Did I Just… ?
Have you ever had one of those moments where you are working remotely on a system that could impact overall network connectivity, then midway through whatever it is that you are doing, your remote session drops out?
Yeah... I damn near just had a heart attack. I spent most of tonight patching XenApp servers in preparation for a large Edgesight rollout. During the early stages, while I was patching the data collectors, my remote session dropped and wouldn't reconnect. My first thought was 'dear god I broke the farm', but thankfully it was just my router being a piece of crap and rebooting for no reason.
Another odd discovery tonight was that our two load balanced web interfaces are configured differently. Not sure why that would have been done - it just doesn't make much sense - but it did cause me some confusion while testing data collector elections post patching. If the netscaler balanced my initial connection to the second WI and the first preferred data collector was offline, it wouldn't find the second one because it didn't have it listed, giving me no Xenapp applications. The first WI doesn't have this problem as it has both data collectors in its list.
I might look at bootstrapping the WIs to use a config file from one of the file clusters..
XenDesktop 5 Study – Part 1
Identifying Pre-installation Requirements
Determine the requirements for the SQL (controller) database based on a description of an environment.
Supported Databases:
- SQL Server 2008 R2
- SQL Server 2008 R2 Express (Default for Quick Deploy)
- SQL Server 2008 SP1 or later
HA Approaches
- SQL Mirroring
- Hypervisor HA
- SQL Clustering
Determine desktop storage requirements based on a given environment
5000 Unmanaged Desktops will use approximately 40MB of DB space.
5000 Provisioned (MCS) Desktops will use approximately 59MB of DB space
5000 Desktops can generate approximately 8GB of transaction logs in 24 hours. Recommend using simple backups or frequent full backups for DB maintenance.
Based on a described environment or requirements, determine the optimal write cache location
Device Hard Drive - Stores the write cache on the target device's hard drive. Removes resources load from the Provisioning Server.
Device Hard Drive Persistent - Same as Device Hard Drive, but persists between reboots.
Device RAM - Puts the write cache in the target device RAM, very fast, but may be limited space.
Server Disk - Writes the cache back to the Provisioning Server, puts heavy I/O and network load on the server (this is the default setting for vDisks).
Server Disk Persistent - As above, but persists between reboots. All persistent files are invalidated if the master vDisk is changed.
Based on a description of an environment, determine the number of controllers and/or Provisioning services servers required for a XenDesktop environment
Rules for XenDesktop Controllers:
- N+1 Always ensure there is extra (controller) capacity in event of failure.
- 125-180 Desktop Registration per dedicated CPU Core
- 100-120 Logins per minute per dedicated CPU Core
2 Controller VMs with: 2x vCPU, 4GB of RAM providing Provsioning Services powered desktops can handle 2500 Desktops with an average launch and logon operation of 2.5 seconds.
Assumes resources, especially SQL, are not overcommitted.
Provisioning Services (5.6 SP1)
- Minimum spec is: 2GHz CPU, 2GB of RAM, 100Mbit NIC, Server 2003 SP2.
- Recommended: 3.5GHz DualCore/HT or higher, 4GB or higher, Dual 1GB NIC
- Virtual Provisioning Servers are supported
- Virtual Provisioning Server with 4vCPU, 40GB of RAM and a 10GB NIC can support 1500+ target devices per server with write cache on target device.