vSphere Distributed Resource Scheduler (DRS) Part I I

If VM has high space vmdk > it’s NOT recommended to configure [SDRDS] > Since it will slow our performance

DRS and SDRS is working automatically >  So we need to control DRS using : [DRS rules ]

• Sometime we need that 2 VMs should NOT be in same host : for example Exchange CAS 1 and CAS 2 [if that host down then ALL CAS server will be down and exchange environment lost  ] à we need to configure
• Sometime we need 2 VMS to be in same Host : for example SharePoint front end and its SQL database [for best performance and faster IOps transaction à we need to configure

Automation level : recommended to be fully automated

Threshold: from conservative [which accept ONLY priority 1] à to aggressive [which accept DRS for priority 1,2,3,4,5] à please note VMWARE highly recommend to apply aggressive

Predictive : if enable à it will rely on history of VMWARE VROPS [to be discussed later ]  *  by default DRS work after Host resource Overload happened but with this feature DRS will happen before resource overload  

VM distribution : if enabled à make all VMs in resources with same number [NOT based on load but based on VM quantity]

We can configure DRS based active RAM[Assigned] or consumed RAM

Same thing also for CPU [consumed CPU rather Assigned ]

Distributed Power management DPM : only used by ISP when there huge environment : which used to save power for some VMs

How to create [affinity rule ]

• Host and cluster à select Cluster configuré à configuration à configure VM/host rule à create rule à select either :
• [keep VM together ]
• or [separate VM]
• keep VM on specific HOST
• when create Rule à we have to differentiate between
• should: meaning apply as much as possible but will move VM if Host  going down
• must : which mean rule will be applied and there is NO override à so if host going down à VM will NOT move will be down also

Exclude VMD from DRS

Host and cluster à select Cluster àconfigure à configuration à configure VM override : will exclude VM from apply DRS à and apply specific settings for that VM

Please note : Since we are using LAB and there is NO resources overload à DRS will NOT provide us with Added value à but it’s very important to configure it in production environment

DPM Distributed Power Management

• DPM is a DRS “extension” that helps to save power (so we can be “green”).
• It recommends powering off or on ESX hosts when either CPU or memory resource utilization decreases or increases.
• VMware DPM also takes into consideration VMware HA settings or user-specifies constraints
• It means that e.g. if our HA tolerates one host failure, à  DPM will leave at least two ESXi host powered on.
• How does DPM contact with ESXi host?
• It uses wake-on-LAN (WoL) packets or these out-of-band methods: Intelligent Platform Management Interface (IPMI) or HP Integrated Lights-Out (iLO) technology.  
• When DPM powers off ESXi host, that host is marked as Standby (standby mode).