Hotfix XS71ECU2020 – For XenServer 7.1 Cumulative Update 2

Who Should Install This Hotfix?

This is a hotfix for customers running XenServer 7.1 Cumulative Update 2.

Note: This hotfix is available only to customers on the Customer Success Services program.

Information About this Hotfix

Component Details
Prerequisite None
Post-update tasks None
Content live patchable** No
Baselines for Live Patch N/A
Revision History

Published on Nov 20, 2019

** Available to Enterprise Customers.

Issues Resolved In This Hotfix

This hotfix resolves the following issues:

  • Sometimes, the storage garbage collection process might run continuously, taking snapshots, coalescing them, deleting the snapshots, and then repeating on an almost permanent basis. This introduces high IOPS load for little benefit.
  • When read caching is enabled it is significantly slower to read from the parent snapshot than from the leaf. This is now fixed for sequential reads.
  • On HA-enabled pools, when a task is initiated after a XenServer host has failed, VMs on the host can be blocked from restarting for many hours. This issue occurs when an in-progress coalesce process is not explicitly aborted after the failure.
  • All VMs on a XenServer host can experience slower read/write performance, during a VM disk copy, and up to 512 seconds after the copy finishes. The degradation of performance is caused by cache memory pressure in dom0 causing all tapdisks to incorrectly enter low memory mode.

    Important: This hotfix disables low memory mode. Therefore, VMs might require more memory to be available in dom0. Before applying this hotfix, you can check whether any of your VMs are running in low memory mode by adding the “Tapdisks in Low Memory Mode” graph to the Performance tab in XenCenter. The number of VMs in low memory mode is shown on this graph. We recommended that you increase dom0 memory to make an additional ~1.4MB per VM available in dom0.

This hotfix also includes the following previously released hotfixes:

Installing the Hotfix

Customers should use either XenCenter or the XenServer Command Line Interface (CLI) to apply this hotfix. When the installation is complete, see the Post-update tasks in the table Information About this Hotfix for information about any post-update tasks you should perform for the update to take effect. As with any software update, back up your data before applying this update. Citrix recommends updating all hosts within a pool sequentially. Upgrading of hosts should be scheduled to minimize the amount of time the pool runs in a “mixed state” where some hosts are upgraded and some are not. Running a mixed pool of updated and non-updated hosts for general operation is not supported.

Note: The attachment to this article is a zip file. It contains the hotfix update package only. Click the following link to download the source code for any modified open source components XS71ECU2020-sources.iso. The source code is not necessary for hotfix installation: it is provided to fulfill licensing obligations.

Installing the Hotfix by using XenCenter

Choose an Installation Mechanism

There are three mechanisms to install a hotfix:

  1. Automated Updates
  2. Download update from Citrix
  3. Select update or Supplemental pack from disk

The Automated Updates feature is available for XenServer Enterprise Edition customers, or to those who have access to XenServer through their XenApp/XenDesktop entitlement. For information about installing a hotfix using the Automated Updates feature, see the Applying Automated Updates in the XenServer documentation.

For information about installing a hotfix using the Download update from Citrix option, see Applying an Update to a Pool in the XenServer documentation.

The following section contains instructions on option (3) installing a hotfix that you have downloaded to disk:

  1. Download the hotfix to a known location on a computer that has XenCenter installed.
  2. Unzip the hotfix zip file and extract the .iso file
  3. In XenCenter, on the Tools menu, select Install Update. This displays the Install Update wizard.
  4. Read the information displayed on the Before You Start page and click Next to start the wizard.
  5. Click Browse to locate the iso file, select XS71ECU2020.iso and then click Open.
  6. Click Next.
  7. Select the pool or hosts you wish to apply the hotfix to, and then click Next.
  8. The Install Update wizard performs a number of update prechecks, including the space available on the hosts, to ensure that the pool is in a valid configuration state. The wizard also checks whether the hosts need to be rebooted after the update is applied and displays the result.
  9. Follow the on-screen recommendations to resolve any update prechecks that have failed. If you want XenCenter to automatically resolve all failed prechecks, click Resolve All. When the prechecks have been resolved, click Next.

  10. Choose the Update Mode. Review the information displayed on the screen and select an appropriate mode.
  11. Note: If you click Cancel at this stage, the Install Update wizard reverts the changes and removes the update file from the host.

  12. Click Install update to proceed with the installation. The Install Update wizard shows the progress of the update, displaying the major operations that XenCenter performs while updating each host in the pool.
  13. When the update is applied, click Finish to close the wizard.
  14. If you chose to carry out the post-update tasks, do so now.

Installing the Hotfix by using the xe Command Line Interface

  1. Download the hotfix file to a known location.
  2. Extract the .iso file from the zip.
  3. Upload the .iso file to the Pool Master by entering the following commands:

    (Where -s is the Pool Master’s IP address or DNS name.)

    xe -s <server> -u <username> -pw <password> update-upload file-name=<filename>XS71ECU2020.iso

    XenServer assigns the update file a UUID which this command prints. Note the UUID.


  4. Apply the update to all hosts in the pool, specifying the UUID of the update:

    xe update-pool-apply uuid=52a16dea-740a-4a39-8a5e-8b71d617f13d

    Alternatively, if you need to update and restart hosts in a rolling manner, you can apply the update file to an individual host by running the following:

    xe update-apply host=<host> uuid=52a16dea-740a-4a39-8a5e-8b71d617f13d

  5. Verify that the update was applied by using the update-list command.

    xe update-list -s <server> -u root -pw <password> name-label=XS71ECU2020

    If the update is successful, the hosts field contains the UUIDs of the hosts to which this patch was successfully applied. This should be a complete list of all hosts in the pool.

  6. Use the update-pool-clean command to remove the update files from all hosts in the pool. This command frees up space on shared storage and does not uninstall the update.

    xe update-pool-clean uuid=52a16dea-740a-4a39-8a5e-8b71d617f13d


Hotfix File

Component Details
Hotfix Filename XS71ECU2020.iso
Hotfix File sha256 f9d5b0aad2cd089a4ae7340852704b9008cafca30f0c4a5f45efe40e2d06c83f
Hotfix Source Filename XS71ECU2020-sources.iso
Hotfix Source File sha256 a772d8816e6bb2cb14fba178c36a5df8fef4bb8fbd8a0b914d937ebf16bb042c
Hotfix Zip Filename
Hotfix Zip File sha256 5fbcd65dd92c6a93164e7b47418b382ce23d9f92483284bc84aa8886645b9cfe
Size of the Zip file 1.24 MB

Files Updated


More Information

For more information, see XenServer Documentation.

If you experience any difficulties, contact Citrix Technical Support.


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