – 6.1 Activation using License Manager in XenCenterWhen a server is installed with the free Citrix Hypervisor, you have up to 30 days of use until you must activate the server. Follow the below procedure to activate Citrix Hypervisor using License Manager in XenCenter:

  1. Launch XenCenter.
  2. Click Tools and select License Manager.
  3. The License Manager pop up box is displayed with a list of products and servers. Select the License server to activate your free Citrix Hypervisor 5.6.
  4. From the dropdown box available at the bottom of the page, select Request Activation Key.
  5. On the Citrix Hypervisor activation web page, Enter your valid contact information
    • The licensing file will be sent to the entered Email ID.
  6. Select the Download Agreement check box and click Submit.
Please Note:
  1. A confirmation message will be displayed, informing that your license file will be mailed to your Email ID within 5 minutes.
  2. Open your Email and it will have a license file sent from Xenserver.activations@citrix.com. Save the license file in a location where it can be accessible from the XenCenter console.
  3. In the XenCenter, Click License Manager and select Apply Activation Key from the dropdown box available at the bottom of the page.
  4. Browse for the downloaded license file and select the license file and click Open.
  5. A pop up box is displayed that shows the expiry date of the hypervisor. The Citrix Hypervisor will be ready to use for a 30 day trial period.

Free Citrix Hypervisor 6.2

With the release of Citrix Hypervisor 6.2, Citrix has unlocked all features in the free version and removed the need for a license. To obtain the free version, follow the below steps:

  1. Go to www.xenserver.org
  2. Select the Software link at the top of the page
  3. The next page provides all downloads applicable to Citrix Hypervisor, Select the media desired
  4. Save the media on the desktop and proceed to install.


Installation of license for Citrix Hypervisor 6.2 Free version

There is no license to install therefore there will be no need for a license. To view the system and verify there is no license, follow the below steps:

  1. Open XenCenter
  2. Navigate to the Tools menu and click License Manager
  3. This will show the license manager server option as Unsupported

Retail Citrix Hypervisor editions

There are two types of Citrix Hypervisor editions available which uses retail licensing. The types of hypervisor editions are Citrix Hypervisor Standard Edition, and Citrix Hypervisor Premium Edition. All Citrix Hypervisor editions licenses have to be added to a separate Citrix Licensing Server. The license files are maintained and controlled using Citrix License Administrative (LAC) console

Each host in a resource pool must be individually licensed. (For example, if you are supporting four hypervisor hosts in a resource pool, you must configure the license type to use on each of the four hosts separately.) As a result, license settings are configured on each host in the pool. However, in XenCenter, you can select multiple hosts at once in the License Manager and apply the same settings to them.


Tasks required to License Citrix Hypervisor retail editions

Follow the below tasks to license Citrix Hypervisor retail editions:

  1. Create a Citrix license server. Citrix Hypervisor release requires the Citrix License Server, version 11.6.1 or higher http://support.citrix.com/proddocs/topic/licensing-1110/lic-install.html

  2. Download and add the Citrix Hypervisor license file to the Citrix License Server CTX130884-How to Download the Citrix Hypervisor License File from My Account Portal / CTX126338-How to Add Allocated License Files to the License Administration Console.

  3. Configure each Citrix Hypervisor host to use the Citrix License Server that is hosting the license you allocated for it CTX130884-How to Download the Citrix Hypervisor License File from My Account Portal / CTX126338-How to Add Allocated License Files to the License Administration Console.

Retail Licensing for Citrix Hypervisor activation using License Manager in XenCenter

Follow the below procedure to activate Citrix Hypervisor using License Manager in XenCenter:

  1. Open XenCenter. Click Tools and select License Manager.
  2. The License Manager pop up box is displayed. Select required hosts (you can select more than one host file) and Click Assign License.
  3. The Apply License dialog box is displayed. Under the License Edition section, select the type of your hypervisor (For example, if you have Citrix Hypervisor Premium Edition, click on the radio button against it).
  4. Under License Server section, enter the name of the server in Name field (by default, it will have Local host text, Delete it and enter the name of the server) and port number of the server in Port Number field.
Note: If you have changed the port on the Citrix License Server, specify the changed port number in the Port Number field. If you have not changed the port, leave the default value 27000 as is. 27000 is the default port number used by Citrix products.
  1. Click OK.
  2. The licensing file will be associated with Citrix Hypervisor and the server is ready to use.

Related: