Lab Manager Maintenance July, 2008 VMware Confidential Lab Manager 3 Training Series Module 9

Module Agenda Maintaining Linked Clone Chains  Background; How they work  Performance (generally not an issue)  Maintenance Datastore Maintenance  Gold Master Trees  Cleanup Strategies  Setting User Expectations  Naming Strategies Maintaining Guests  Patching  License Management Questions

COW Disks Lab Manager creates copies of disks as COW disks unless explicitly directed otherwise  Saves time and storage resources  Performance is generally not an issue  Maintenance requirements should be considered “Copy On Write” (COW) Disks  Initial COW disk is 16MB  A write copies block to sparse disk, then writes data  Reads made through COW data structure mapping blocks to files in VM overhead memory  Only leaf node is R/W. All internal nodes are read-only.  Lab Manager keeps all COW disks in a tree on the same datastore

Performance of COW Disks COW disks can perform better or worse than monolithic disk depending on the usage profile. Performance is not strongly affected by chain length. Read performance hit  Startup delayed as COW data structure read into overhead memory  Cache miss caused by diverse reads will result in multiple physical reads per virtual read Write performance hits  Copy process causes extra physical read and write when writing to new blocks  Extending sparse file causes SCSI lock on VMFS Read Performance gain (can be big)  Storage Arrays cache small read-only COW disks in memory so reads happen from RAM instead of spindle

How Lab Manager uses COW Disk: Cloning Clone Library Config 4 timesClone Workspace Config 4 times Chain length grows much faster when cloning from Workspace because parent can still change, requiring a “double-headed” clone. Take clones from the Library to control chain length and reduce maintenance.

How Lab Manager uses COW Disks: Snapshots Start Chain length grows for each snapshot. When reverting chain length does not decrease. Use snapshots sparingly and capture to Library instead to reduce maintenance. 1 0 Snapshot Revert Snapshot 3 To be garbage collected

Standard Maintenance COW disk chain length limit is 30  Consolidate disk before it hits limit onto same or different datastore. Consider deleting original tree of disks when appropriate  Don’t worry about consolidating early– it just creates more work for little benefit  Understand and use Gold Masters for maintainability  Lab Manager keeps chains of disks on the same datastore. Use copy and delete commands to move nodes between datastores if necessary … Gold Master “Tree” When users go back to the Gold Master to clone, chain length is minimized.

Controlling Disk Chain Length Do this to minimize maintenance, not for performance Instruct users on preferred usage patterns  Clone from the Library, not the Workspace  Don’t use snapshots excessively  Go back to original Library entry or Gold Master where possible Set a policy for cleanup of disk files  Use Storage Leases  Use Gold Masters and control who has rights to set them  Have users identify which clones can be deleted, when..  Naming strategies  Datastore strategies  Combination of both

Storage Leases and Gold Masters Storage Leases are very powerful  Users can extend leases  Automatically prunes trees in a socially-acceptable way Gold Masters control tree depth  By having users clone gold masters, tree depth is controlled. Everybody clones from minimum length version; only gold masters need to be consolidated … Gold Master “Tree”

Datastore-based Cleanup Strategy Organize data by datastore based on retention policies. For example:  Gold Master datastore collects gold versions of the supported platforms  User datastore is organized by software version, and deleted when version is shipped or EOL  Organizations can also be used in conjunction with this strategy to manage user access to the datastore User Datastore contains everything for a particular version of the product. Most items deleted after version is shipped; rest deleted at EOL User Datastore Backup Gold Master Base Disk Gold Master Datastore Gold Master Consolidate or add to configuration

Naming-Based Cleanup Strategy  Have users name configurations so that things that can be deleted can be identified  Delete after hotfix is released  Delete after version is released  Delete after version is EOL  Set up policies for naming. Recommendations are to keep names:  Short  Uniquely identifiable  Easily distinguishable  Sortable and Filterable in LM

Maintaining Guests Patching guests requires planning  Patches create another independent VM; they do not “update” existing checkouts.  Use Gold Masters to control chain length and organize maintenance when frequent patching is required  Consider automation if patching needs are predictable License Management  Use developer licenses when possible  Most Lab Manager VMs copies are stored in the library and do not require additional licenses  Template naming and filtering can be used to understand number of core applications deployed at any given time

Questions

Lab Manager 3 Training  Module 1: Lab Manager Overview  Module 2: Lab Manager 3 New Features  Module 3: Lab Manager Under the Covers  Module 4: Architecting a Lab Manager Installation  Module 5: Lab Manager Use Cases  Module 6: Installing Lab Manager  Module 7: Administering Templates, Media, Users, and Resources  Module 8: Administering Lab Manager Settings  Module 9: Lab Manager Maintenance  Module 10: Troubleshooting Lab Manager